Downhole Formation Testing Fluid Chamber with Buffer and Flow Control
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Solution Overview
Problem
Determining the minimum horizontal stress of low permeability formations, such as shale, is challenging due to difficulties in accurately measuring the flowback rate and volume of injected fluid, which can damage downhole tool components and lead to inaccurate fracture pressure closure measurements.
Innovation Solution
A downhole tool with a fluid sample module featuring a buffer fluid and flow control device that separates injected fluid from tool components, controlling the flowback rate and using the buffer fluid's displaced volume to determine closure pressure, thereby enabling accurate measurement of minimum horizontal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flowback fluid is directly received from the formation, then measurement of minimum horizontal stress can be obtained, but tool components may be damaged by solids in the flowback fluid
Solution Approach 1:
A buffer fluid is introduced as an intermediary substance between the flowback fluid and the tool components. The buffer fluid receives the flowback fluid through a fluid chamber, preventing direct contact between solids in the flowback fluid and sensitive tool components while enabling indirect measurement of closure pressure through piston displacement.
2Measurement precision
If flowback rate is not controlled, then measurement process is simpler, but measurement accuracy deteriorates due to inability to accurately determine closure pressure
Solution Approach 1:
A flow control device is implemented to dynamically regulate the flowback rate of fluid into the buffer fluid chamber. This controlled flow rate enables accurate determination of closure pressure by managing the timing and rate at which the piston is displaced, while the system remains adaptable to varying formation conditions.
3Reliability
If buffer fluid is used to protect components, then component damage is reduced, but device complexity increases due to additional fluid chamber and piston mechanisms
Solution Approach 1:
The buffer fluid chamber serves multiple functions simultaneously: it acts as a protective barrier between flowback fluid and tool components, provides a controlled environment for pressure measurement, and enables piston displacement for closure pressure determination. This multi-functionality reduces the need for separate protective mechanisms.
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
This approach allows for precise determination of minimum horizontal stress in low permeability formations by controlling fluid flowback and using a buffer fluid to mitigate component damage and improve measurement accuracy.
Implementation Method 1
the piston is configured to move toward a fluid chamber outlet to displace the fluid in response to a flow of the flowback fluid into the fluid chamber
Data Source
AI summary
A downhole acquisition tool having a formation testing module is provided. The formation testing module includes a fluid chamber comprising a piston and configured to store a fluid and to receive a flowback fluid from a geological formation, wherein the fluid is substantially free of solids. Additionally, the formation testing tool has a first conduit fluidly coupled to the fluid chamber and extending from a flowback conduit and a first outlet of the formation testing module, wherein the flowback conduit is configured fluidly coupled to the geological formation. and configured to receive the flowback fluid from the geological formation, and wherein the first conduit is configured to receive the flowback fluid from the flowback conduit. Further, the formation testing module has a first flow control device positioned downstream from the fluid chamber, wherein the first flow control device is configured to control a flow of the fluid exiting the fluid chamber.