Abstract:

As petroleum exploration goes into a more and more mature stage, deep clastic reservoir is becoming an important new area for exploration in the oil-gas basins. The research of deep petroleum exploration is focusing on the mechanism of the clastic reservoir evolution. The formation mechanism of the deep effective clastic reservoir is complex and closely connected to the sedimentation, diagenesis and tectonism. Sedimentary environment is the prerequisite and foundation for forming effective reservoir. Secondary pore produced by the main constructive digenesis vastly improves reservoir physical properties. Depositional environment and diagenetic conditions that can prevent or slow down diagenesis effectively is conductive to the reservoir physical properties, including low geotemperature, rapid burial history, abnormal pressure, gypsum-salt bed effect, hydrocarbon inject, grain coats and fluid activity, etc. During the evolution of deep reservoirs, tectonic compaction reduces the pore volume, while the structural fractures improve the seepage ability of the reservoir porosity, forming effective fractured reservoir. Thus, the reservoir forming mechanism was suggested with the deposition, dissolution and tectonism being fundamental, key and occasion respectively. Through using modern technology, conducting the diagenesis modeling experiments and using new methods with the inter-discipline knowledge, have already become the main development trends of the research of the forming mechanism of the deep effective clastic reservoir.

Key words:  sedimentary facies, unconventional reservoirs, favorable areas prediction, Lower Jurassic, Ziliujing Formation, Da’anzhai member, Fuling demonstration area