四川盆地川中侏罗系致密储层石油勘探前景

Petroleum exploration prospect of the Jurassic tight reservoirs in central Sichuan Basin

从连续型石油聚集和与美国Williston盆地Bakken组对比的角度，对四川盆地川中侏罗系致密储层的石油勘探前景进行了探讨。研究认为：1）四川盆地侏罗系储层孔隙度平均为1．O％-3．7％，渗透率平均为0．35×10^-3-0．53x10^-3μm。，中值孔喉半径平均为0．05-0．24μm，属于典型的致密储层。2）川中侏罗系产油层纵、横向上与生油层密切共生，源内或近源聚集；主力油层连续分布在斜坡区和凹陷区，没有明显的圈闭界限，不受局部构造控制；多层系叠合连片，大面积整体含油；多数含油区块为异常高压系统，油藏无水，没有统一的油一水边界，为较典型的连续型石油聚集，与Bakken组基本相同。3）Bakken组致密储层石油在近几年相对高油价背景下，主要以水平井及分段压裂技术实现了规模效益勘探开发；川中侏罗系受认识、投入和技术的制约，近十几年来未有实质性进展。4）从研究认识着手，建立先导性试验区，加强水平井及分段压裂等关键工艺技术攻关，有效提高单井产量，这是打开川中侏罗系致密储层石油勘探开发新局面的有效途径。

From viewpoint of continuous petroleum accumulation and comparison with Bakken Formation in Willsiton Basin（USA） ,the paper discussed petroleum exploration prospect of the Jurassic tight reservoirs in central Sichuan Basin. The Jurassic reservoirs in Siehuan Basin are typical tight ones with an average porosity of 1 - 3.7% ,average permeability of 0.35 ×10^-3-0.53× 10^-3μm and median pore throat radius of 0. 05 -0.24 mm. The Jurassic reservoirs contacte closely with source rocks both laterally and vertically in central Sichuan Ba- sin. The hydrocarbons accumulates within source rocks or in reservoirs close to the source rocks. The major reser- voirs are continuously distributed in the slope area and sags, have no distinct trap boundaries, and are not con- trolled by local structures. Multiple reservoirs superimposed vertically and connected laterally, forming a large hydrocarbon-bearing areal extent . Most oil-bearing blocks have an abnormal overpressure system, no water in the reservoir and no uniform oil/water contact. The Jurassic oil accumulation in central Sichuan Basin is a typical continuous one basically similar to the Bakken Formation. In recent years, the Bakken tight oil have been deve- loped in large scale with horizontal well and multi-stage fracturing techniques thanks to the relatively high oil price. In contrast, exploration and development of the Jurassic tight reservoirs in central Sichuan Basin have no breakthrough due to the constraints of understanding, investment and technology. Improving geological under-standing, strengthening research of key technologies such as horizontal drilling and multi-stage fracturing and in- creasing single well production are critical to the successful exploration and development of the Jurassic tight re- servoir in central part of Sichuan Basin.