Study on the Countermeasures and Mechanism of Balanced Utilization in Multilayer Reservoirs at Ultra-High Water Cut Period

Abstract

After entering the ultra-high water cut stage of multilayer oil reservoirs, the remaining oil is highly dispersed. Due to the continuous development of general water injection, the generation of advantageous channels makes interlayer contradictions more prominent, and the differences in the utilization between different layers are even greater. After the water drive development of multilayer oil reservoirs enters the ultra-high water cut stage, the development effect deteriorates year by year. Layer restructuring is an effective method of improving the water injection development effect and increasing the degree of utilization. In essence, its goal is to achieve balanced utilization for multiple development layers to increase the degree of recovery. This article mainly employs physical simulation experiments combined with reservoir numerical simulation technology to jointly study the effects of different equilibrium production strategies in the ultra-high water cut period of multilayer oil reservoirs and their mechanism of action based on the remaining oil distribution field and streamline field. As a specific implementation, we use large-plate physical simulation to demonstrate the effectiveness of the rotational injection and production strategy, and to supplement the physical simulation experiment with a reservoir numerical simulation model, we analyze the mechanism of different balanced production strategies. The research results for the combination of physical simulation experiments and numerical simulation experiments show that the combined strategy of rotary injection and rotary production is the most effective method for use in multilayer and ultra-high water cut oil reservoirs. The displacement effect of the high-permeability layer is better, and the increase in the recovery degree is relatively large, while the displacement effect of the low-permeability layer is relatively weak. After conventional water drive oil recovery, the remaining oil mainly exists in the edge area of the research area. However, the use of three-dimensional well network injection wheel recovery changes the streamline field, produces the effect of fluid flow diversion, expands the water drive sweep coefficient, and improves the recovery rate. Chemical plugging can effectively replace water drive oil recovery and will become the main method for improving the recovery rate of such reservoirs in the lower part.

Optimization Algorithm and Genetic Coding Method for an Oilfield Development Plan Considering Production Constraints

“…Starting from a set of randomly generated solutions, dominant individuals are selected in the iterative process, and the individual dominant genes are transmitted to the next set of solutions through genetic operations. The genetic process is repeated until the solution that meets the correct conditions is obtained [20][21][22][23]. Unlike other traditional methods, genetic algorithms do not search from a single point; rather, they search from multiple points.…”

Research on Water Invasion Law and Control Measures for Ultradeep, Fractured, and Low-Porosity Sandstone Gas Reservoirs: A Case Study of Kelasu Gas Reservoirs in Tarim Basin

“…In order to put forward effective control measures and means, on the basis of studying the geological characteristics of the gas reservoirs, combined with gas reservoir production performance, using embedded discrete fracture model numerical simulation (EDFM), among other means, a water invasion model of ultradeep, fractured, and tight gas reservoirs is established, considering the two factors of the fault and fracture development degrees [13,14]. It is applied to the Keshen gas reservoirs in the Kuqa Depression to study the phase mechanism.…”

“…It is applied to the Keshen gas reservoirs in the Kuqa Depression to study the phase mechanism. The EDFM and actual gas reservoir production performance are used to verify the effectiveness of the water invasion model [14][15][16][17]. Water invasion control measures for this kind of gas reservoir are put forward to improve the overall recovery rate of gas reservoirs.…”

Mechanism of Pressure Difference Variations on Heavy Oil Start-Up and Percolation Effects

“…The stable and efficient percolation of heavy oil after initiation is the key to maintaining and increasing production during the later stages of heavy oil field development. Regarding development plans, the well network can be enhanced by considering the distribution of remaining oil, which can help adjust the distribution and improve flow efficiency . As for development technology, microbial system oil recovery primarily reduces crude oil viscosity and oil–water interfacial tension by altering the properties of crude oil through metabolic products that lead to efficient percolation .…”

“…Regarding development plans, the well network can be enhanced by considering the distribution of remaining oil, which can help adjust the distribution and improve flow efficiency. 14 As for development technology, microbial system oil recovery primarily reduces crude oil viscosity and oil–water interfacial tension by altering the properties of crude oil through metabolic products that lead to efficient percolation. 15 The hot fluid system for oil recovery mainly improves the flow efficiency by heating crude oil, reducing its viscosity, dissolving and expanding it, and also maintaining formation pressure.…”