致密砂岩气藏井网加密潜力快速评价方法

Quick evaluation methodology of infill drilling potential in tight sandstone gas reservoirs

致密砂岩气藏地质条件复杂,采收率较低,国内外开发实践表明井网加密已成为此类气田提高采收率的关键技术。针对致密砂岩气藏开发井数多、快速评价井网加密潜力数值模拟方法不经济、地质统计法和移动窗口法评价结果与实际差异较大等问题,综合地质研究与气井动态资料,采用不稳定流动分析方法,建立井网密度与单井增加可采储量的关系。从加密井单井增加可采储量出发,结合经济学原理,建立了加密效益函数,能够快速准、确预测出开发区是否具有加密潜力及加密潜力大小,为气田调整挖潜决策提供可靠依据。实例应用结果表明,大牛地气田DK13井区山西组1段天然气在目前成本和价格下,经济最佳井网密度为2.2口/km2,经济极限井网密度为7.06口/km2,加密潜力较大。

Recovery factor of tight sandstone gas reservoir is low due to disadvantageous geological condition. Domestic and overseas development practices indicate the importance of infill drilling for EOR. Several methods including numeri- cal simulation, geostatistical analysis and moving split-window are available for rapid evaluation of in-fill drilling poten- tial. However,the numerical simulation method is high in cost, and the geostatistical analysis and moving split-window methods are not accurate. In this paper, a functional relationship is established between well spacing density and incre- mental recoverable reserve of single well based on geological data and dynamic behavior analysis. The infill drilling profit function is developed based on economic principles. The proposed quick evaluation method can be used to evaluate the potential of infill drilling and support decision making in development adjustment and potential tapping of tight gas reser- voirs. Case study result shows great infill drilling potential in DK13 Block in Daniudi gas field, the optimal economic well spacing density is 2. 2 wells/km2, the economic limit well spacing density is about 7.06 wells/kin2 under current oil price and operation cost.