Monitoring of Flooding Characteristics with Different Methane Gas Injection Methods in Low-Permeability Heterogeneous Cores

Abstract

Methane gas injected into reservoirs can greatly enhance oil recovery and has been widely used. However, continuous methane gas flooding has a deleterious effect on oil recovery enhancement and easily causes gas channeling in low-permeability heterogeneous reservoirs because of the low viscosity and high mobility of methane gas. This study consists of comprehensive experimental research that combines physical simulation and saturation dynamic monitoring technologies with a component analysis of produced oil to investigate the oil recovery and mobility control effects in lowpermeability heterogeneous cores. First, solubility, foaming ability, and stability are used as evaluation indicators. The results show that an alcohol ethoxylate foaming agent at 1.5 wt % is suitable for reservoirs, based on the Waring blender and Ross−Miles methods combined with microscopic observation. Second, methods of methane gas with water alternating gas (WAG) injection, advanced cyclic water alternating gas (ACWAG) injection, and methane nonionic foam injection are performed on three kinds of low-permeability heterogeneous cores under reservoir conditions. The experimental results show that methane nonionic foam flooding can significantly improve oil recovery by 11−18%. Third, the residual oil saturation in the core is tested by saturation dynamic monitoring. This finding indicates that methane nonionic foam flooding reduces mobility control, effectively restrains gas channeling, increases sweep efficiency, and has the highest permeability plugging rate (82−90%) for high-permeability channels. In the stage of methane WAG and ACWAG flooding, methane gas can increase the C 12 −C 24 components in the produced oil by 0.3−0.9%. ACWAG injection can improve the stage of no watercut oil recovery compared with conventional WAG injection.

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

“…After long-term water flooding, oil reservoirs formed a number of water channels. These channels led to fluid fingering and seriously affect the stable production of the reservoir for water or CO 2 flooding . The general types of channels include fractures formed by fracturing, natural fractures, and some other high permeability channels .…”

“…These channels led to fluid fingering and seriously affect the stable production of the reservoir for water or CO 2 flooding. 60 The general types of channels include fractures formed by fracturing, natural fractures, and some other high permeability channels. 61 For CO 2 flooding, these are also the main channels for gas migration.…”

Review on Oil Displacement Technologies of Enhanced Oil Recovery: State-of-the-Art and Outlook

“…After much literature research and laboratory investigation, a variety of existing experimental devices are divided into four categories in this review, i.e., oil displacement device with microscopic visualization, − oil displacement device using sand-filling tube test, ,,− core displacement test device, ,,− oil displacement device using glass beads, ,,− and 3D multifield coupling experimental system. − …”

Application of 3D Embedded Discrete Fracture Model for Simulating CO2-EOR and Geological Storage in Fractured Reservoirs

“…Although CO 2 injection into conventional high-permeability reservoirs has been used for many years to enhance oil recovery, the studies of CO 2 -EOR and geological sequestration in low-permeability reservoirs are still quite inadequate, especially in complex fault-block reservoirs, which cannot form the regular well pattern [14]. Low-permeability reservoir refers to reservoirs with low porosity, poor fluid seepage capacity, and low natural productivity, which are difficult to develop on a large scale by conventional production approaches [15,16]. Low permeability is a relative concept.…”