Appraisal Well Injection Testing for Thermal Stress Calibration
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Solution Overview
Problem
Current reservoir models rely heavily on core sample data, which lacks scalability for thermal stress measurements, and existing injection testing methods only determine fluid properties and formation damage, failing to account for thermal stress effects on fracture pressure variations in wells.
Innovation Solution
A method involving downhole sensors to measure pressure and temperature during fluid injection, varying flow rates, and fitting models to estimate thermal stress characteristics, which are then used to determine optimized injection parameters, including perforation length, fluid temperature, and injection volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If core sample data is used to construct reservoir models, then the models can be built with available data, but the measurements cannot scale from laboratory to well conditions and thermal stress effects cannot be adequately captured
Solution Approach 1:
The patent performs injection testing at an appraisal well before the main development phase to preliminarily determine thermal stress characteristics. This preliminary action allows the thermal stress parameter to be obtained in advance, avoiding the need to scale from core samples later and enabling more accurate reservoir models from the outset.
Solution Approach 2:
The patent uses an appraisal well as an intermediary between core sample analysis and main development wells. By conducting injection tests at the appraisal well, thermal stress characteristics are measured in situ under actual reservoir conditions, serving as a bridge that translates laboratory data into field-applicable parameters without requiring direct scaling.
2Loss of information
If injection testing is performed to determine fluid properties and formation damage, then well productivity can be assessed, but thermal stress effects on fracture pressure variations are not determined
Solution Approach 1:
The patent performs injection testing at an appraisal well before the main development phase to preliminarily determine thermal stress characteristics. This preliminary action allows the thermal stress parameter to be obtained in advance, avoiding the need to scale from core samples later and enabling more accurate reservoir models from the outset.
Solution Approach 2:
The patent uses pressure measurements during injection testing to provide feedback on thermal stress effects. By monitoring pressure variations in response to temperature changes during injection, the system continuously refines the thermal stress parameter estimation, which then feeds back into optimizing injection parameters for improved recovery.
3Loss of time
If conventional injection parameters are used without thermal stress calibration, then injection programs can start quickly, but injection efficiency is reduced due to unoptimized parameters
Solution Approach 1:
The patent performs injection testing at an appraisal well before the main development phase to preliminarily determine thermal stress characteristics. This preliminary action allows the thermal stress parameter to be obtained in advance, avoiding the need to scale from core samples later and enabling more accurate reservoir models from the outset.
Solution Approach 2:
The patent changes injection parameters (temperature, pressure, flow rate) during injection testing to observe their effects on thermal stress responses. By systematically varying these parameters and measuring the resulting pressure changes, the thermal stress parameter is calibrated, which then enables optimized injection parameters for the main development phase.
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 more accurate calibration of reservoir models, improving injection efficiency by accounting for thermal stress effects and ensuring efficient fracturing, thereby enhancing hydrocarbon recovery.
Implementation Method 1
locating at least one downhole sensor to measure pressure in the well
Implementation Method 2
on injecting a cool fluid into warm subterranean reservoir, a cooling effect will occur around the injector. This alters the stresses in the region with altered temperature
Data Source
Figure 1~2
Figure 3~4
AI summary
A method for providing a well injection program in which injection testing is performed on an appraisal well. An appraisal well is selected, downhole sensors are located in the well to measure pressure and temperature, water is injected into the well in a series of step rate tests or injection cycles, the data is modelled to determine a thermal stress characteristic of the well and by reservoir modelling the optimum injection parameters are determined for the well injection program to provide for maximum recovery. This overcomes the need for making thermal stress characteristic measurements on core samples.