苏里格气田有效储层解析与水平井长度优化

Analysis on effective reservoirs and length optimization of horizontal wells in the Sulige Gasfield

水平井凭借其独有的技术和经济优势,已成为高效开发致密气藏的关键技术,但是其在非层状气藏的开发中却效果较差。为此,针对鄂尔多斯盆地苏里格气田二叠系下石盒子组8段含气砂体孤立分散的分布特点,采用露头类比、地质统计、密井网先导试验3种方法研究了该气田含气砂体的展布方向及规模特征,结合密集井网区精细地质解剖成果,提出了4种适用于该气田盒8段部署水平井的含气砂体分布样式：①厚层块状孤立型;②具物性夹层的垂向叠置型;③具泥质夹层的垂向叠置型;④横向串糖葫芦型。统计当前已实施水平井钻遇含气砂体的情况,发现所钻遇的含气砂体长度多数分布在670~1300 m。以苏X区SuX-18-36典型井组的物性夹层垂向叠置型砂体为例,结合生产数据修正法、数值模拟法及经济评价法,优化了气田合理水平段长度,认为在当前经济技术条件下,1200 m以内的水平段长度适合于该气田的该类叠置样式的砂体。该成果为该气田的后续高效开发提供了技术支撑。

By virtue of unique technical and economical advantages, horizontal well development has become a key technology in the high-efficiency development of tight gas reservoirs, however, this has worked unsatisfactorily in unstratified gas reservoirs. In this paper, the orientation and coverage of gas-bearing sand bodies （in isolated distribution） of Member 8 of Permian Lower Shihezi Fm in the Sulige Gasfield were analyzed by means of outcrop analogy, geostatistical analysis and pilot tests of dense well patterns. Then, four gas-bearing sand distribution patterns suitable for the deployment of horizontal wells in Member 8 were proposed according to the precise geological anatomy results of dense well patterns. These patterns include thick massive isolated pattern, vertically superimposed pattern with phys- ical interlayers, vertically superimposed pattern with argillaceous interlayers and lateral sugar-coated haw string pattern. Based on the statistics on gas-bearing sand bodies drilled by horizontal well drilling, the drilled gas-bearing sand bodies are 670-1 300 m long. Based on production data correction, numerical simulation and economic evaluation, the length of rational horizontal sections were optimized by performing a case study of the vertically superimposed reservoirs with physical interlayers in the typical well group SuX-18-36 of Su-X Block. It is indicated that the rational horizontal well length within 1 200 m in the Sulige Gasfield under current economic and technical conditions. This paper provides a technical support for the high-efficiency development of the Sulige Gasfield in the future.