Reservoir Pressure Monitoring

Abstract

A method of completing a wellbore that includes providing wellbore casing having shaped charges and permanent pressure gauges on an outer surface of the casing. In an example of use, the casing is inserted into the wellbore and cement is injected into an annulus formed between the casing and wellbore. The shaped charges are strategically deployed on the casing so they aim towards a wall of the wellbore and are spaced apart along the casing. Thus detonating the shaped charges creates perforations into a formation around the wellbore and places the pressure gauges into pressure communication with the formation. Pressure readings are delivered to the surface from the pressure gauges in the form of signals.

What is claimed is: 
     
         1 . A method of characterizing a subterranean formation comprising:
 a. providing a perforator in an annulus formed between a downhole tubular and a wall of a borehole that intersects the subterranean formation;   b. using the perforator to form a perforation through the wall and into the subterranean formation thereby communicating pressure in the subterranean formation to the annulus; and   c. estimating pressure in the subterranean formation by measuring pressure in the annulus.   
     
     
         2 . The method of  claim 1 , wherein step (c) is performed over a period of time and changes of pressure in the subterranean formation over the period of time are monitored. 
     
     
         3 . The method of  claim 1 , wherein the perforator comprises a device selected from the group consisting of a shaped charge, a perforating bullet, and a fluid jet. 
     
     
         4 . The method of  claim 1 , wherein the step of measuring pressure in the annulus comprises providing a pressure gauge in the annulus and monitoring an output from the pressure gauge. 
     
     
         5 . The method of  claim 3 , wherein the perforator comprises a housing and the perforation extends into the housing so that an inside of the housing is in pressure communication with the subterranean formation, and wherein an input to the pressure gauge is ported to the inside of the housing. 
     
     
         6 . The method of  claim 3 , wherein the perforator comprises a housing and the perforation extends into the housing so that an inside of the housing is in pressure communication with the subterranean formation, and wherein the pressure gauge is disposed inside the housing. 
     
     
         7 . The method of  claim 1 , wherein the subterranean formation includes multiple zones, the method further comprising performing steps (a)-(c) in at least two of the zones. 
     
     
         8 . The method of  claim 1 , further comprising providing cement in the annulus after step (a) and before step (b). 
     
     
         9 . A system for measuring pressure in a subterranean formation comprising:
 a perforator selectively disposed in an annulus formed between a downhole tubular and a wall of a wellbore;   a pressure gauge in pressure communication with the perforator; and   a coupling mounted on the pressure gauge attached to a signal line, so that when the perforator is initiated to create a perforation through the wall of the wellbore, the pressure gauge is brought into pressure communication with the formation and the pressure in the formation can be measured through the signal line.   
     
     
         10 . The system of  claim 9 , wherein the perforator comprises a perforating gun with a shaped charge and wherein cement is provided in the annulus and the perforation extends through a portion of the cement. 
     
     
         11 . The system of  claim 9 , further comprising tubing connected between the pressure gauge and the perforator for providing pressure communication between the pressure gauge and the perforator. 
     
     
         12 . The system of  claim 9 , further comprising a controller in communication with the pressure gauge through the signal line and in communication with the perforator through a signal line. 
     
     
         13 . The system of  claim 9 , wherein the downhole tubular comprises casing lining the wellbore and the perforator and the pressure gauge are each clamped to an outer surface of the casing. 
     
     
         14 . A method of measuring pressure in a formation adjacent a wellbore lined with casing, the method comprising:
 a. providing a shaped charge in an annulus between the casing and a wall of the wellbore;   b. providing a pressure gauge in the annulus and in pressure communication with the shaped charge;   c. forming a perforation in the formation by projecting a jet from the shaped charge into the formation from the annulus;   d. sensing pressure of the formation with the pressure gauge; and   e. directing a signal from the pressure gauge through a signal line that represents pressure sensed in the formation.   
     
     
         15 . The method of  claim 14 , wherein the shaped charge is included within a perforating gun having a housing, and the pressure gauge is in fluid communication with the shaped charge by a length of tubing connecting the housing and the pressure gauge. 
     
     
         16 . The method of  claim 14 , wherein the shaped charge is included within a perforating gun having a housing, and the pressure gauge is disposed in the housing. 
     
     
         17 . The method of  claim 14 , further comprising repeating steps (a)-(e), and wherein the perforation of step (c) is in a portion of the formation that is isolated from the portion of the formation of  claim 14  by a formation barrier.