Well Barrier Pressure Testing for Production Casing Integrity
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Solution Overview
Problem
Existing well completion technologies fail to adequately test downhole barriers, leading to uncertainty about their effectiveness in preventing oil leaks during production, as seen in the Deepwater Horizon oil spill.
Innovation Solution
A comprehensive barrier testing method involving pressure testing of various components, including production casings, packers, and safety valves, to ensure integrity by maintaining constant pressures during predetermined time periods, with additional steps to expand annular barriers and flush drilling mud.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If comprehensive pressure testing of multiple barriers is performed, then well integrity and safety are improved, but testing time and operational complexity increase
Solution Approach 1:
The testing process is segmented into distinct phases, each targeting specific barriers (production casing, packers, safety valves, annular barriers). This allows systematic verification of each component's integrity while maintaining an organized workflow that reduces overall testing complexity despite the comprehensive nature of the testing regime.
Solution Approach 2:
Pressure testing is performed as a preliminary action before production initiation. All barriers are tested and documented for integrity before the well enters production phase, ensuring that safety verification is completed in advance rather than during or after production problems arise.
2Measurement precision
If multiple barriers are tested individually, then testing accuracy and reliability are improved, but the number of testing steps and operational complexity increase
Solution Approach 1:
A universal testing methodology is applied that can verify multiple different barrier types (metal casings, elastomeric packers, safety valves, annular barriers) using the same fundamental pressure testing principle. This multi-functional approach maintains testing accuracy across diverse barrier types while reducing procedural complexity by using a consistent testing framework rather than separate specialized procedures for each barrier type.
Solution Approach 2:
The testing procedure incorporates feedback mechanisms where pressure maintenance over predetermined time periods provides direct information about barrier integrity. This feedback loop allows accurate assessment of each barrier's sealing effectiveness while simplifying the interpretation of test results through a clear pass/fail criterion based on pressure stability.
3Reliability
If annular barriers are expanded to abut the borehole wall, then sealing effectiveness is improved, but the risk of cement displacement and unwanted pockets increases
Solution Approach 1:
Cement is placed in the annular space before the annular barriers are expanded. This preliminary cement placement ensures that the annular space is filled with a sealing material that can accommodate the barrier expansion without creating harmful displacement effects, as the cement is already in position to provide sealing rather than being displaced during expansion.
Solution Approach 2:
The cement acts as a cushioning material that absorbs and distributes the forces generated during annular barrier expansion. By having the cement in place beforehand, the expansion forces are cushioned and distributed through the cement rather than creating concentrated displacement forces that would push cement into unwanted pockets or fractures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures the integrity of well barriers by confirming their functionality, reducing the risk of oil leaks and ensuring safe production by documenting the integrity of the well before production initiation.
Implementation Method 1
the annular barriers of the intermediate casing are expanded to abut the wall of the borehole
Implementation Method 2
testing the annular barriers by monitoring the pressure increase for a period of time
Data Source
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AI summary
The present invention relates to a barrier testing method for testing a production casing in a borehole. The method is applied before initiating production in a well and comprises the steps of connecting a drill pipe with a first end of a first production casing having annular barriers, which annular barriers comprise a tubular part forming part of the casing and an expandable sleeve circumferenting the tubular part, thereby defining an expandable space; inserting the drill pipe and the first production casing via a drill head arranged at a top of the well into an intermediate casing extending in a first part of the borehole closest to the top of the well and at least part of the first production casing into a second part of the borehole; sealing a second end of the first production casing; pressurising the first production casing from within and expanding one or more of the expandable sleeves of the annular barriers to abut a wall of the borehole; pressurising the first production casing from within to a predetermined pressure; and testing the first production casing after expansion by measuring if the predetermined pressure is kept constant during a predetermined time period. Furthermore, the invention relates to a completion system for oil production from a well and to an oil production facilitated by the method barrier testing method.