复杂气藏开发早期计算动态储量方法及其适用性分析

A method for early-stage dynamic reserves calculation and its applicability in complex gas reservoirs

对储集类型、气水关系、连通性复杂的气藏,在开发早期要准确计算其动态储量较为困难,实际资料状况与计算方法所要求的条件之间存在难于避免的差距,在采出程度较低时常导致储量计算结果出现较大偏差。为此,重点分析了复杂气藏动态储量计算误差与地层压力数据的准确性、采出程度的敏感关系,以及不同方法计算结果差异原因和由此反映出的气藏储量动用特征,并对比分析了不同方法的适用条件。从提高压力计算准确性、优选计算方法、认识不同方法计算结果矛盾性的角度出发,探讨了在气藏开发早期提高动态储量计算准确性的技术途径,最后以四川盆地龙岗气田边部低渗透区的气井为实例有针对性地进行了储量评价,为制定开发对策提供了重要的技术依据。

For the gas reservoirs with great complexity in types,water-gas contact and connectivity,it is difficult to accurately estimate their dynamic reserves at the early stage,because there are inevitable deviations between the practical data and the conditions required by the calculation methods.As a result,the calculation results show a big difference from the actual data especially when the degree of reserve recovery is low.In view of this,this study focuses on analyzing the relationship between the calculation error of dynamic reserves and the reliability of formation pressure as well as the influencing factors of recovery degree.In addition,it analyzes the reasons for great difference in calculation results by different methods as well as the reflected dynamic characteristics of the produced gas reserves.Based on the above,comparisons and analysis are carried out about the applicable conditions for the different calculation methods.From the perspectives of how to improve the reliability of pressure,how to optimize the computational method,and how to recognize the results,the technical methods are investigated for increasing the calculation accuracy of dynamic reserves at the early stage.Accordingly,a case study is carried out for the reserve estimate of the gas wells in the low permeability zone of the Longgang Gas Field.This study provides technical support for the decision-makers to formulate their development strategies.