通过对威远地区14口评价井或导眼井五峰组—龙马溪组地层开展系统的笔石生物地层、岩相地层、测井响应、地球化学、元素地球化学等特征分析,证实了威远地区五峰组—龙马溪组古隆起的发育,指出古隆起发育控制页岩的厚度及岩相展布,明确优质页岩展布受古隆起发育控制,并提出水平井井位优化部署建议.主要结论如下:1)从生物地层、岩性地层、电性特征、地层厚度等方面证实在Z4-Z1—WY1—W5—WX井一带存在(水下)古隆起;2)不同时期地层分布及岩相主要受古隆起发育控制,隆起区及周边地层厚度薄,黏土矿物或碳酸盐矿物含量高,坳陷区沉积厚度大,硅质矿物含量高;3)威远地区五峰组页岩沉积期物源多来自其西部或北部,鲁丹阶早期以生物成因石英为主,物源较少,鲁丹阶晚期物源可能来自川南的黔中古陆,不同的物源方向意味着沉积体系的变化;4)鲁丹阶早期(LM1～LM3)地层储层品质最优,产量高,其储层参数平面展布受隆起发育控制,拗陷区域储层品质最好.建议以鲁丹阶早期地层为目标靶体实施水平井,优先部署该层段厚度较大区域水平井,尽量避开隆起发育区.

South Sichuan is the main area of shale gas exploration and development in China, and its output is expected to exceed 10 billion cubic meters in 2020. However, the production of horizontal wells in different regions is different, which is closely related to the target location and drilling encounter rate. Based on the study of reservoir quality, combined with the characteristics of easy cracking shale and the distribution of high carbonate shale, we point out the location and suggestions of target in South Sichuan. The conclusions are as follows: (i)The best quality reservoir is defined as type Ia, which is mainly distributed at the bottom of Longmaxi Formation and there are obvious differences in the distribution of high-quality reservoirs. (ii)The easily fractured layer is mostly the layer with high graptolite abundance, and the type Ia develops many lamellation which is easy to crack and affects the vertical extension of fractures at the bottom of Longmaxi Formation. (iii)A thin layer of high carbonate-content shale, with high compressive strength is developed on top of type la reservoir, which is not easy to be fractured. In order to maximize the shale reserves at the bottom of Longmaxi Formation, the target should be below the high carbonate-content shale. However, the influence degree of different regions of this interval is different, from large to small: WeiYuan > Changning > Luzhou. (iv)The reservoir with good quality, easy to crack, and located below the high carbonate interval is selected as the target location. In WeiYuan, it is recommended to locate in the middle or lower Long1(1)(1). It is recommended to the lowerLong 1(1)(1) to Long1(1)(2)in Changning. Luzhou is recommended to be located in the reservoir with the best shale quality. The above conclusions can effectively guide the target location optimization of horizontal wells, improving the shale gas production of horizontal wells in South Sichuan.