Core Sample Permeability Testing for Initial Pore Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for determining initial pore pressure in unconventional reservoirs are inefficient and resource-intensive, lacking accuracy and reliability.
Innovation Solution
A core sample test system and method that involves performing permeability operations on a core sample from a reservoir, changing effective stress, and analyzing the natural logarithm of permeability to determine initial pore pressure, utilizing a system with sensors and a control unit to process sensor feedback and generate graphs for precise measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wellbore tests are used to determine initial pore pressure, then measurement reliability is improved, but resource consumption and time cost increase significantly
Solution Approach 1:
The patent performs preliminary permeability measurements on core samples under varying effective stresses before actual reservoir evaluation. By pre-characterizing the permeability-stress relationship and identifying the turning point in the natural logarithm of permeability versus effective stress curve, the method prepares essential data in advance, eliminating the need for time-consuming wellbore tests during field operations.
Solution Approach 2:
The patent creates a laboratory copy of reservoir conditions by conducting permeability tests on core samples under controlled effective stress environments. Instead of performing invasive wellbore tests in the actual reservoir, the method replicates stress conditions in the lab, measures permeability responses, and uses the turning point from the ln(k) versus effective stress curve to determine initial pore pressure, thereby avoiding time loss from field tests.
2Measurement precision
If conventional wellbore tests are performed to ensure accurate initial pore pressure determination, then measurement precision is improved, but resource consumption increases
Solution Approach 1:
The patent replaces energy-intensive wellbore tests with laboratory-based permeability measurements on core samples. By copying reservoir stress conditions in the lab and measuring the turning point in the natural logarithm of permeability versus effective stress relationship, the method achieves accurate initial pore pressure determination with significantly reduced resource consumption.
Solution Approach 2:
The patent substitutes mechanical wellbore testing operations with laboratory permeability measurement systems. Instead of performing invasive mechanical tests in the wellbore, the method uses controlled permeability experiments on core samples, analyzing the turning point in the ln(k) versus effective stress curve to obtain precise initial pore pressure data with lower energy and resource requirements.
3Measurement precision
If permeability measurements are conducted under multiple effective stress conditions, then determination accuracy of initial pore pressure is improved, but device complexity increases
Solution Approach 1:
The patent employs a dynamic testing approach where the effective stress is varied continuously during permeability measurements. By dynamically changing the effective stress condition and monitoring the corresponding permeability responses, the method captures the turning point in the natural logarithm of permeability versus effective stress curve, enabling accurate initial pore pressure determination without requiring an overly complex static multi-stage testing apparatus.
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 rapid and accurate determination of initial pore pressure without wellbore tests, enhancing measurement accuracy and reducing resource consumption.
Implementation Method 1
determining a natural logarithm of permeability of the core sample as a function of the effective stress
Implementation Method 2
changing an effective stress acting on the core sample... increasing the effective stress from a first value of effective stress that is less than the initial effective stress of the reservoir
Data Source
AI summary
A method includes performing, on a core sample obtained from a reservoir and positioned in a permeability measurement assembly that includes a flow inlet, a permeability operation by flowing a test fluid from the flow inlet and into the core sample and changing an effective stress acting on the core sample. The method also includes determining a natural logarithm of permeability of the core sample as a function of the effective stress, and determining, as a function of the natural logarithm of permeability of the core sample, an initial pore pressure of the reservoir.