Composite Decline Rate Calculation Method Research of the Scrolling Development Gas Field

Abstract

Composite decline rate is an important factor controlling gasfield production and development plans. Production decline analysis has been focused on individual wells, especially on oilfield development, but less studies on the composite decline rate in gasfield. In this study, by collecting gasfield data involving productivity and production decline rate and analyzing the physical significances, the numerical relationship between productivity and production decline rate is proposed based on the Arps decline theory. At present, natural gas development depends on low-permeability gas reservoirs, gas wells have no stable production, and gas production must be kept stable by increasing gas wells, so it is proposed to classify gas wells by the year when they were put into production, and analyze their productivity and production decline. The composite decline rate can be calculated by weighting the gas production in various years. This method has two distinct advantages. On the one hand, it avoids data dispersion in clustering analysis due to individual wells by taking yearly brought-in wells as an analyzing unit. On the other hand, it solves the contradiction between stable production and production decline. Case analysis indicates that the calculation of composite decline rate with yearly production of brought-in wells can not only complete decline rate analysis by increasing wells, but also provide certain significance for gasfield production planning and new well deployment.