多层透镜状致密砂岩气田井网优化技术对策

苏里格致密砂岩气田储层物性差、垂向上发育多层透镜状有效砂体、规模小、非均质性强，现有井网对储层控制不足，采收率偏低。井网优化调整是致密气提高储量动用程度及采收率的最有效手段之一。根据储层结构及气井生产开发效果，将气田可效益动用储层划分为3种类型，分别对应储量丰度为：>1.8×10⁸ m³/km²、（1.3~1.8）×10⁸ m³/km²、（1.0~1.3）×10⁸ m³/km²。基于不同储层条件下的密井网试验区实际生产数据，结合储层规模分析和气井泄气范围评价，兼顾开发效益和提高采收率，从采收率增幅拐点、区块整体有效、新井能够自保等方面开展适宜井网密度综合分析，明确了3类储层的适宜井网密度分别为3口/km²、4口/km²、4口/km²。苏里格致密砂岩气田剩余可动储量1.23×10¹² m³，新的差异化布井方式相比于600 m×800 m井网，可多钻井1.2万口，多建产能450×10⁸ m³，累计多产气2 000×10⁸ m³，可将采收率由32%提升至48.5%。

Technical countermeasure of well pattern optimization in multi-layer lenticular tight sandstone gas field

Sulige tight sandstone gas field is characterized by poor reservoir physical properties, multi-layer lenticular reservoir structure, small scaled sand bodies and strong heterogeneity. That the existing well pattern has insufficient reservoir control results in low recovery factor. At present, the well pattern infilling adjustment is one of the most effective means to enhance the recovery factor. According to reservoir structure and gas well production effect, the recoverable reservoirs of the gas field can be divided into three types, corresponding to the reserves abundance of>1.8×10⁸ m³/km²， （1.3-1.8）×10⁸ m³/km²，（1.0-1.3）×10⁸ m³/km². Based on the production data of dense well pattern test area under different reservoir conditions, combined with analysis of reservoir scale and scope of gas well deflating evaluation, combining development efficiency and recovery factor enhancement, the suitable well spacing density comprehensive analysis was carried out from the perspectives of inflection point of recovery factor enhancement, overall development effectiveness of the well groups, and the break-even point of the infilling well. It is determined that the suitable well pattern density for type I, II and III reservoirs is 3, 4, and 4 wells/km², respectively. The scale of remained producing reserves of the gas field is 1.23 trillion cubic meters. If new well pattern is deployed there, compared with the 600 m×800 m well pattern, 12 000 more wells can be drilled, additional 45 billion cubic meters producing capacity can be built, another 200 billion cubic meters of gas will be produced. Then, the recovery factor will rise from 32% to 48.5%.