苏S区块低渗气藏气井产量递减规律

Study on the Decline Rules of Gas Wells in Low Permeability Gas Reservoir in Su S Block

苏里格气田苏S区块属于典型的“三低”气藏,储层致密,气井一般要进行人工压裂才能投产,同时气藏采用衰竭开发模式,主要采气期和产气量集中于递减期,因此对气井产量递减问题的研究具有重要意义和实际应用价值。本文针对低渗气藏的地质情况及气井的渗流特征,采用传统与现代产量递减分析相结合的方法,从单井入手,对不同类型井的产量递减规律进行研究,并计算地层系数、裂缝半长、表皮系数、泄气半径和动储量等参数。研究表明:Ⅰ类井属于指数递减,平均年递减率为19.44%;Ⅱ、Ⅲ类井符合双曲递减规律,Ⅱ类井平均年递减率为15.34%,Ⅲ类井平均年递减率为14.51%;依据递减公式,研究区已投产井的有效开采时间为8~15a。

Su S block of Sulige gas field is a typical “three low” gas reservoir with compact reservoir. Gas wells usually need artificial fracturing to put into production. Simultaneously, the depletion development mode is adopted, and the main production period and gas production are concentrated in the decline period. Therefore, the research on the decline of gas well production is of great significance and practical application value. In view of the geological conditions of low permeability gas reservoirs and the influent characteristics of gas wells, this paper studied the production decline law of different types of wells by combining traditional and modern production decline analysis, and calculated the formation coefficient, fracture half-length, skin factor, gas release radius and dynamic reserves. The results show that type Ⅰ wells belong to exponential decline, with an average annual decline rate of 19.44%. Type Ⅱ and Ⅲ wells conform to hyperbolic decline law, and type Ⅱ wells have an average annual decline rate of 15.34%. Type Ⅲ wells have an average annual decline rate of 14.51%. According to the decline formula, the effective production time of production wells in the study area is 8~15 a.