A Novel Dynamic Splitting Method for Production Based on Material Balance Theory and Catastrophe Theory in Tight Gas Reservoirs

Shengye Hao,Pengcheng Liu,Xinyu Qiu,Xiaoxia Chen

doi:10.1155/2021/9950011

Abstract

Splitting methods play a significant role in the coproduction of tight reservoirs which are characterized by vertical multilayer superimposition. It directly affects the accuracy of reservoir performance analysis and detailed descriptions. However, conventional splitting methods are limited to a few factors and static factors without considering the effect of layer parameter change. In this study, sensitivity analysis was carried out on five factors that affect the production splitting in coproduction wells. The research shows that in the production process, multiple parameters have a direct impact on the production of layers. Different parameters, which have to be included to split production, have different scale effects on layer production. Comparing the results of the KH method with the numerical simulation results, the limitation of the KH method for yield splitting is illustrated. A novel dynamic splitting method for production (DPSM) was proposed. This method is based on two primary methods, which are the multifactor static method for production splitting of gas (GPSM) and water (WPSM) and use the catastrophe theory and material balance equation (MBE) and obtain the final results by iterative method. The advantage of this method is that more accurate results in the production process are obtained by selecting eight factors, which contain 6 static factors and 2 dynamic factors, for research. It is more in line with the production practice that the ultimate results of production splitting vary with the production process. The accuracy and practicality of the results had been verified by numerical simulation. This method has practical significance for production splitting in tight gas reservoirs.

Highlights

Tight gas reservoirs are the main targets of unconventional development [1,2,3]
The tight gas reservoirs, which are characterized by vertical multilayer superimposition, are often developed by the multilayer coproduction technology [6, 7]
A novel and more accurate dynamic splitting method considering dynamic and static factors was proposed based on catastrophe theory, material balance equation (MBE), and iterative calculation

Summary

Introduction

Tight gas reservoirs are the main targets of unconventional development [1,2,3]. China has shown great enthusiasm for developing tight gas reservoirs [4, 5]. Many scholars have modified this method: the KNK method considers well-controlled geological reserves (N) in layers [11], the KHKr method considering effective permeability (Kr) [12,13,14,15], and the production splitting method combining the KH method with the production profile testing method [16] These methods improve the accuracy of the Geofluids method at different levels, but it still cannot meet the practical application of gas reservoirs due to their only consideration of single factors and static factors. The calculation results of the fractional flow equation were limited to the parameters around the well and cannot accurately describe the dynamic changes of the entire reservoir. A novel and more accurate dynamic splitting method considering dynamic and static factors was proposed based on catastrophe theory, MBE, and iterative calculation. It is proved that DPSM is more accurate and more practical for tight gas reservoir by comparing with the KH method and original splitting method based on the catastrophe theory

Theoretical Method

Production Splitting Method Based on the Catastrophe Theory

Results and Discussion

Conclusion