Formation Tester Tool Assembly With Interchangeable Drawdown Assemblies
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Solution Overview
Problem
Current formation testing technologies, such as wireline formation testers and drill stem testing, face challenges including tool sticking, formation damage, difficulties in highly deviated wells, and inaccurate pressure measurements due to filtrate invasion and mudcake buildup, which hinder efficient and accurate evaluation of subterranean formations during oil and gas well drilling.
Innovation Solution
A formation tester tool integrated with a measurement while drilling (MWD) system that includes a formation probe assembly with a seal pad and drawdown assembly, designed to withstand drilling conditions, providing robust and accurate formation fluid sampling and pressure measurement while minimizing contamination from drilling fluids, and allowing for interchangeable drawdown assemblies to optimize sampling rates and volumes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wireline formation testers or drill stem testing are used to perform formation tests, then formation properties can be evaluated, but the drill string must be retracted and a separate work string or wireline tool string must be lowered into the well, interrupting the drilling process and adding significant time
Solution Approach 1:
The patent combines the formation testing equipment with the drill string, creating an integrated system that performs formation testing during drilling operations. The drawdown assembly is incorporated into the drill string architecture, allowing simultaneous drilling and formation evaluation without requiring separate work strings or wireline tools, thereby eliminating drilling process interruptions.
Solution Approach 2:
The integrated formation testing system enables continuous formation evaluation during the drilling process. The drawdown assembly remains operational throughout drilling, allowing continuous sampling and pressure measurement without stopping drilling operations, thus maintaining continuous useful action in both drilling and formation testing.
2Quantity of substance
If conventional formation testing equipment is used, then formation fluid samples can be obtained, but tool sticking or formation damage may occur due to harsh drilling conditions including vibration, torque, and exposure to drilling mud
Solution Approach 1:
The patent employs a flexible isolation pad that seals against the borehole wall to isolate the formation fluid sampling chamber from the harsh drilling environment. This flexible membrane protects the sampling system from vibration, torque, and drilling mud exposure while maintaining reliable formation fluid collection, thereby preventing tool sticking and formation damage.
Solution Approach 2:
The drawdown assembly acts as an intermediary between the drill string and the formation, providing a protected interface for formation fluid sampling. The assembly includes sealed chambers and valves that shield the sensitive sampling components from harsh drilling conditions while maintaining reliable connection to the formation, thus preventing tool sticking and formation damage.
3Measurement precision
If significant time passes before formation testing engagement, then formation pressure measurement accuracy is affected by filtrate invasion and mudcake buildup
Solution Approach 1:
The integrated formation testing system performs formation evaluation immediately during drilling operations, before filtrate invasion and mudcake buildup can significantly affect formation pressure measurements. The drawdown assembly is positioned and operational at the drilling front, enabling preliminary and continuous formation testing without delayed engagement, thus maintaining measurement accuracy.
4Reliability
If wireline formation testers are used with packers, then zonal isolation can be achieved, but the packers must be placed closer together for efficient testing, increasing device complexity
Solution Approach 1:
The patent extracts the zonal isolation function from the drill string and implements it at the formation interface through the drawdown assembly's sealed chamber design. The isolation pad and sealed chamber provide localized zonal isolation at the formation contact point without requiring multiple packers in the drill string, thereby reducing device complexity while maintaining reliable zonal isolation.
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
Enables efficient and accurate formation testing during drilling operations, reducing tool sticking and formation damage, and improving measurement accuracy by maintaining a seal against the borehole wall and using interchangeable drawdown assemblies to optimize sampling parameters.
Implementation Method 1
The isolation pad seals against the formation and around a hollow probe, which places an internal cavity in fluid communication with the formation. This creates a fluid pathway that allows formation fluid to flow between the formation and the formation tester while isolated from the borehole fluid.
Implementation Method 2
The valves or ports are then opened to allow flow from the formation to the tool for testing while the recorders chart static pressures.
Data Source
AI summary
A formation tester tool can include a longitudinal probe drill collar having a surface, a formation probe assembly located within the probe drill collar, the formation probe assembly including a piston reciprocal between a retracted position and an extended position beyond the probe drill collar surface, the piston being slidingly retained within a chamber, a seal pad located at an end of the piston, the seal pad including an outer surface defining a partial cylindrical surface. The piston includes an outer surface having non-circular cross-sectional shape and the chamber includes an inner surface having a non-circular shape similar to the shape of the piston outer surface. The formation tester tool can include interchangeable draw down assemblies and a flow bore having a curving path.