Downhole fluid-flow communication technique

Abstract

A method of wireless communication with a downhole assembly in absence of pressure pulse or hard wired communications. Tools and techniques for achieving such wireless communications are directed fluid-flow communication which may be utilized in circumstances where a completions assembly is open to the well in a pressure sense. Notably, a trigger is included with detection equipment which may be utilized to detect fluid-flow generated by surface equipment. In certain embodiments, such equipment may even be mounted exterior of completions equipment tubing through which fluid-flow communication is directed. Thus, wireless downhole communication capacity may even be provided without the need for obstructing tubing with such detection equipment.

1 . A downhole completions assembly for installation in a well at an oilfield, the assembly comprising:
 an application tool for performing an application at a downhole location in the well;   an actuation tool coupled to said application tool for driving the performing; and;   a trigger coupled to said actuation tool to initiate the driving and responsive to fluid-flow communication transmitted through the well from a surface of the oilfield.   
     
     
         2 . The assembly of  claim 1  wherein said actuation tool is a hydrostatic set module. 
     
     
         3 . The assembly of  claim 1  wherein said trigger is a first trigger, the assembly further comprising an additional trigger responsive to the communication for redundancy. 
     
     
         4 . The assembly of  claim 1  further comprising:
 a pump disposed at the surface for generating the fluid-flow; and 
 a control unit coupled to the pump for directing said pump. 
 
     
     
         5 . The assembly of  claim 1  wherein said application tool is one of a packer, a valve, a sliding sleeve, a fluid sampler, a measurement recorder, and a pyrotechnic device. 
     
     
         6 . The assembly of  claim 5  wherein the pyrotechnic device is a perforator. 
     
     
         7 . The assembly of  claim 5  further comprising production tubing with the packer disposed thereabout for downhole zonal isolation. 
     
     
         8 . A trigger of a downhole assembly deployed from a surface of an oilfield, the trigger configured for initiating driving of an application by an actuation tool of the assembly and comprising detection equipment for sensing fluid-flow communication from the surface for the initiating. 
     
     
         9 . The trigger of  claim 8  wherein the assembly comprises:
 tubing accommodating the actuation tool, the trigger coupled thereto; and 
 an application tool coupled to the actuation tool for the application. 
 
     
     
         10 . The trigger of  claim 9  wherein the fluid-flow communication is directed through an interior of said tubing and the trigger is disposed at an exterior location of said tubing. 
     
     
         11 . The trigger of  claim 10  wherein said detection equipment is one of calorimetric, acoustic, ultrasonic and electromagnetic. 
     
     
         12 . The trigger of  claim 8  wherein said detection equipment is one of calorimetric, acoustic, ultrasonic, electromagnetic, Venturi-based and flow-based tracer detection equipment. 
     
     
         13 . The trigger of  claim 12  wherein the calorimetric detection equipment comprises a heat source in the form of a thermal resistor. 
     
     
         14 . The trigger of  claim 13  wherein the resistor is configured to maintain a pre-determined temperature, a power level required to maintain the pre-determined temperature indicative of the fluid-flow communication. 
     
     
         15 . The trigger of  claim 13  wherein the detection equipment further comprises:
 a first temperature sensor disposed uphole of the resistor; and 
 a second temperature sensor disposed downhole of the resistor, a flow induced temperature gradient therebetween indicative of the fluid-flow communication. 
 
     
     
         16 . The trigger of  claim 15  wherein said sensors are one of platinum resistor temperature devices and thermocouples. 
     
     
         17 . A method of actuating a downhole tool at a location in a well from an oilfield surface, the method comprising:
 initiating a fluid-flow signal at the surface with equipment thereat; and   detecting the fluid-flow signal at a flow-meter of a trigger in the well coupled to an actuator.   
     
     
         18 . The method of  claim 17  further comprising utilizing the trigger to actuate the tool at the location with the actuator based on said detecting. 
     
     
         19 . The method of  claim 17  wherein said detecting further comprises:
 sampling periodic detections with the trigger in a sleep mode; and 
 activating a listening mode of the trigger for actuating the tool at the location with the actuator based on detections reaching a pre-determined substantially stable level. 
 
     
     
         20 . The method of  claim 19  further comprising:
 employing a time-delay between said detecting and the actuating; and 
 sending a fluid-flow cancellation communication with the equipment to terminate the actuating. 
 
     
     
         21 . The method of  claim 17  further comprising circulating fluid including the fluid-flow signal downhole and uphole within the well following said initiating to substantially avoid a net addition of fluid to the well. 
     
     
         22 . The method of  claim 17  further comprising discarding detections from said detecting which measure flow rate below a few centimeters per second. 
     
     
         23 . The method of  claim 17  further comprising discarding detections from said detecting which are substantially discontinuous. 
     
     
         24 . The method of  claim 17  wherein said initiating is of a first fluid-flow signal directed at the trigger, the method further comprising sending a second fluid-flow signal into the well with the equipment. 
     
     
         25 . The method of  claim 24  wherein the trigger is a first trigger, said sending comprising directing the second fluid-flow signal at a second trigger in the well. 
     
     
         26 . The method of  claim 17  wherein the surface is a seabed and the fluid-flow signal is initiated by equipment coupled to a well head thereat.