Coreflood Evaluation of Gel-Foam Conformance in Heterogeneous Cores
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Solution Overview
Problem
Heterogeneity in oil and gas reservoirs, such as fractures, faults, and thief zones, poses challenges for efficient hydrocarbon recovery, and existing conformance control methods like foams and gels face stability issues under reservoir conditions, leading to inefficiencies in sweep efficiency and conformance control during improved oil recovery processes.
Innovation Solution
A method involving a pre-coreflood, coreflood, and post-coreflood process is employed, utilizing nuclear magnetic resonance (NMR) measurements, X-ray micro-computerized tomography (CT) scans, and SARA analysis to evaluate the performance of foam and gel treatments in heterogeneous core samples, including co-injection and alternate injection strategies to enhance oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foams and gels are used to increase injectant viscosity and reduce mobility, then sweep efficiency and conformance control are improved, but stability degradation occurs at reservoir conditions with time and distance
Solution Approach 1:
The treatment is divided into multiple sequential stages: gel injection first to provide initial conformance control and mobility reduction, followed by foam injection to enhance sweep efficiency. This segmentation allows each material to perform its optimal function while mitigating the stability limitations of individual treatments.
Solution Approach 2:
The patent combines gel and foam into a composite treatment system where gel provides viscosity modification and conformance control in high-permeability zones, while foam provides additional mobility reduction and sweep efficiency enhancement. The combination creates a synergistic effect that overcomes the stability degradation issues of single treatments.
2Reliability
If gel treatment is applied during gas injection for enhanced oil recovery, then conformance control is improved, but unfavorable viscosity or mobility ratio challenges arise
Solution Approach 1:
The patent dynamically adjusts treatment parameters including gel concentration, foam gas-to-liquid ratio, and injection rates to optimize the viscosity and mobility ratio at different stages of the EOR process. This allows maintaining favorable flow characteristics while achieving conformance control.
Solution Approach 2:
The sequential gel-foam injection provides continuous conformance control and mobility management throughout the gas injection process, ensuring sustained improved oil recovery performance without interruption or degradation of treatment effectiveness.
3Productivity
If gravity override occurs due to density contrast between injectants and reservoir fluids, then miscible displacement performance deteriorates, but conformance control becomes more difficult
Solution Approach 1:
The gel treatment is specifically targeted to high-permeability zones and thief areas where gravity override is most problematic, providing localized conformance control. The foam then provides broader mobility reduction to counteract gravity effects throughout the reservoir, addressing the density contrast issue at both local and global levels.
Data Source
AI summary
Described is a method for evaluating oil recovery. The method includes performing a pre-coreflood process, a coreflood process, and a post-coreflood process. The pre-coreflood process includes preparing heterogenous cores samples with different structural configurations. The coreflood process includes injecting a treatment into the core samples and obtaining nuclear magnetic resonance (NMR) measurements of the treated core samples. NMR measurements are compared to assess performance of the treatment. The post-coreflood process includes conducting an X-ray micro-computerized topography (CT) scan and a Saturate, Aromatic, Resin, and Asphaltene (SARA) analysis on the treated core samples.