苏里格气田南区上古生界气井低产原因分析

Analysis of reasons of low yield from Upper Paleozoic gas wells in Southern District of Sulige gasfield

苏里格气田南区上、下古生界复合含气，是下一步长庆天然气产能建设的重要接替区。该区上古生界主力含气层段为二叠系石盒子组盒8段和山西组山1段，各含气层段在储层特征上与苏里格气田其他区块存在一定差异。近年来勘探、开发成果证实该区具有较好的开发潜力，但区内上古生界投产井生产动态特征资料显示。气井总体产量较低，稳产能力较差。目前上古生界投产气井140口，日均开井91口，日产气量为50．5×10^4m^3．平均单井产气0．55×10^4m^3/d，平均套压11．2MPa。针对这一生产现状，主要从沉积、成岩角度，深入剖析了研究区上古生界气藏低产、低效的原因，认为在大的沉积背景下，研究区位于三角洲前缘，距离物源远，砂岩埋藏深且粒度细，单砂体段多层薄，软性组分含量较高，压实作用及胶结作用强烈，导致储层物性变差等都是导致研究区上古生界低产的主要因素。另外．区内井上古生界普遍产水，水气比比较大，对气井产量影响亦较大。

The Upper and Lower Paleozoic in Southern District of Sulige gasfield are compositely gas-bearing. Reservoir characteristics of each gas-bearing interval are different from that of other blocks in Sulige gasfield. The verall production rate of the gas well is low, with less stable production capacity. For this production status, proceeding mainly from deposition and diagenetic aspects, in-depth analysis of the low-yiehl and inefficient reasons of the Upper Paleozoic gas reservoirs in the study area is conducted in this article. It is considered that, in a large sedimentary background, the study area is located in the delta front, far from the source material. The sandstone is fine-grained and deep buried. The single sand body interval has multiple thin layers, with high soft-component content, intense compaction and cementation, leading to poor reservoir properties. These are main factors that cause the low-yield of the Upper Paleozoic reservoirs in the study area. In addition, the gas wells in the region generally produce water from the Upper Paleozoic, with relatively large water-gas ratio, and a large impact on the gas well production.