Abstract:

Mud stone and shale from the Lower Section of Es3 in Bonan Subsag, Jiyang Depression is characterized by great thickness and wide distribution. It mainly develops dark gray mudstone, lime mudstone, oil mudstone, argillaceous limestone, and yellow brown and taupe oil shale. The mud stone and shale has high content of organic carbon (up to 9.0%) and great hydrocarbon generation potential (up to 82.6 mg/g) as well as high maturity (up to 3.0%), which made it as good source rocks and also a favorable accumulation area for shale oil and gas. To study the reservoir space of mud stone and shale of the lower section of Es3, methods such as core observation, polarizing microscope, scanning electron microscope and so on were applied. The cracks of shale reservoir space include structural cracks, microcracks between layers, overpressure breaking cracks. The pore space is mainly micropores, including pyrite intergranular pores, intergranular pores of clay minerals. Overall, reservoir space is dominated by tension fracture microcracks between layers, intergranular pores of clay minerals, intergranular pores of calcite. Through the comparison of reservoir space types and characteristics of different rocks, the lamellar argillaceous limestone in Lower No.12 and Upper No.13 layers of Es3 is the best reservoir lithofacies style.

Key words: Bonan Subsag, mud stone and shale, microcracks, micropores, shale oil and gas