苏里格大型致密砂岩气田储层结构与水平井提高采收率对策
Reservoir Distribution in the Sulige Large Tight Sandstone Gas Field and Methods for Enhancing Recovery Efficiency of Horizontal Wells

摘要： 在分析苏里格气田辫状河体系及储层结构特征的基础上，提出了剖面储量集中度的概念，建立了厚层块状型、垂向叠置泛连通型、分散局部连通型、分散孤立型4种砂体分布模式，探讨了不同储层结构下的水平井采出程度，提出了水平井提高采收率技术对策。研究结果表明，辫状河沉积体系复合有效砂体由于“阻流带”的存在，直井动用不完善，水平井能克服“阻流带”的影响，提高层内储量动用程度；但由于砂体多层状分散分布，水平井开发会导致纵向含气层系储量动用不充分，影响层间采出程度。对于剖面储量集中度高的厚层块状型、垂向叠置泛连通型储层，采用水平井整体开发，Ⅰ+Ⅱ类井比例达70%以上，可显著提高储量动用程度和采收率。对于剖面储量集中度低的分散局部连通型储层，采用直井井网开发后进行甜点式优选水平井井位加密部署，可提高采收率10%以上。
Abstract: Based on the braided river system analysis and reservoir distribution characteristics of the Sulige large tight sandstone gas field, the concept of reserves concentration is proposed and four sandbody distribution models are established, namely the thick block, vertical overlapping panconnected, dispersed partiallyconnected, and dispersed types. Reservoir recovery of horizontal wells under different sandbody combination is analyzed, and technical measures to improve the recovery rate of horizontal wells are proposed. The results show that straight wells is imperfect due to the blocking zones present in compound sand body of the braided river sedimentary system.Horizontal well can overcome the blocking zone influence and increase the degree of reserve exploitation within the layer.However, the scattered distribution of layered sand bodies and the horizontal well development will lead to insufficient vertical bearing department of gas reserves, and thereby reducing the degree of interlayer recovery. For the greater reserves concentration, thick block and multivertical overlapping panconnected types and horizontal well development can significantly improve the degree of reserve exploitation and recovery, of which over 70% are Ⅰ+Ⅱ wells. For the disperse partially connected reservoirs with lower reserve concentration, development of vertical well pattern and optimization of the horizontal well distributions can improve the recovery by more than 10%