Experimental and Numerical Simulation Analysis of Factors Affecting CO₂ Geological Storage and Enhanced Oil Recovery in Extra-Low Permeability

Abstract

Carbon neutrality has become the long-term development strategy of many countries worldwide, and the widespread implementation of CCUS (carbon capture, utilization, and storage) is critical for achieving this goal. Ultralow permeability reservoirs have good storage and shielding properties, making them ideal for CO2 geological storage. CO2 into these reservoirs has the dual purpose of improving crude oil recovery and protecting the environment. However, the physical properties of ultralow permeability reservoirs are poor. Furthermore, the distribution of fractures is often complex. The mechanism and influencing factors of the CO2 storage are still unclear. Here, the CO2 storage in ultralow permeability reservoirs is analyzed through core displacement experiments and numerical simulation. The main influencing factors of cumulative oil production and CO2 storage capacity were calculated through gray correlation theory, including CO2 injection rate, permeability, porosity, the solubility of CO2 in water, and the bottom hole flow pressure of production wells. The research results show that the geological storage of CO2 in ultralow permeability reservoirs mainly consists of structural trapping and dissolution into the residual fluids; in the short term, mineralization is relatively small and can be ignored. Within the 15 years predicted by numerical simulation, the injected CO2 into the Y28–102 well group in the Huang3 district was structurally trapped, with a total capacity of 6.59 × 104t. The burial ratio was 63.4%, of which structural burial accounted for 82%, oil dissolution accounted for 9%, water dissolution accounted for 8%, and mineral burial accounted for approximately 1%. The research results reference CO2 flooding and geological storage in ultralow permeability reservoirs.

Innovative Zoning Control Techniques for Optimizing a Megaton-Scale CCUS-EOR Project with Large-Pore-Volume CO2 Flooding

“…The HX block has been put into operation since 2006, using a diamond-shaped reverse nine-point well network for synchronous water injection development . Due to poor reservoir properties, it is difficult to inject water and establish an effective displacement system.…”

“…The permeability of high permeability channels in Class I is mainly distributed between 15 and 50 mD, while Class II is above 50 mD. The fluid model was based on existing oil composition, single degassing test data, and constant composition expansion experiment data. , Then, use WinProp for PVT matching. Firstly, 9 components of the pseudo component model were identified as shown in Table , and the parameters related to oil properties were fitted and corrected.…”

“…49 The HX block has been put into operation since 2006, using a diamond-shaped reverse nine-point well network for synchronous water injection development. 50 Due to poor reservoir properties, it is difficult to inject water and establish an effective displacement system. As shown in Figure 2, the reservoir pressure maintains a relatively low level, with only 69% pressure maintained in 2016, resulting in an uneven distribution of planar pressure.…”

“…The permeability of high permeability channels in Class I is mainly distributed between 15 and 50 mD, while Class II is above 50 mD. The fluid model was based on existing oil composition, single degassing test data, and constant composition expansion experiment data 50,59.…”

Data-Driven Quantitative Study of Synergistic Effects on CCUS-EOR─A Case Study of Ultralow-Permeability Sandstone Reservoirs

“…This is because ultralow-permeability reservoirs, with their low porosity and permeability characteristics, are suitable for CO 2 flooding. Additionally, these reservoirs have dense cap rocks, providing a certain level of sealing, making them suitable for the long-term storage of CO 2 . − …”