苏里格气田致密气藏水平井指标分类评价及思考

致密砂岩气藏是我国天然气资源的重要类型，水平井是提高该类气藏单井产量的主要技术手段。鄂尔多斯盆地苏里格气田致密气藏砂体的内部结构复杂，气层薄而分散，具有很强的非均质性，水平井产能差异极大。因此，采用气井分类评价的思路，建立不同类型气井地质模型与产能动态特征关系，按产能和经济效益将气井分为好、中、差３类。根据目前该气田水平井的部署情况，分类评价水平井优选井位加密部署和区块整体部署两种方式下水平井的开发指标，用以指导致密气藏水平井的开发评价。在此基础上，针对致密气藏产能评价的难点，提出了基于单裂缝的水平井产能评价新思路；从致密砂岩气藏提高储量动用程度的角度，初步讨论了水平井砂体内部构型、开发后期剩余储量的分布方式，并给出了相应的开发建议：非主力层未动用储量采用混合井型井网进行开发，主力层段内的未控制储量要在经济技术允许的条件下；水平井井距和压裂间距应按照合理范围的下限来考虑。

Classification and evaluation of horizontal well performance in Sulige tight gas reservoirs, Ordos Basin

Tight sandstone gas reservoirs provide another important type of natural gas resources in China, and the horizontal well is a major technical means to improve the single well production of this type of gas reservoirs. Sulige tight gas reservoirs are characterized by complex internal structures of sand bodies, and thin and dispersed gas layers with strong heterogeneity, thus the productivity of horizontal wells varies greatly there. Therefore, the idea of classified evaluation was adopted for the gas wells in this field. The relationships between geologic models and production performance characteristics were then established in accordance with different gas wells; based on the productivity and economic benefit, the gas wells there are classified into 3 types: excellent, moderate and poor. According to the current deployment of horizontal wells in this field, the classified evaluation was conducted for the development indexes under 2 modes, i.e., the infilling deployment and integrated block deployment for optimizing positions of horizontal wells, providing guidance for developing and evaluating horizontal wells of tight gas reservoirs. On this basis, a new productivity evaluation idea was proposed for horizontal wells with single fracture to solve the difficulties in the productivity evaluation for tight gas reservoirs. From the perspective of increasing the producing degree of reserves in tight sandstone gas reservoirs, the issues were discussed preliminarily including the internal structures of sand bodies in horizontal wells and the distribution modes of the residual reserves in the later development stage. As a result, appropriate development proposals were presented: for the non producing reserves in non main pay zones, the well grid with mixed well types should be adopted; but for the non controlled reserves in major pay zones, on the premise that the economic and technical conditions are allowable, the well spacing and fractured space should be both controlled at the lower limits of reasonable ranges.