致密砂岩气藏剩余气开发潜力定量评价

Quantitative Evaluation for Development Potential of Remaining Gas in Tight Sandstone Gas Reservoirs

致密砂岩气藏剩余气分布规律复杂、开发潜力难以定量评价,制约了开发中后期的加密调整。针对剩余气定量表征存在的问题,以川西地区新场气田沙二气藏为例,综合数值模拟、已实施加密水平井开发效果及经济效益,确定了影响剩余气潜力的因素由大到小依次为地层压力、储量丰度和渗透率。为综合考虑上述各因素对剩余气区加密井经济可采储量的贡献,定义了剩余气潜力指数,并结合经济评价建立了剩余气潜力指数与加密水平井经济可采储量的数学表达式,实现了对剩余气开发潜力的定量化表征。实例分析表明,新场气田沙二气藏中剩余气开发潜力指数大于0.7的井区具有利用水平井加密的潜力。据此,在主力开发层系Js_(2)^(4)气层东北部筛选出剩余气潜力区1个,通过实施部署水平井实现了对边部高含水剩余气区储量的有效动用。部署的加密水平井效果良好,验证了所建立剩余气开发潜力定量评价方法的有效性。

The distribution of remaining gas in tight sandstone gas reservoir is complex,and it is difficult to quantitatively evaluate the development potential,which restricts the development and adjustment of gas reservoir at the middle and late stage.Aiming at problem of quantitative characterization of remaining gas,taking Js2 gas reservoir in Xinchang Gas Field as an example,comprehensive numerical simulation and actual encryption adjustment well development effect and economy,the factors affecting the remaining gas potential are formation pressure,reserve abundance and permeability in descending order.The remaining gas potential index is defined to comprehensively consider the contribution of the above factors to the economically recoverable reserves of infill wells in the remaining gas areas.Then,the mathematical expression which can be used to describing the relationship between remaining gas potential index and economic recoverable reserves of infilled horizontal wells is established.So,the quantitative characterization of the development potential for remaining gas is realized.For Js2 gas reservoir in Xinchang Gas Field,case analysis shows that horizontal wells can be used to infill the areas if the remaining gas development potential index of is greater than 0.7.Accordingly,one favorable area is selected in the northeast of Js_(2)^(4) gas layer,and the reserve of the remaining gas area with high water cut in the edge is effectively utilized by infilling a horizontal well.The quantitative evaluation method for remaining gas is verified by the production of the infilling horizontalwell.