Focused Formation Sampling via Guard Zone Segmentation
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Solution Overview
Problem
The challenge in obtaining uncontaminated formation fluid samples from subterranean formations is significant due to contamination from drilling mud filtrate, which complicates hydrocarbon fluid sampling and evaluation, leading to inaccurate and unreliable results.
Innovation Solution
A focused sampling system utilizing a single pump with a sample line, guard line, and common line configuration, along with fluid identification sensors and a flow restrictor, allows for the separation and collection of uncontaminated formation fluid by managing fluid flow rates and preventing contamination entry, enabling efficient and pure sample collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fluid is sampled through the sidewalls of the wellbore, then fluid sampling can be performed, but contamination of the formation fluid occurs
Solution Approach 1:
The sampling system is divided into separate functional zones: a sample zone with sample inlets for obtaining formation fluid, and a guard zone with guard inlets positioned radially outward for obtaining contaminated fluid. This segmentation allows independent handling of clean and contaminated fluid streams, enabling the sample zone to obtain pure formation fluid while the guard zone captures and isolates the contaminated outer fluid layer.
Solution Approach 2:
The contaminated fluid obtained through the guard inlets is extracted and directed to a separate guard line that bypasses the sample chamber. By removing the contaminated fluid from the sampling pathway before it can mix with the formation fluid, the system ensures that only uncontaminated fluid enters the sample chamber for analysis.
2Device complexity
If a single pump is used, then device complexity is reduced, but ability to separately manage sample and guard flows is limited
Solution Approach 1:
The system employs dynamic flow control through adjustable flow restrictors positioned in both the sample line and guard line. These restrictors can be adjusted to optimize the flow rates Qs and Qg independently, allowing the single pump to adaptively manage different flow conditions and maintain optimal sampling performance despite the simplified pump configuration.
Solution Approach 2:
A common line serves as an intermediary that receives fluid from both the sample line and guard line before delivering it to the single pump. This intermediary structure allows the single pump to handle combined flows while the upstream flow restrictors maintain independent control over the proportions of sample and guard fluids entering the common line.
3Object-affected harmful factors
If guard flow rate is increased, then contamination is better prevented, but sample collection efficiency decreases
Solution Approach 1:
The system optimizes the flow rate parameters Qs (sample flow rate) and Qg (guard flow rate) by adjusting the flow restrictors to achieve the desired ratio Qg/Qs. This parameter optimization ensures that the guard flow is sufficient to prevent contamination while maintaining adequate sample collection rate, balancing contamination prevention with sampling productivity.
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 effectively minimizes contamination, ensuring formation fluid samples of desired purity are collected, enhancing the accuracy and reliability of hydrocarbon evaluation and reducing operational delays and costs.
Implementation Method 1
pumping, via a common pump, a combined flow of fluid from the sample zone and the guard zone
Implementation Method 2
The pump and the flow restrictor are operable to optimize a ratio QG/QS of the flow rate QG of fluid from the formation into the guard zone through the guard zone inlet and the flow rate QS of fluid from the formation into the sample zone through the sample zone inlet
Data Source
AI summary
A focused sampling method comprising: allocating fluid flow from a guard zone through a guard line and from a sample zone through a sample line, the guard zone being positioned at least partially concentrically about the sample zone and the guard zone, and the sample zone being in fluid communication with a formation; pumping, via a common line, a combined fluid flow from the formation through to a discard line for a pre-sampling time period, the combined flow comprising the fluid flow allocated from the guard zone into the guard line and the fluid flow allocated from the sample zone into the sample line; subsequent the pre-sampling time period, discontinuing flow from the guard line into the common line, such that the combined flow comprises only the fluid flow from the sample line; and introducing the combined flow comprising the fluid flow from the sample line into a sample chamber.