TITLE:
Comprehensive Evaluation of Geological and Engineering Sweet Spots of Shale Gas Reservoir: A Case Study of the Luzhou Block, Sichuan Basin
AUTHORS:
Yuan Wang, Jianfa Wu, Li Fu, Haoyong Huang, Gang Chen, Cheng Chang
KEYWORDS:
Deep Shale Gas, Geological Sweet Spots, Engineering Sweet Spots, Geomechanical Modeling
JOURNAL NAME:
International Journal of Geosciences,
Vol.12 No.11,
November
16,
2021
ABSTRACT: There is
a huge amount of marine shale gas resources in the southern Sichuan Basin in
China, and most of the resources are at the buried depth of 3500 - 4500 meters. At present, deep shale gas is in the
early stage of exploration and development. In order to achieve large-scale
efficient development, in addition to optimizing favorable blocks, it is also
to identify the optimal target in the vertical direction combine geology,
drilling, and fracturing. Therefore, Taking the Longmaxi formation shale in the
Luzhou block as the research object, based on drilling, logging, and core
experiment data, through single well and 3D geomechanical modeling methods,
analyze the characteristics of organic matter abundance, porosity, pore
pressure, collapse pressure, mineral composition and in-situ stress of
different layers of shale in Longmaxi formation. Systematically summarized the
main controlling factors of the “sweet spot” of deep shale gas and establish
the comprehensive evaluation system of deep shale gas “sweet spots”, to clarify
the optimal “sweet spots” of geology, drilling, and fracturing in the Longmaxi
reservoir. Results show that the total organic carbon content, porosity, and
gas saturation of the long111 layer are higher than other layers. The Long111
layer has a low collapse pressure and a high compressive strength, the risk of
wellbore instability is relatively low. The stress difference coefficient of
All layers is less than 0.3, and the brittleness index of the Long111 layer is
62.35%. A complex fracture network is easier to form after fracturing. The
conclusion shows that the Long111 layer is the optimal reservoir section of the
Longmaxi Formation. Ensure the drilled rate of the Long111 layer and maximize
the length of the horizontal section can obtain higher production.