川西侏罗系致密砂岩气藏稳产关键技术与展望

川西侏罗系致密砂岩气藏类型复杂，河道砂叠置复杂，砂体展布不稳定，储量品质低，气水关系复杂。单井自然产能低、稳产能力差、可采储量低，气藏动用程度低、采收率低。为实现气藏持续上产、稳产，以地震老资料重处理与解释为基础，建立了完整的地球物理及测井精细评价技术体系，实现了河道砂岩精细刻画、储层精准预测及含水饱和度的定量评价。以“少井高产”为目标，依托地质工程一体化对难动用储量优选地质及工程双甜点，形成了平面上“一”字形、“Y”形、“X”形、“V”形等多形式组合，纵向上多层位、多井型井组优化的“一场多井、一井多层”混合井网+大规模多段多簇体积压裂储层改造工艺技术体系，施工排量从5$\sim$8 m$^3$/min提高到16$\sim$18 m$^3$/min，加砂强度由0.4$\sim$0.7 t/m提高到4.0$\sim$4.5 t/m，裂缝数量由20$\sim$30簇提高至50$\sim$80簇，单井产能从5.07$\times$10$^4$m$^3$/d提高到15.64$\times$10$^4$m$^3$/d。以地震—地质—建模—数模—工程—经济一体化为手段，摸清剩余气成因及规模，提出加密调整、转层、侧钻、重复改造及工艺维护等措施，提高气藏采收率，实现川西侏罗系致密砂岩气藏20$\times$10$^8$m$^3$以上持续稳产18 a。这些技术的推广应用，“十四五”期间西南油气分公司致密天然气年产量有望保持30$\times$10$^8$m$^3$以上并持续稳产。

Key Technologies and Prospects of Stable Production of Jurassic Tight Sandstone Gas Reservoirs in Western Sichuan

The characters of tight sandstone gas reservoir types in the Western Sichuan Depression were complex, such as complicated channel sand stacking, unstable the sand body distribution, low reserve taste, complex gas-water relationship, low natural productivity, poor stable production capacity, and low recoverable reserves in a single well. In order to achieve continuous production increase and stable production of gas reservoirs, based on the reprocessing and interpretation of old seismic data, a complete geophysical and logging fine evaluation technology system was established, which achieved fine characterization of channel sandstone, accurate reservoir prediction and water saturation and quantitative evaluation. Aiming to increase production, we selected double geological and engineering sweet spots and formed a mixed well pattern plus large-scale multi-stage and multi-cluster volume fracturing reservoir stimulation technology system, of which the type was the combination of linear, "Y" "X" "V" etc on the plane, and "multiple wells in one field and multiple layers in one well" with well type group optimization in vertical direction. The construction displacement was increased from 5$\sim$8 m$^3$/min to 16$\sim$18 m$^3$/min, and the sand addition intensity was increased from 0.4$\sim$0.7 t/m to 4.0$\sim$4.5 t/m, the number of fractures increased from 20$\sim$30 clusters to 50$\sim$80 clusters, and the single-well productivity increased from 5.07$\times$10$^4$ m$^3$/d to 15.64$\times$10$^4$ m$^3$/d. Taking seismic-eology-modeling-mathematical modeling-engineering-economic integration as means, the origin and scale of remaining gas were found out, and measures such as infill adjustment, layer transfer, sidetracking, repeated reconstruction and process maintenance were put forward to improve the gas reservoir recovery rate. It has achieved continuous and stable production of more than 2 billion cubic meters of tight sandston gas reservoirs in western Sichuan for 18 years. With the popularization and application of these technologies, the Southwest Oil and Gas Company$'$s annual production of tight natural gas is expected to remain above 3 billion cubic meters during the "14th Five-Year Plan" period, and the production will continue to be stable.