Gas compressor and system and method for gas compressing

Abstract

Methods and systems are provided to adaptively control a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes. During a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston is monitored. Reversal of the driving force after the first stroke is controlled based on the speed, load pressure, and temperature.

1 . A method of adaptively controlling a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes, the method comprising:
 monitoring, during a first stroke of the piston, a speed of the piston, a temperature of the driving fluid, and a load pressure applied to the piston; and   controlling reversal of the driving force after the first stroke based on the speed, load pressure, and temperature.   
     
     
         2 . The method of  claim 1 , wherein controlling reversal of the driving force comprises determining a lag time before reversing the direction of the driving force, and delaying reversal of the driving force by the lag time. 
     
     
         3 . The method of  claim 2 , further comprising:
 monitoring whether the piston has or has not reached a predefined end position during a previous stroke; and   in response to the piston not reaching the predefined end position during the previous stroke, increasing the lag time by a pre-selected increment.   
     
     
         4 . The method of  claim 3 , wherein the pre-selected increment is 1 millisecond. 
     
     
         5 . The method of any one of  claims 2 to 4 , further comprising:
 monitoring an end of stroke event; and   in response to occurrence of the end of stroke event, decreasing the lag time by a sufficient amount to avoid recurrence of the end of stroke event in subsequent strokes.   
     
     
         6 . The method of any one of  claims 2 to 5 , wherein the lag time is decreased as the temperature decreases below a temperature threshold. 
     
     
         7 . The method of any one of  claims 2 to 6 , wherein the lag time is increased as the load pressure increases. 
     
     
         8 . The method of  claim 7 , wherein the lag time is increased by an amount linearly proportional to the load pressure. 
     
     
         9 . The method of any one of  claims 1 to 8 , wherein the gas compressor is a double-acting gas compressor. 
     
     
         10 . The method of  claim 9 , wherein the gas compressor comprises a gas cylinder and first and second hydraulic cylinders; wherein the gas cylinder comprises a gas chamber for receiving a gas to be compressed and having a first end and a second end, and each of the first and second hydraulic cylinders comprises a driving fluid chamber for receiving the driving fluid; and wherein the piston comprises a gas piston reciprocally moveable within the gas chamber for compressing the gas received in the gas chamber towards the first or second end; and a hydraulic piston moveably disposed in each driving fluid chamber and coupled to the gas piston such that reciprocal movement of the hydraulic piston causes corresponding reciprocal movement of the gas piston. 
     
     
         11 . The method of any one of  claims 1 to 10 , wherein the speed of the piston is monitored using first and second proximity sensors positioned and configured to respectively generate a first signal indicative of a first time (T 1 ) when a first part of the piston is in a proximity of the first proximity sensor, and a second signal indicative of a second time (T 2 ) when a second part of the piston is in a proximity of the second proximity sensor, whereby the speed of the piston is calculable based on T 1 , T 2  and a distance between the first and second proximity sensors, and wherein the load pressure is measured at T 1  or T 2 . 
     
     
         12 . The method of any one of  claims 1 to 11 , wherein the temperature of the driving fluid is monitored using a temperature sensor mounted in the gas compressor or in the hydraulic fluid supply. 
     
     
         13 . The method of any one of  claims 1 to 12 , wherein the hydraulic fluid supply comprises a hydraulic pump having first and second ports for supplying the driving fluid and applying the driving force, and wherein the load pressure is monitored by monitoring a fluid pressure differential between the first and second ports. 
     
     
         14 . A control system for adaptively controlling a hydraulic fluid supply to supply a driving fluid for applying a driving force on a piston in a gas compressor, the driving force being cyclically reversed between a first direction and a second direction to cause the piston to reciprocate in strokes, the system comprising:
 first and second proximity sensors positioned and configured to respectively generate a first signal indicative of a first time (T 1 ) when a first part of the piston is in proximity of the first proximity sensor, and a second signal indicative of a second time (T 2 ) when a second part of the piston is in a proximity of the second proximity sensor, whereby the speed of the piston is calculable based on T 1 , T 2  and a distance between the first and second proximity sensors;   one or more pressure sensors positioned and configured to generate a signal indicative of a load pressure applied on the piston;   a temperature sensor positioned and configured to generate a signal indicative of a temperature of the driving fluid; and   a controller configured to receive signals from said sensors and for controlling the hydraulic fluid supply to control reversal of the driving force based on the speed of the piston, the temperature of the driving fluid, and the load pressure applied to the piston during the first stroke.   
     
     
         15 . The system of  claim 14 , wherein the controller is configured to determine a lag time before reversing the direction of the driving force, and to delay reversal of the driving force by the lag time after T 2 . 
     
     
         16 . The system of  claim 15 , further comprising an indicator positioned and configured for generating an end of stroke signal when the piston has reached a predefined end position in the first stroke, wherein the controller is configured to, in response to not receiving the end of stroke signal during the first stroke, increase the lag time by a pre-selected increment. 
     
     
         17 . The system of  claim 16 , wherein the pre-selected increment is 1 millisecond. 
     
     
         18 . The system of  claim 16 or claim 17 , wherein the indicator for generating the end of stroke signal is a third proximity sensor. 
     
     
         19 . The system of any one of  claims 15 to 18 , wherein the controller is further configured to determine if an end of stroke event has occurred based on a change in the load pressure; and in response to occurrence of the end of stroke event, to decrease the lag time by a sufficient amount to avoid recurrence of the end of stroke event in subsequent strokes. 
     
     
         20 . The system of any one of  claims 15 to 19 , wherein the controller is configured to decrease the lag time when the temperature decreases below a temperature threshold. 
     
     
         21 . The system of any one of  claims 15 to 20 , wherein the controller is configured to increase the lag time when the load pressure increases. 
     
     
         22 . The system of  claim 21 , wherein the lag time is increased by an amount linearly proportional to the load pressure. 
     
     
         23 . A gas compressing system comprising:
 a gas compressor comprising
 a gas chamber for receiving a gas, having a first end and a second end; and 
   a gas piston reciprocally moveable in the gas chamber for compressing the gas towards the first or second end;   a hydraulic fluid supply for supplying a driving fluid to apply a driving force to the gas piston, the driving force cyclically reversible between a first direction and a second direction to cause the gas piston to reciprocate in strokes; and   a control system according to any one of  claims 14 to 21  for controlling the hydraulic fluid supply and the driving force applied to the gas piston.   
     
     
         24 . The gas compressing system of  claim 23 , wherein the gas compressor is a double-acting gas compressor. 
     
     
         25 . The gas compressing system of  claim 24 , wherein the gas compressor comprises first and second hydraulic cylinders, each comprising a driving fluid chamber for receiving the driving fluid and a hydraulic piston moveably disposed therein and coupled to the gas piston, such that reciprocal movement of the hydraulic piston causes corresponding reciprocal movement of the gas piston. 
     
     
         26 . The gas compressing system of any one of  claims 23 to 25 , wherein the hydraulic fluid supply comprises a hydraulic pump having first and second ports for supplying the driving fluid and applying the driving force. 
     
     
         27 . A gas compressor system comprising:
 a controller;   a gas compressor comprising:   a first driving fluid cylinder having a first driving fluid chamber adapted for containing a first driving fluid therein, and a first driving fluid piston movable within said first driving fluid chamber;   a gas compression cylinder having a gas compression chamber comprising a first end and a second end, the gas compression chamber adapted for holding a gas therein and a gas piston reciprocally movable within said gas compression chamber between said first and said second end for compressing a gas;   a second driving fluid cylinder having a second driving fluid chamber adapted for containing a second driving fluid therein, and a second driving fluid piston movable within said second driving fluid chamber;   said first and second driving fluid cylinders located at each end of the gas compression cylinder and each of said first and second driving fluid pistons connected to said gas piston for axially driving said gas piston between said first and said second end;   a first and a second proximity sensor respectively coupled to said first and second driving fluid cylinders, said first and second proximity sensors respectively operable to indicate a first and second time when a pre-defined portion of said first and said second driving fluid pistons is proximal to a respective one of said sensors and send said first and said second time to said controller in response thereto, said controller for determining a speed of movement of said gas piston within said gas compression chamber between said first and second end based on said first and second time;   a temperature sensor coupled to one of said driving fluid cylinders and operable to detect a temperature of a respective one of said driving fluids and provide a temperature signal indicative of said temperature to said controller;   a pressure sensor coupled to said driving fluid cylinders and operable to detect a pressure difference between said first and second driving fluids and provide a pressure signal indicative of said pressure difference to said controller; and   said controller in communication with said temperature sensor, said pressure sensor and said first and second proximity sensors, said controller configured to control the flow of driving fluid into and out of each of said driving fluid chambers for causing a subsequent movement of said gas piston in an opposite direction between said second end and said first end in a second other stroke in response to said pressure signal, said temperature signal and said speed.   
     
     
         28 . The gas compressor system of  claim 27 , wherein said controller determines a time delay in response to each said pressure signal, said temperature signal and said speed, said controller configured to wait a pre-determined amount of time equivalent to the time delay prior to initiating movement of said gas piston between subsequent strokes. 
     
     
         29 . The gas compressor system of  claim 28 , further comprising an end of stroke indicator coupled to said gas compressor, each end of stroke indicator for detecting when a position of said first and second driving fluid pistons is proximate a pre-determined location indicative of an end point of a drive stroke, said detecting of position being transmitted to said controller to adjust the time delay in response thereto. 
     
     
         30 . The gas compressor system of  claim 27 , wherein said controller is configured to calculate the speed based on a time difference between said first and second time and a fixed distance between said first and the second proximity sensor. 
     
     
         31 . A gas compressor system comprising:
 a driving fluid cylinder having a driving fluid chamber adapted for containing a driving fluid therein, and a driving fluid piston movable within said driving fluid chamber;   a gas compression cylinder having a gas compression chamber adapted for holding a gas therein and a gas piston movable within said gas compression chamber;   a buffer chamber located between said driving fluid chamber and said gas compression chamber;   
       said buffer chamber adapted to inhibit movement of at least one non-driving fluid component, when gas is located within said gas compression chamber, from said gas compression chamber into said driving fluid chamber. 
     
     
         32 . A gas compressor systems as claimed in  claim 31  wherein said buffer chamber is adapted such that during operation when said when gas is compressed in said gas compression chamber, said buffer chamber is operable to inhibit movement of at least one non-driving fluid component, when gas is located within said gas compression chamber, from said gas compression chamber into said driving fluid chamber. 
     
     
         33 . A gas compressor system as claimed in  claim 31 or 32  further comprising a piston rod that is fixedly connected to said driving fluid piston and said gas piston, such that in operation when said driving fluid flows into said driving fluid chamber said driving fluid piston drives said driving fluid piston such that said driving piston and said gas piston move together within said respective driving fluid chamber and said gas compression chamber. 
     
     
         34 . A gas compressor as claimed in  claim 33  wherein a volume of said driving fluid chamber and a volume of said buffer chamber overlap within said driving fluid cylinder. 
     
     
         35 . A gas compressor as claimed in  claim 33 or 34  wherein said piston rod extends from said driving fluid piston through said buffer chamber into said gas compression chamber to said gas piston. 
     
     
         36 . A gas compressor as claimed in any one of  claims 31 to 35  wherein during operation, said buffer chamber varies in length dependent upon the position of said driving fluid piston in said driving fluid cylinder. 
     
     
         37 . A gas compressor as claimed in  claim 35  wherein during operation, said buffer chamber varies in length dependent upon the position of said driving fluid piston in said driving fluid cylinder and the minimum length of said buffer chamber is greater than the stroke length of said gas piston, said piston rod and said hydraulic fluid piston. 
     
     
         38 . A gas compressor as claimed in  claim 35  wherein said buffer chamber is configured such that in operation, no portion of said piston rod that is received within said gas compression chamber will be received in a portion of said hydraulic cylinder that receives hydraulic fluid. 
     
     
         39 . A gas compressor system as claimed in any one of  claims 31 to 38  wherein said at least one non-driving fluid component comprises natural gas. 
     
     
         40 . A gas compressor system as claimed in any one of  claims 31 to 38  wherein said at least one non-driving fluid component comprises a contaminant. 
     
     
         41 . A gas compressor system as claimed in any one of  claims 31 to 40 , wherein said at least one non-driving fluid component comprises hydrogen sulphide. 
     
     
         42 . A gas compressor system as claimed in any one of  claims 31 to 41  wherein said driving fluid is a hydraulic fluid. 
     
     
         43 . A gas compressor system as claimed in any one of  claims 31 to 42  wherein said buffer chamber is located immediately adjacent to said gas compression chamber. 
     
     
         44 . A gas compressor system as claimed in  claim 43  wherein said buffer chamber is located immediately adjacent to said driving fluid chamber. 
     
     
         45 . A gas compressor system as claimed in any one of  claims 31 to 44  wherein said driving fluid chamber and said buffer chamber are both located within said driving fluid cylinder. 
     
     
         46 . A gas compressor system as claimed in any one of  claims 31 to 45  wherein said buffer chamber is located on an opposite side of said driving fluid piston to said driving fluid chamber. 
     
     
         47 . A gas compressor as claimed in any one of  claims 31 to 46  wherein a volume of said driving fluid chamber and a volume of said buffer chamber overlap within said driving fluid cylinder. 
     
     
         48 . A gas compressor system as claimed in any one of  claims 31 to 47  further comprising a casing assembly located between said buffer chamber and said gas compression chamber. 
     
     
         49 . A gas compressor system as claimed in  claim 48  further comprising a seal device located at least partially within said casing, said seal device operable to inhibit gas from migrating from said gas compression chamber into said buffer chamber. 
     
     
         50 . A gas compressor system as claimed in  claim 48  further comprising a seal device located at least partially within said casing, said seal device operable to inhibit a non-gas component in said gas compression chamber from migrating from said gas compression chamber into said buffer chamber. 
     
     
         51 . A gas compressor system as claimed in  claim 49  wherein said seal device is also operable to inhibit a non-gas component from migrating from said gas compression chamber into said buffer chamber. 
     
     
         52 . A gas compressor system as claimed in  claim 48  further comprising a seal device located at least partially within a casing located between said gas compression chamber and said buffer chamber, said seal device operable to inhibit gas from migrating from said gas compression chamber into said buffer chamber; and wherein said seal device comprises a plurality of sealing rings mounted in said casing and engaging with an outer surface of said piston rod and an inner surface of said casing to provide a gas seal between said casing and said piston rod. 
     
     
         53 . A gas compressor system as claimed in any one of  claims 31 to 52  further comprising:
 a controller; 
 a proximity sensor associated with said driving fluid cylinder, said proximity sensor operable to detect a position of said driving fluid piston within said driving fluid cylinder and send a signal to said controller; 
 said controller operable in response to receiving said signal received from said proximity sensor, to control the flow of driving fluid into and out of said driving fluid chamber. 
 
     
     
         54 . A gas compressor system as claimed in  claim 53  wherein said proximity sensor is operable to detect a position of said piston rod within said driving fluid chamber at a position proximate an end point of a drive stroke of said driving fluid piston. 
     
     
         55 . A gas compressor system as claimed in any one of  claims 31 to 54  wherein in operation, said buffer chamber is filled with an inert gas maintained at a pressure that exceeds the pressure at any time within the gas compression chamber. 
     
     
         56 . A gas compressor system as claimed in  claim 55  wherein said inert gas comprises nitrogen. 
     
     
         57 . A gas compressor as claimed in  claim 55 or 56  further comprising a gas pressure regulator system in communication with said buffer chamber, said gas pressure regulator system operable to maintain the inert gas in said buffer chamber at a pressure that exceeds the pressure within the gas compression chamber during compression of the gas in the gas compression chamber. 
     
     
         58 . A gas compressor system as claimed in any one of  claims 31 to 54  wherein said buffer chamber is filled with air. 
     
     
         59 . A gas compressor system as claimed in  claim 58  wherein said air in said buffer chamber is in communication with a holding tank. 
     
     
         60 . A gas compressor system as claimed in any one of  claims 31 to 59  wherein said gas compression cylinder and said driving fluid cylinder are mounted on a support frame. 
     
     
         61 . A gas compressor system as claimed in  claim 60  wherein said gas compression cylinder, said driving fluid cylinder and said holding tank are mounted on a support frame. 
     
     
         62 . A gas compressor system as claimed in  claim 61  wherein said holding tank is integrated within said support frame. 
     
     
         63 . A gas compressor system as claimed in any one of  claims 31 to 62 , said system further comprising a driving fluid supply system operable to supply driving fluid to said driving fluid chamber to drive said driving fluid piston. 
     
     
         64 . A gas compressor system as claimed in  claim 63  wherein said driving fluid supply system comprises a pump unit and at least one fluid communication line operable for supplying pressurized driving fluid to said driving fluid chamber. 
     
     
         65 . A gas compressor system as claimed in  claim 63 or 64  wherein said driving fluid supply system is a closed loop system. 
     
     
         66 . A gas compressor system as claimed in any one of  claims 63 to 65  further comprising a controller for controlling said driving fluid supply system for controlling the flow of driving fluid to said driving fluid chamber. 
     
     
         67 . A gas compressor system as claimed in  claim 66  further comprising:
 a proximity sensor associated with said driving fluid cylinder, said proximity sensor operable to detect a position of said driving fluid piston within said driving fluid cylinder and send a signal to said controller; 
 said controller operable in response to receiving said signal received from said proximity sensor, and send a signal to said driving fluid supply system to control the flow of driving fluid into and out of said driving fluid chamber. 
 
     
     
         68 . A gas compressor system as claimed in any one of  claims 31 to 67  further comprising a gas communication system operable to supply gas to said gas compression chamber and operable to remove gas compressed by said gas piston in gas compression chamber, from said gas compression chamber. 
     
     
         69 . A gas compressor as claimed in any one of  claims 31 to 68  wherein:
 said driving fluid chamber is a first driving fluid cylinder having a first driving fluid chamber and a first driving fluid piston movable within said first driving chamber; 
 said buffer chamber is a first buffer chamber located between a first driving fluid chamber and a first section of said gas compression chamber, 
 said gas compressor further comprises:
 a second driving fluid cylinder having a second driving fluid chamber operable in use for containing a driving fluid and a second driving fluid piston movable within said second driving fluid chamber, and wherein said second driving fluid cylinder is located on an opposite side of said gas compression cylinder as said first driving fluid cylinder; 
 a second buffer chamber located between said second driving fluid chamber and a second section of said gas compression chamber, said second section of said gas compression chamber being on an opposite side of said gas piston to said first section of said gas compression chamber in said gas compression cylinder, 
 
 said first buffer chamber is adapted to inhibit movement of a gas located within said first gas compression chamber section into said first driving fluid chamber; and 
 said second buffer chamber is adapted to inhibit movement of a gas located within said second gas compression chamber section, from said second gas compression chamber section into said second driving fluid chamber. 
 
     
     
         70 . A gas compressor system as claimed in  claim 69  further comprising a driving fluid supply system operable to supply driving fluid to said first driving fluid chamber to drive said first driving fluid piston and operable to supply driving fluid to said second driving fluid chamber to drive said second driving fluid piston. 
     
     
         71 . A gas compressor system as claimed in  claim 70  wherein said driving fluid supply system comprises a pump unit and at least one fluid communication line operable for supplying pressurized driving fluid to said driving fluid chambers. 
     
     
         72 . A gas compressor system as claimed in  claim 70 or 71  wherein said driving fluid supply system is a closed loop system. 
     
     
         73 . A gas compressor system as claimed in any one of  claims 70 to 72  further comprising a controller for controlling said driving fluid supply system for controlling the flow of driving fluid to said first and second driving fluid chambers. 
     
     
         74 . A gas compressor system as claimed in any one of  claims 69 to 73  wherein said piston rod that is fixedly connected to said first driving fluid piston, said gas piston and said second driving fluid piston, such that in operation when said driving fluid flows into said first driving fluid chamber said first driving fluid piston drives said first driving fluid piston such that said first driving fluid piston, said second driving fluid piston and said gas piston move together within said respective first driving fluid chamber, said second driving fluid chamber and said gas compression chamber, and such that in operation when said driving fluid flows into said second driving fluid chamber, said second driving fluid piston drives said second driving fluid piston such that said first driving fluid piston, said second driving fluid piston and said gas piston move together in an opposite direction within said respective first driving fluid chamber, said second driving fluid chamber and said gas compression chamber. 
     
     
         75 . A gas compressor as claimed in  claim 74  wherein a volume of said first driving fluid chamber and a volume of said first buffer chamber overlaps within said first driving fluid cylinder and a volume of said second driving fluid chamber and a volume of said second buffer chamber overlap within said second driving fluid cylinder. 
     
     
         76 . A gas compressor as claimed in  claim 74 or 75  wherein said piston rod extends from said first driving fluid piston through said first buffer chamber into said gas compression chamber to said gas piston and extends further through said second buffer chamber to said second driving fluid piston. 
     
     
         77 . A gas compressor as claimed in any one of  claims 69 to 76  wherein during operation, said first buffer chamber varies in length dependent upon the position of said first driving fluid piston in said first driving fluid cylinder and said second buffer chamber varies in length dependent upon the position of said second driving fluid piston in said second driving fluid cylinder. 
     
     
         78 . A gas compressor as claimed in  claim 77  wherein during operation, said first buffer chamber varies in length dependent upon the position of said first driving fluid piston in said first driving fluid cylinder and the minimum length of said first buffer chamber is greater than the stroke length of said gas piston, said piston rod and said first and second hydraulic fluid pistons. 
     
     
         79 . A gas compressor as claimed in  claim 78  wherein during operation, said second buffer chamber varies in length dependent upon the position of said second driving fluid piston in said second driving fluid cylinder and the minimum length of said second buffer chamber is greater than the stroke length of said gas piston, said piston rod and said first and second hydraulic fluid pistons. 
     
     
         80 . A gas compressor as claimed in any one of  claims 74 to 79  wherein said first buffer chamber is configured such that in operation, no portion of said piston rod that is received within said gas compression chamber will be received in a portion of said first hydraulic cylinder that receives hydraulic fluid and wherein said second buffer chamber is configured such that in operation, no portion of said piston rod that is received within said gas compression chamber will be received in a portion of said second hydraulic cylinder that receives hydraulic fluid. 
     
     
         81 . A gas compressor as claimed in any one of  claims 69 to 80  wherein said first driving fluid piston is operable to drive said gas piston in an opposite direction to said second driving fluid piston. 
     
     
         82 . A gas compressor system comprising:
 a first driving fluid cylinder having a first driving fluid chamber adapted for containing a first driving fluid therein, and a first driving fluid piston movable within said first driving fluid chamber;   a gas compression chamber adapted for holding a gas therein and a gas piston movable within said gas compression chamber;   a first buffer chamber located between said first driving fluid chamber and a first section of said gas compression chamber;   a second driving fluid cylinder having a second driving fluid chamber adapted for containing a second driving fluid therein, and a second driving fluid piston movable within said second driving fluid chamber;   a second buffer chamber located between said first driving fluid chamber and a second section of said gas compression chamber;   wherein said first buffer chamber is adapted to inhibit movement of at least one non-driving fluid component, when gas is located within a first section of said gas compression chamber, from said first section gas compression chamber section into said first driving fluid chamber;   wherein said second buffer chamber adapted to inhibit movement of at least one non-driving fluid component, when gas is located within a second section of said gas compression chamber, from said second section of said gas compression chamber into said second driving fluid chamber.   
     
     
         83 . A gas compressor systems as claimed in  claim 82  wherein said first buffer chamber is adapted such that during operation when gas is compressed in said first gas compression chamber section, said first buffer chamber is operable to inhibit movement of at least one non-driving fluid component, when gas is located within said first gas compression chamber section, from said first gas compression chamber into said first driving fluid chamber; and wherein said second buffer chamber is adapted such that during operation when gas is compressed in said second gas compression chamber section, said second buffer chamber is operable to inhibit movement of at least one non-driving fluid component, when gas is located within said second gas compression chamber section, from said second gas compression chamber section into said second driving fluid chamber. 
     
     
         84 . A gas compressor system as claimed in  claim 82 or 83  wherein said at least one non-driving fluid component in both of said first and second gas compression chamber sections comprises natural gas. 
     
     
         85 . A gas compressor system as claimed in  claim 82, 83 or 84  wherein said at least one non-driving fluid component in both of said first and second gas compression chamber sections comprises a contaminant. 
     
     
         86 . A gas compressor system as claimed in any one of  claims 82 to 85 , wherein said at least one non-driving fluid component in both of said first and second gas compression chamber sections comprises hydrogen sulphide. 
     
     
         87 . A gas compressor system as claimed in any one of  claims 82 to 86  wherein said first buffer chamber is located adjacent to said first gas compression chamber section and said second buffer chamber is located adjacent to said second gas chamber section. 
     
     
         88 . A gas compressor system as claimed in any one of  claims 82 to 87  wherein said first driving fluid chamber and said first buffer chamber are both located within said first driving fluid cylinder. 
     
     
         89 . A gas compressor system as claimed in  claim 88  further comprising a first seal device operable to inhibit gas in said first gas compression chamber section from migrating from said first gas compression chamber section into said first buffer chamber. 
     
     
         90 . A gas compressor system as claimed in  claim 89  further comprising a second seal device operable to inhibit gas in said second gas compression chamber section from migrating from said second gas compression chamber section into said second buffer chamber. 
     
     
         91 . A gas compressor system as claimed in  claim 88, 89 or 90  wherein said second driving fluid chamber and said second buffer chamber are both located within said second driving fluid cylinder. 
     
     
         92 . A gas compressor system as claimed in any one of  claims 82 to 91  wherein said first buffer chamber is located on an opposite side of said first driving fluid piston to said first driving fluid chamber. 
     
     
         93 . A gas compressor system as claimed in  claim 92  wherein said second buffer chamber is located on an opposite side of said second driving fluid piston to said second driving fluid chamber. 
     
     
         94 . A gas compressor system as claimed in any one of  claims 82 to 93  wherein said gas compression chamber is formed in a gas compression cylinder located between said first driving fluid cylinder and said second driving fluid cylinder. 
     
     
         95 . A gas compressor system as claimed in  claim 94  wherein first driving fluid cylinder, said gas compression cylinder and said second driving fluid cylinder are interconnected to each other. 
     
     
         96 . A gas compressor system as claimed in any one of  claims 82 to 95  further comprising a piston rod that is fixedly connected to said first driving fluid piston, said gas piston, and said second driving fluid piston such that in operation, said driving fluid flowing into said first driving fluid chamber drives said first driving fluid piston in a first direction, and said driving fluid entering said second driving fluid chamber drives said second driving fluid piston in a second direction opposite to said first direction, and said first fluid driving piston, said gas piston and said second fluid driving piston are operable to move together within said respective first driving fluid cylinder, said gas compression cylinder and said second driving fluid cylinder, in reciprocating movement. 
     
     
         97 . A gas compressor as claimed in  claim 96  wherein a volume of said first driving fluid chamber and a volume of said first buffer chamber overlap within said first driving fluid cylinder and a volume of said second driving fluid chamber and a volume of said second buffer chamber overlap within said second driving fluid cylinder. 
     
     
         98 . A gas compressor as claimed in  claim 96 or 97  wherein said piston rod extends from said first driving fluid piston through said first buffer chamber into said gas compression chamber to said gas piston and extends further through said second buffer chamber to said second driving fluid piston. 
     
     
         99 . A gas compressor as claimed in any one of  claims 96 to 98  wherein during operation, said first buffer chamber varies in length dependent upon the position of said first driving fluid piston in said first driving fluid cylinder and said second buffer chamber varies in length dependent upon the position of said second driving fluid piston in said second driving fluid cylinder. 
     
     
         100 . A gas compressor as claimed in  claim 99  wherein during operation, said first buffer chamber varies in length dependent upon the position of said first driving fluid piston in said first driving fluid cylinder and the minimum length of said first buffer chamber is greater than the stroke length of said gas piston, said piston rod and said first and second hydraulic fluid pistons. 
     
     
         101 . A gas compressor as claimed in  claim 100  wherein during operation, said second buffer chamber varies in length dependent upon the position of said second driving fluid piston in said second driving fluid cylinder and the minimum length of said second buffer chamber is greater than the stroke length of said gas piston, said piston rod and said first and second hydraulic fluid pistons. 
     
     
         102 . A gas compressor as claimed in any one of  claims 96 to 101  wherein said first buffer chamber is configured such that in operation, no portion of said piston rod that is received within said gas compression chamber will be received in a portion of said first hydraulic cylinder that receives hydraulic fluid and wherein said second buffer chamber is configured such that in operation, no portion of said piston rod that is received within said gas compression chamber will be received in a portion of said second hydraulic cylinder that receives hydraulic fluid. 
     
     
         103 . A gas compressor system as claimed in any one of  claims 82 to 102 , further comprising a first casing located between said first buffer chamber and said first gas compression chamber section and further comprising a second casing located between said second buffer chamber and said second gas compression chamber section. 
     
     
         104 . A gas compressor system as claimed in  claim 103  further comprising a first seal device located at least partially within said first casing, said first seal device operable to inhibit gas from migrating from said gas compression chamber into said first buffer chamber; and further comprising a second seal device located at least partially within said second casing, said second seal device operable to inhibit gas from migrating from said gas compression chamber into said second buffer chamber. 
     
     
         105 . A gas compressor system as claimed in  claim 104  further comprising a first seal device located at least partially within said first casing, said first seal device operable to inhibit a non-gas component in said first gas compression chamber section from migrating from said first gas compression chamber section into said first buffer chamber. 
     
     
         106 . A gas compressor system as claimed in  claim 105  further comprising a second seal device located at least partially within said second casing, said second seal device operable to inhibit a non-gas component in said second gas compression chamber section from migrating from said second gas compression chamber section into said second buffer chamber. 
     
     
         107 . A gas compressor system as claimed in  claim 106  wherein said first and second seal devices each further comprise a rod wiper operable to remove contaminants that may deposited onto said piston rod, from a portion of said piston rod as said portion of said piston rod moves from within respective said first and second gas compression chamber seconds into respective said first and second casings. 
     
     
         108 . A gas compressor system as claimed in any one of  claims 82 to 107  further comprising:
 a controller; 
 a first proximity sensor associated with said first driving fluid cylinder, said first proximity sensor operable to detect a position of said first driving fluid piston within said first driving fluid cylinder and send a signal to said controller; 
 a second proximity sensor associated with said second driving fluid cylinder, said first second proximity sensor operable to detect a position of said second driving fluid piston within said second driving fluid cylinder and send a signal to said controller; 
 said controller operable in response to receiving said signal received from said first proximity sensor, to control the flow of driving fluid into and out of said first driving fluid chamber and operable in response to receiving said signal received from said second proximity sensor, to control the flow of driving fluid into and out of said second driving fluid chamber. 
 
     
     
         109 . A gas compressor system as claimed in  claim 108  wherein said first proximity sensor is operable to detect a position of said first driving fluid piston within said first driving fluid chamber at a position proximate an end point of a drive stroke of said first driving fluid piston and said second proximity sensor is operable to detect a position of said second driving fluid piston within said second driving fluid chamber at a position proximate an end point of a drive stroke of said first driving fluid piston. 
     
     
         110 . A gas compressor system as claimed in any one of  claims 82 to 109  wherein in operation, said first and second buffer chamber each contain an inert gas maintained at a pressure that exceeds the pressure within the respective first and second gas compression chambers sections during compression of gas in said first and second gas compression chamber sections. 
     
     
         111 . A gas compressor system as claimed in  claim 110  wherein said inert gas comprises nitrogen. 
     
     
         112 . A gas compressor as claimed in  claim 110 or 111  further comprising a gas pressure regulator system in communication with said first and second buffer chambers, said gas pressure regulator system operable to maintain the inert gas in said first and second buffer chambers at pressures that exceeds the respective pressure within the first and second gas compression chamber sections during compression of gas in said first and second gas compression chamber sections. 
     
     
         113 . A gas compressor system as claimed in any one of  claims 82 to 112  wherein each of said first and second buffer chambers contains air. 
     
     
         114 . A gas compressor as claimed in  claim 113  wherein said air is pressurized to a pressure that exceeds the respective pressure within the first and second gas compression chamber sections during compression of gas in said first and second gas compression chamber sections. 
     
     
         115 . A gas compressor system as claimed in  claim 113 or 114  wherein said air in said buffer chamber is in communication with a holding tank. 
     
     
         116 . A gas compressor system as claimed in  claim 113, 114 or 115  wherein said holding tank and said first and second buffer chambers are in a closed system. 
     
     
         117 . A gas compressor system as claimed in any one of  claims 82 to 115  wherein said first and second buffer chambers are in a closed system. 
     
     
         118 . A gas compressor system as claimed in any one of  claims 82 to 117  wherein said gas compression cylinder and said first and second driving fluid cylinder are supported on a support frame with said gas compression cylinder positioned between said first and second driving fluid cylinders. 
     
     
         119 . A gas compressor system as claimed in  claim 115  wherein said holding tank, said gas compression cylinder and said first and second driving fluid cylinder are supported on a support frame with said gas compression cylinder positioned between said first and second driving fluid cylinders and wherein said gas compression cylinder, said driving fluid cylinder and said holding tank are mounted on a support frame. 
     
     
         120 . A gas compressor system as claimed in  claim 119  wherein said holding tank is integrated within said support frame. 
     
     
         121 . A gas compressor system as claimed in any one of  claims 82 to 120  further comprising a driving fluid supply system operable to supply driving fluid to said first driving fluid chamber to drive said first driving fluid piston and operable to supply driving fluid to said second driving fluid chamber to drive said second driving fluid piston. 
     
     
         122 . A gas compressor system as claimed in  claim 121  wherein said driving fluid supplied to said first fluid driving chamber and the driving fluid supplied to said second fluid driving chamber are part of driving fluid supply circuit. 
     
     
         123 . A gas compressor system as claimed in  claim 121 or 122  wherein said driving fluid supply system comprises a pump unit and at least two fluid communication lines, operable for supplying pressurized driving fluid to each of said first and second driving fluid chambers. 
     
     
         124 . A gas compressor system as claimed in  claim 121, 122 or 123  wherein said driving fluid supply system is a closed loop system. 
     
     
         125 . A gas compressor system as claimed in any one of  claims 121 to 124  further comprising a controller for controlling said driving fluid supply system for controlling the flow of driving fluid to and from said first and second driving fluid chambers. 
     
     
         126 . A gas compressor system as claimed in  claim 125  further comprising:
 a proximity sensor associated with said driving fluid cylinder, said proximity sensor operable to detect a position of said driving fluid piston within said driving fluid cylinder and send a signal to a controller; 
 a controller operable in response to receiving said signal received from said proximity sensor, and send a signal to said driving fluid supply system to selectively control the flow of driving fluid into and out of said first and second driving fluid chamber to provide reciprocating movement of said first and second driving fluid pistons and said gas piston. 
 
     
     
         127 . A gas compressor system as claimed in any one of  claims 82 to 126  further comprising a gas supply system operable to supply gas to said gas compression chamber and operable to remove gas compressed by said gas piston in gas compression chamber, from said gas compression chamber. 
     
     
         128 . An oil well producing system comprising:
 a production tubing having a length extending along a well shaft that extends to an oil bearing formation;   a passageway extending along at least the well shaft, said passageway operable to supply natural gas to a gas supply line, said gas supply line in communication with a gas compression chamber of a gas compressor system, said gas compressor system comprising any of the gas compressor systems of claims  31  to  127 .   
     
     
         129 . A system as claimed in  claim 128  further comprising a casing surrounding the production tubing and extending along at least part of the length of the production tubing and wherein the passageway extends between an outer surface of said production tubing and an inner surface of said casing. 
     
     
         130 . A gas compressor comprising:
 a driving fluid cylinder having a driving fluid chamber operable for containing a driving fluid therein and a driving fluid piston movable within said driving fluid chamber;   a gas compression cylinder having a gas compression chamber operable for holding a gas therein and a gas piston movable within said gas compression chamber;   a buffer chamber located between said driving fluid chamber and said gas compression chamber, said buffer chamber configured and operable to inhibit movement of at least one non-driving fluid component from said gas compression chamber to substantially avoid contamination of said driving fluid, when gas is located within said gas compression chamber.   
     
     
         131 . A gas compressor comprising:
 a driving fluid cylinder having a driving fluid chamber operable for containing a driving fluid therein and a driving fluid piston movable within said driving fluid chamber;   a gas compression cylinder having a gas compression chamber operable for holding natural gas therein and a gas piston movable within said gas compression chamber;   a buffer chamber located between said driving fluid chamber and said gas compression chamber, said buffer chamber containing a buffer gas component so as to substantially avoid contamination of said driving fluid in said driving fluid chamber, when natural gas is located within said gas compression chamber.