费尔干纳盆地超深层油气成藏系统

Ultra-deep petroleum accumulation systems in Fergana Basin

徐洪 杨玉峰

Xu Hong Yang Yufeng

中国石油 天然气勘探开发公司, 北京 100034

China National Oil-Gas Exploration & Development Corporation, Beijing 100034, China

费尔干纳盆地中央地堑带新生界中普遍发育超高压异常，其与构造挤压环境、快速沉降不均衡压实以及持续的生烃作用有关。这种超高压环境对深层油气的生成、聚集成藏产生了重要的影响。主要目的层新近系埋深超过5 000 m，仍以液态烃产出，深层高孔高渗类砂岩储层是河道砂岩在超高压环境下未经正常压实形成的，表现为取心收获率低、生产过程中易出砂的特征；而低孔高渗类储层与高压形成的水力破裂裂缝有关。古近系碳酸盐岩储层中高含硫化氢气体来源于TSR反应，TSR作用使含石膏碳酸盐岩储层物性得到了显著的改善，其油层组压力系数稍低于新近系油层组是重烃类气体损耗、储集空间增大两方面因素叠加的结果。中央地堑带主要目的层成藏系统划分为上部E-E3N系统和下部JK-E1-2系统；上部高产储层主要受河道砂岩和超高压控制，下部高产层主要受潟湖相的含石膏碳酸盐岩储层控制，2个含油气系统的压力、流体性质均有较大的差别，适宜于分层开采。

In the central graben zone of the Fergana Basin, overpressures were widespread during Cenozoic, which might be related to tectonic compression environment, disequilibrium compaction caused by quick sedimentation and continuous hydrocarbon generation. The ultra-high pressure environment had important effects on deep oil and gas generation, migration and accumulation. The main reservoirs were buried over 5 000 m deep in Neogene, and mainly gave birth to liquid hydrocarbons. The high-porosity and high-permeability sandstone reservoirs in deep formations came from fluvial sandstones under ultra-high pressure, and were featured by low coring recovery rate and high sand production. The low-porosity and high-permeability reservoirs were related to hydraulic fractures caused by high pressure. In the carbonate reservoirs in Paleogene, H2S was in high content, mainly generating from thermochemical sulfate reduction (TSR), which obviously improved the physical property of gypsum carbonate reservoirs. The formation pressure coefficient was slightly lower than that of Neogene, which could be explained by heavy hydrocarbon gas loss and reservoir space increase. The main petroleum systems in the central graben zone can be divided into the upper E-E3N system and the lower JK-E1-2 system. High-production reservoirs of the upper E-E3N petroleum system are controlled by channel sandstones and overpressure, while those of the lower JK-E1-2 petroleum system are mainly affected by the gypsum-containing carbonate reservoirs of lagoon facies. The two systems are totally different in pressure and fluid properties, hence are suitable for slicing production.

https://doi.org/10.11781/sysydz201404450