Method and system to drill out well completion plugs

Abstract

A system for controlling load on a downhole tool for drilling out wellbore plugs is provided. The system includes a downhole drilling tool connected with a drill string extending within a cased wellbore. A drilling fluid flows into a casing space of the cased wellbore from the downhole drilling tool or a distal end outlet of the drill string. A fluid back pressure system comprising a variable flow restriction device applies flow restriction in the casing space to restrict fluid flow therein. At least one sensor measures a drilling fluid pressure within the drill string and at least one second sensor measures the casing fluid pressure. A processor is adapted to monitor the drilling fluid pressure and the casing space fluid pressure during a drilling operation to adjust a mechanical load on the downhole drilling tool to drill out wellbore plugs based on a difference pressure value between the drilling fluid pressure and the casing space fluid pressure.

What is claimed is: 
     
         1 . A system for controlling load on a downhole tool of a well drilling equipment of an oil or gas rig, comprising:
 a downhole drilling tool, including a drill bit, connected in operable communication with a drill string extending within a wellbore, the drill string being adapted to permit a drilling fluid to flow to the downhole drilling tool, wherein the drilling fluid flows into an annular space from the downhole drilling tool or a distal end outlet of the drill string, the annular space being formed between the drill string and the wellbore wall;   a pump for pumping the drilling fluid from a drilling fluid tank through the drill string into the annular space;   a fluid back pressure system comprising a variable flow restriction device for applying flow restriction in the annular space to restrict fluid flow therein;   at least one first sensor disposed in operable communication with the drill string for measuring a drilling fluid pressure within the drill string;   at least one second sensor disposed in operable communication with the annular space for measuring an annular space fluid pressure therein; and   a processor adapted to monitor the drilling fluid pressure and the annular space fluid pressure during a drilling operation, to adjust a mechanical load on the downhole drilling tool based on a difference pressure value between the drilling fluid pressure and the annular space fluid pressure.   
     
     
         2 . The system of  claim 1 , wherein the wellbore is a cased wellbore. 
     
     
         3 . The system of  claim 2 , wherein the drilling operation includes a well bore plug drilling operation for drilling wellbore plugs within a cased wellbore. 
     
     
         4 . The system of  claim 3 , wherein the processor is further adapted to adjust the load in response to a change in the difference pressure value by at least one of an increase and a decrease beyond a selected pressure threshold. 
     
     
         5 . The system of  claim 3 , wherein the mechanical load is the weight of the drill string on the drill bit. 
     
     
         6 . A method of controlling load on a downhole tool of a well drilling equipment of an oil or gas rig, comprising:
 disposing a downhole drilling tool, including a drill bit, connected in operable communication with a drill string extending within a wellbore, the drill string being adapted to permit a drilling fluid to flow to the downhole drilling tool, wherein the drilling fluid flows into an annular space from the downhole drilling tool or a distal end outlet of the drill string, the annular space being formed between the drill string and the wellbore wall;   pumping the drilling fluid from a drilling fluid tank through the drill string into the annular space;   applying flow restriction in the annular space to restrict fluid flow therein using a fluid back pressure system comprising a variable flow restriction device;   disposing at least one first sensor in operable communication with the drill string for measuring a drilling fluid pressure within the drill string;   disposing at least one second sensor in operable communication with the annular space for measuring an annular space fluid pressure therein;   monitoring the drilling fluid pressure and the annular space fluid pressure by a processor during a drilling operation; and   advancing the drill string to add mechanical load on the downhole drilling tool based on a difference pressure value between the drilling fluid pressure and the annular space fluid pressure.   
     
     
         7 . The method of  claim 6 , wherein the step of advancing the drill string adds mechanical load on a wellbore plug within the wellbore. 
     
     
         8 . The method of  claim 7  further comprising drilling the wellbore plug within the wellbore. 
     
     
         9 . The method of  claim 8  further comprising adjusting the mechanical load in response to a change in the difference pressure value by at least one of an increase and a decrease beyond a selected pressure threshold. 
     
     
         10 . The method of  claim 8 , wherein the mechanical load is the weight of the drill string on the drill bit. 
     
     
         11 . A system to drill through at least one wellbore plug in a cased wellbore, the system comprising:
 a downhole motor connected to a tubing string;   a downhole cutting device hydraulically connected to the downhole motor;   a wellbore fluid pump for pumping a wellbore fluid through the tubing string, the wellbore fluid pump connected to the downhole motor for rotating the downhole cutting device while weight is simultaneously applied on the downhole cutting device, thereby enabling the downhole cutting device to contact and cut through the at least one wellbore plug in the cased wellbore;   a tubing pressure sensor connected to the tubing string for producing tubing pressure sensor data;   at least one casing pressure sensor installed in communication with the cased wellbore producing a casing pressure sensor data;   a processor connected to the tubing pressure sensor and the at least one casing pressure sensor; and   a data storage connected to the processor, the data storage comprising:
 computer instructions to instruct the processor to receive and store the tubing pressure sensor data and the casing pressure sensor data; 
 at least one differential pressure set point limit for the downhole motor; 
 computer instructions to instruct the processor to compare the tubing pressure sensor data to the casing pressure sensor data to calculate a measured differential pressure for the downhole motor; 
 computer instructions to instruct the processor to compare the measured differential pressure for the downhole motor to the at least one differential pressure set point limit of the downhole motor; and 
 computer instructions to instruct the processor to selectively transmit a message when the measured differential pressure for the downhole motor is either: (i) less than the at least one differential pressure set point limit for the downhole motor, (ii) equal to the at least one differential pressure set point limit for the downhole motor, or (iii) greater the at least one differential pressure set point limit for the downhole motor, 
 wherein the message is transmitted to an autodriller to advance the tubing string by operating a drawworks. 
   
     
     
         12 . The system of  claim 11 , further comprising a torque sensor in communication with the tubing string for transmitting torque sensor data to the processor and the data storage, the data storage further comprising: at least one torque limit and computer instructions for comparing torque sensor data to the at least one torque limit; and transmitting a torque message to start or stop rotation of the tubing string or change speed of rotation of the tubing string. 
     
     
         13 . The system of  claim 11 , further comprising:
 a hook load sensor positioned on a hook, the hook suspending the tubing string, the hook load sensor transmitting hook load data to the processor for storage in the data storage;   and wherein the data storage further comprising:
 at least one hook load limit; and 
   computer instructions for comparing hook load data to the at least one hook load limit, and selectively providing a hook load command transmitted to the autodriller to advance the tubing string by operating the drawworks.   
     
     
         14 . The system of  claim 11 , further comprising:
 a pump stroke counter in communication with the wellbore fluid pump to transmit pump stroke data to the processor for storage in the data storage;
 the data storage further comprising: 
   computer instructions to instruct the processor to store and receive the pump stroke data and to calculate flow rates of the wellbore fluid pump using the pump stroke data; and
 computer instructions to instruct the processor to transmit calculated flow rates using the pump stroke data. 
   
     
     
         15 . The system of  claim 11 , wherein the data storage further comprises:
 at least one casing pressure limit; and   computer instructions to instruct the processor to compare casing pressure sensor data to the at least one casing pressure limit and transmit a command to a casing choke valve to open, close, or partially close.   
     
     
         16 . The system of  claim 11 , wherein the data storage further comprises computer instructions to instruct the processor to log sensor data for post operational analysis. 
     
     
         17 . The system of  claim 11 , wherein the data storage further comprises computer instructions providing an operator dashboard and an administrative dashboard simultaneously for on-location and off-location monitoring and control of the system to drill sequentially through a plurality of wellbore plugs. 
     
     
         18 . The system of  claim 11 , wherein the data storage further comprises computer instructions providing an administrative dashboard configured to simultaneously monitor and control multiple systems to drill through multiple cased wellbores, each having a plurality of wellbore plugs. 
     
     
         19 . The system of  claim 11 , further comprising a video capture device connected to the processor for visually monitoring the tubing string. 
     
     
         20 . The system of  claim 11 , wherein the downhole cutting device is at least one of: a mill, a fixed face bit, and a roller cone bit. 
     
     
         21 . The system of  claim 11 , further comprising an additional casing pressure sensor. 
     
     
         22 . The system of  claim 11 , further comprising a network connected to the processor and the at least one client device connected to the network, wherein the message is also transmitted to the at least one client device. 
     
     
         23 . The system of  claim 11 , wherein the system drills through a plurality of wellbore plugs in a cased well. 
     
     
         24 . A method to drill through at least one wellbore plug in a cased wellbore including the steps of:
 connecting a downhole motor to a downhole cutting device;   connecting the downhole motor to a tubing string;   connecting the tubing string to a rig;   pumping wellbore fluid through the tubing string to power the downhole motor and rotate the downhole cutting device while simultaneously applying weight on the downhole cutting device as the downhole cutting device contacts the at least one wellbore plug;   drill through the at least one wellbore plug in the cased wellbore while controlling differential pressure of the downhole motor in the cased wellbore;   transmitting tubing pressure sensor data to a processor;   transmitting casing pressure sensor data to the processor;   comparing the tubing pressure sensor data to the casing pressure sensor data to calculate a measured differential pressure;   comparing the measured differential pressure for the downhole motor to at least one differential pressure set point limit of the downhole motor; and   selectively transmitting a message when the measured differential pressure for the downhole motor is either: (i) less than the at least one differential pressure set point limit for the downhole motor, (ii) equal to the at least one differential pressure set point limit for the downhole motor, or (iii) greater the at least one differential pressure set point limit for the downhole motor,   wherein the message is transmitted to at least one of:   an autodriller to advance the tubing string by operating a drawworks;   a display connected to the processor enabling an operator to manually advance the tubing string by operating the drawworks; and   at least one client device.