川西彭州地区雷口坡组沉积期后古应力场重建及其油气地质意义

川西坳陷三叠纪以来多期构造应力场演化控制了该区古隆起的迁移和裂缝-岩溶型储层的形成，从而对该区油气富集具有十分重要的控制作用，而目前对该区古构造应力场的量化评价研究程度较弱。通过野外露头、钻井岩芯、薄片及裂缝充填物以及声发射测试资料，重点对川西坳陷彭州地区雷口坡组沉积后期的古应力方向、大小及演化期次进行了研究。结果表明该区域存在4期应力，印支期应力为NW向；燕山早中期应力为SN向；燕山晚期应力为NW向；喜山期应力为EW向。对应的最大水平应力值分别为25.81MPa、66.03MPa、41.27MPa以及50.85MPa。结合区内构造演化，印支期区域平缓抬升使得古隆起及彭县断裂雏形形成，雷口坡组暴露地表形成岩溶性储层，成为后续的油气富集地；在燕山期两期应力控制下，研究区北部地层最先抬升，古隆起继续发育；喜山期强烈构挤压下使全区北西向地层抬升，古隆起最终定型，燕山晚期-喜山期形成的裂缝和断层对早期油气运移进行调整起到关键作用。该研究可为彭州地区的构造演化、裂缝预测以及进一步的勘探开发提供依据。

Reconstruction of paleostress field after the depositional period of Leikoupo Formation in the Pengzhou area, western Sichuan and its oil and gas geological significance

The evolution of multi-stage paleo stress field has controlled the migration of paleo-uplift and the formation of fracture-karst reservoir since the Triassic in the Western Sichuan Depression, which plays an important role in controlling the accumulation of oil and gas in this area. However, the quantitative evaluation of the paleo stress field in this area is weak at present. Based on field outcrops, drilling cores, thin sections and fracture fillings, the study focused on the paleo stress direction, magnitude and evolution stage of the Leikoupo Formation in the later depositional stage of the Pengzhou area of the Western Sichuan Depression. The results show that there are four periods of stress in this area. The stress direction in the Indosinian period is NW; the stress direction in the early and middle Yanshan is SN; the stress direction in the late Yanshan period is the NW; the Himalayan period is near EW. The corresponding maximum horizontal stress values are 25.81MPa, 66.03MPa, 41.27MPa and 50.85MPa, respectively. Combined with the tectonic evolution in the Pengzhou area, the gentle uplift of the Indosinian period resulted in the formation of the paleo-uplift and the Pengxian fault, the exposed surface of the Leikoupo Formation formed karst reservoirs, which became the subsequent oil and gas enrichment space and migration channel; under the control of the two phases of Yanshanian stress, the strata in the northern part of the study area were uplifted first, and the paleo-uplift continued to develop; The strong tectonic compression in the Himalayan period uplifted the NW-trending strata in the whole area, the paleo-uplift was finally shaped, and the fractures and faults formed played a key role in the adjustment of early oil and gas migration. This study can provide a basis for the structural evolution, fracture prediction and further exploration and development in the Pengzhou area.