Coring Assembly Gas Detection for Acid Gas Analysis
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Solution Overview
Problem
Conventional methods for detecting acid gases like hydrogen sulfide (H2S) and carbon dioxide (CO2) in subterranean formation fluids are unreliable due to reaction with downhole tools and contamination from drilling fluids, especially in high-pressure and deep wells, leading to inaccurate surface analysis.
Innovation Solution
A coring assembly with an inner core barrel and gas detectors positioned to capture and analyze core samples from the formation, allowing liberated gases to migrate to a gas cap where they can be detected without exposure to drilling fluid chemicals, providing an undisturbed sample of formation gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional downhole fluid sampling tools are used to collect formation fluid samples, then samples can be obtained for surface analysis, but the measured values may not be representative due to reactions with metals in downhole tools and contamination from drilling fluids
Solution Approach 1:
The invention extracts and isolates the formation fluid sample collection process from the conventional downhole sampling system. By using a coring assembly that captures formation fluid within the core sample matrix and transports it to the surface without exposure to drilling fluids or reactive metal surfaces, the sample integrity is preserved. The core sample acts as a protective container that extracts the formation fluid from the hostile downhole environment.
Solution Approach 2:
The invention introduces the core sample as an intermediary medium between the formation fluid and the analysis system. The core sample matrix serves as a protective intermediary that prevents direct contact between the formation fluid and reactive metals or drilling fluids, thereby preserving the original gas composition for accurate analysis.
2Productivity
If drilling fluids are used during coring operations, then the coring process can proceed, but residual drilling fluids contaminate the formation fluid samples and neutralize acid gases like H2S
Solution Approach 1:
The invention segments the coring system into distinct zones: the core sample chamber that isolates formation fluid, the annular space that contains drilling fluid, and the gas detection zone. This segmentation prevents mixing between drilling fluids and formation fluids, allowing coring operations to proceed while preserving sample integrity for accurate acid gas detection.
Solution Approach 2:
The invention extracts the formation fluid sample from the drilling fluid environment by capturing it within the core sample matrix during coring operations. The core sample acts as a separate compartment that extracts and protects the formation fluid from contamination by drilling fluids, enabling subsequent accurate analysis of acid gas concentrations.
3Adaptability or versatility
If conventional fluid sampling tools are used in high-pressure and temperature wells, then samples can be obtained, but it may not be possible to use some tools due to extreme conditions
Solution Approach 1:
The invention makes the coring assembly multi-functional by enabling it to both capture core samples and simultaneously collect formation fluid samples for gas analysis. This universal approach allows the same downhole tool to operate in extreme high-pressure and temperature conditions while providing reliable formation fluid sampling, eliminating the need for separate specialized sampling tools.
4Loss of information
If downhole formation fluid samples are collected for later surface analysis, then chemical and physical analysis can be performed, but the analysis may be inaccurate due to reactions and contamination during transport
Solution Approach 1:
The invention performs preliminary action by detecting and analyzing acid gases directly at the surface immediately upon retrieval of the core sample, before any potential contamination or compositional changes can occur. The gas detection system is positioned to analyze formation fluids as soon as they are liberated from the core sample, preserving the original formation conditions and gas concentrations.
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 accurate detection and quantification of acid gases in formation fluids, reducing the risk of premature equipment failure and improving well economics by providing reliable, representative data of gas concentrations.
Implementation Method 1
The detector is configured to react with a predetermined concentration of acid gas to produce a predetermined signal
Data Source
AI summary
A method for detecting the presence of an acid gas in a formation fluid from a subterranean formation comprises (a) lowering a coring assembly into a wellbore. The coring assembly including an outer core barrel and an inner core barrel disposed within the outer core barrel. The inner core barrel has an upper end, a lower end opposite the upper end, and a core sample chamber extending axially from the lower end. In addition, the method comprises (b) capturing a core sample from the subterranean formation within the sample chamber. Further, the method comprises (c) raising the coring assembly to the surface after (b). Still further the method comprises (d) contacting a formation fluid in the sample chamber with at least one detector during (c). Moreover, the method comprises (e) detecting the presence of a formation acid gas in the formation fluid with the at least one detector during (c).