三塘湖盆地条湖组沉凝灰岩致密油有效开发技术

三塘湖盆地中二叠统条湖组沉凝灰岩致密油分布稳定,天然裂缝发育,储集层具中—高孔、特低渗的特征,结合近年来研究区致密油勘探取得的成果,分析有效开发面临的技术性难题;采用水平井+体积压裂技术虽然实现了储量整体动用,但产量递减快,一次采收率低,开发效益差。为探寻类似致密油高效开发技术路线,逐步探索出快速补充地层能量注水吞吐技术,缩小井距,实现井间缝网搭接的缝控储量井网加密技术,加密后,由单井吞吐转向井组渗吸+驱替注水技术。采用以上技术,解决了多井低产的问题,采收率由2.5%逐渐提高至10.2%,采油速度保持在1.0%,达到了相对高效开发的目的,并实现了效益开发。形成的技术理念对类似致密油的有效开发具有借鉴意义。

Efficient Development Technologies for Tight Oil in Tuffite Reservoirs in Tiaohu Formation of Santanghu Basin

The tight oil in the tuffite reservoir of Tiaohu formation in Santanghu basin is distributed stably. The reservoir is characterized by medium to high porosity, ultra-low permeability and high oil saturation and developed natural fractures. Based on the achievements of tight oil exploration in the study area in recent years, technical problems related to efficient development were analyzed. It was found that the technology system of horizontal well plus volume fracturing could stimulate the overall producing of reserves, but the production decline was fast, the primary recovery was low and the development benefit was poor. Finally several technologies were proposed, such as cyclic water injection for rapidly replenishing formation energy, infill wells for reducing well spacing and expanding fracture controlled reserves. After well pattern infilling, cyclic water injection in individual wells was converted to well-group water flooding. Finally, the oil production has been improved in many wells, the recovery has been increased from 2.5% to 10.2%, and the production rate has been kept at 1.0%. Efficient and profitable reservoir development has been realized. The results can be references for developing similar tight reservoirs.