Downhole Fluid Analysis Pressure Control
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Solution Overview
Problem
Downhole fluid analysis in low mobility or tight reservoirs is challenging due to slow fluid flow rates and low concentration of hydrocarbons, making it difficult to conduct accurate analysis, especially when the reservoir is contaminated with mud, which complicates the detection of trace hydrocarbons.
Innovation Solution
A downhole tool system with a packer module that includes an upper and lower packer to seal a wellbore interval, an inlet to admit formation fluid into a flow line, a pump out module to extract the fluid, a fluid analysis module to analyze the fluid, and a sample module with an external fluid that can be transferred into the wellbore to increase pressure and improve analysis accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pump out module continuously pumps formation fluid from the inlet, then the fluid analysis module can continuously analyze formation fluid, but the interval pressure decreases making it difficult to detect trace hydrocarbons in low mobility reservoirs
Solution Approach 1:
The system implements periodic pumping cycles where the pump out module alternates between pumping formation fluid and pausing. During pause periods, the external fluid injection module injects external fluid into the interval to maintain pressure. This periodic operation allows continuous fluid analysis while preventing pressure depletion that would hinder trace hydrocarbon detection.
Solution Approach 2:
External fluid is introduced as an intermediary substance to maintain interval pressure during formation fluid pumping. The external fluid acts as a pressure support medium, allowing the pump out module to remove formation fluid for analysis without creating a pressure vacuum that would prevent trace hydrocarbon detection in low mobility reservoirs.
2Productivity
If the pump out module pumps at high rate to improve analysis speed, then productivity increases, but the low concentration of hydrocarbons in low mobility reservoirs makes detection more difficult
Solution Approach 1:
The system uses periodic pumping with controlled pause periods during which pressure is maintained or restored. This allows high-rate pumping to occur during active phases for productivity, while pause phases ensure sufficient pressure and fluid concentration for accurate trace hydrocarbon detection, thus resolving the contradiction between speed and precision.
Solution Approach 2:
The system monitors fluid composition and pressure conditions in real-time, using this feedback to adjust pumping rates and external fluid injection timing. When trace hydrocarbons are detected or pressure drops below optimal levels, the system automatically modulates pumping intensity, ensuring detection accuracy is maintained while maximizing overall analysis productivity.
3Measurement precision
If external fluid is transferred into the interval to increase pressure, then trace hydrocarbon detection improves, but the system complexity increases due to additional modules and operations
Solution Approach 1:
The external fluid injection module shares the same flow line infrastructure with the pump out module and fluid analysis module. The flow line serves multiple functions: removing formation fluid for analysis, injecting external fluid for pressure maintenance, and transporting both formation and external fluids. This multi-functionality reduces overall system complexity despite adding pressure control capability.
Solution Approach 2:
The system combines the pump out module and external fluid injection module into a coordinated system that shares common flow lines and control mechanisms. By merging these functions and using integrated control logic that manages both pumping and injection operations through unified pressure and flow management, the system reduces operational complexity while achieving improved trace hydrocarbon detection.
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
The system effectively increases the interval pressure and enhances the ability to detect trace hydrocarbons by recharging the wellbore with a compatible external fluid, improving the accuracy of downhole fluid analysis in low mobility reservoirs.
Implementation Method 1
an upper packer and a lower packer configured to seal an interval of the wellbore
Implementation Method 2
a pump out module configured to pump the formation fluid from the inlet
Implementation Method 3
transfer the external fluid from the sample chamber to the interval via the flowline and the inlet
Data Source
AI summary
The present disclosure relates to a system that includes a downhole tool that includes a packer module with an inlet disposed between an upper packer and a lower packer configured to seal an interval of a wellbore. The inlet is configured to admit a formation fluid disposed in the interval. The downhole tool also includes a pump out module, a fluid analysis module, and a sample module including a sample chamber containing an external fluid. The downhole tool also includes a data processing system configured to identify a composition of the formation fluid and includes one or more tangible, non-transitory, machine-readable media including instructions to identify a condition indicating stopping the pump out module, transfer the external fluid from the sample chamber to the interval the inlet, resume pumping of the formation fluid from the inlet via the pump out module, and output the composition of the formation fluid.