Liu Huiqing

The Investigation of Threshold Pressure Gradient of Foam Flooding in Porous Media

Abstract Porous media were simplified as a series of constricted capillary tubes related to particle size and arrangement, and the distribution of pore diameter and pore volume factor in the pore cell was calculated. Based on mechanics theory, the models of threshold pressure gradient (TPG) for a pore cell and porous media were obtained that provided a comprehensive consideration of pore structure, gas–liquid ratio (GLR), gas–liquid interfacial tension, and the deformation characteristics of bubbles in throat and pore. Moreover, the experiments on the TPG of foams at steady state were investigated. The results showed that the TPG decreases sharply as the particle size increases up to 400 μm and then decreases slightly. The greater the interfacial tension, the higher the TPG, and there exists a approximate linear correlation between them. In addition when the GLR is lower than 20:1, the TPG increases rapidly as the GLR increases, and then the TPG remains almost steady.

A New Technology for the Exploration of Shale Gas Reservoirs

Abstract Energy consumption in the world increases 5.6% every year, and alternative resources like shale gas, coal-bed methane (CBM), tar sand, and so on are strongly needed. Shale gas is an unconventional natural gas of enormous potential. Abundant shale gas resides in the form of adsorption gas. Desorption of shale gas is an important mechanism and power source of shale gas reservoir development. Based on the features of shale gas reservoirs, the adsorption/desorption mechanisms, and their influencing factors, high-temperature mixture gas flooding is proposed in this article. Combining the theories of surface chemistry, chemical thermodynamics, and physical chemistry, this article investigates the mechanisms of developing shale gas reservoirs by high-temperature mixture gas flooding, which are illustrated in the following aspects: (1) increasing temperature to accelerate desorption; (2) competitive adsorption, lowering partial pressure of CH4, and accelerating diffusion; (3) increasing moisture on the shale surface; (4) decreasing total organic content (TOC) and improving permeability; and (5) providing displacement energy.

Experimental Study of Non-Darcy Two-Phase Flow in a Fractured – Vuggy Medium

In order to study the characteristics of the flow regime, we conducted experiments on filtration of pure water and water/oil through an artificial fractured – vuggy medium. We found that both Darcy and non-Darcy flow can occur in a fractured – vuggy medium. After rewriting the Forchheimer equation, we calculated the inertial coefficient for different fracture widths and vug diameters. Based on the experimental studies, we also propose a new method for determining the flow regime for twophase flow using fractal theory.

Interpretation of temperature profiles during soak periods in steam-stimulated wells

To address the problems existing in testing steam injection profiles in a steam-stimulated well during steam injection and production periods, this paper proposes that the temperature profile in the completion interval could be tested during the soak period. A mathematical model for calculating the vertical distribution of temperature in a single layer reservoir is established based on the temperature characteristics of steam stimulated reservoirs, and the vertical distribution of temperature in a single layer reservoir could be obtained and heat loss could be calculated. The temperature, which is disturbed by thermal conduction in a multilayer reservoir, and heat loss could be derived based on the superposition principle of temperature potential. This paper establishes a multilayer testing temperature profile interpretation method and interprets the actual test temperature profile of Well Gao 3-7-66. The results indicate that the temperature profile in the soak period can reflect the thermal absorption conditions in various reservoir beds.

Steam flooding after steam soak in heavy oil reservoirs through extended-reach horizontal wells

This paper presents a new development scheme of simultaneous injection and production in a single horizontal well drilled for developing small block reservoirs or offshore reservoirs. It is possible to set special packers within the long completion horizontal interval to establish an injection zone and a production zone. This method can also be used in steam flooding after steam soak through a horizontal well. Simulation results showed that it was desirable to start steam flooding after six steam soaking cycles and at this time the oil/steam ratio was 0.25 and oil recovery efficiency was 23.48%. Steam flooding performance was affected by separation interval and steam injection rate. Reservoir numerical simulation indicated that maximum oil recovery would be achieved at a separation section of 40–50 m at steam injection rate of 100–180 t/d; and the larger the steam injection rate, the greater the water cut and pressure difference between injection zone and production zone. A steam injection rate of 120 t/d was suitable for steam flooding under practical injection-production conditions. All the results could be useful for the guidance of steam flooding projects.