--> Abstract: Fault Pattern and Oil Migration in Huang Hua Depression, China, by G. Zhou; #90984 (1994).

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Abstract: Fault Pattern and Oil Migration in Huang Hua Depression, China

Guojun Zhou

Huang Hua depression is a back-arc intercratonic rift basin that developed on the north China platform in the Cenozoic. Controlled

by the basement anisotropy, multidirectional fault sets on the plane are developed along the preexisting zone of weakness. According to the scale of tectonic elements controlled by faults, as well as its time of activity and depth, normal faults are divided into four grades in this basin. Seismic data and geological information have shown that 70% of the faults are listric faults. Flattening of the faults reflects tilting of fault block or detachment along the unconformity surfaces and ductile beds. Because of gravity creep and local extension, main faults and secondary faults are united into "horse tail" or "Y" patterns.

Results of oil--source rock correlation and oil migration parameters all demonstrate that oil and gas migrate in or through faults (fracture zones), and form the "step-like" migration model. Faults in sandstone-shale sequences play the role of conduits for hydrocarbon, but faults in gypsum beds and thick undercompacted shales generally act as a top seal. To prevent oil migration through faults, reservoirs and ductile rocks with a high capillary displacement pressure must be juxtaposed. Whether faults are rejuvenated during hydrocarbon migration is not required for faults opening, but it is important to investigate the activity history of growth faults and the role of juxtaposed sediments in a sandstone-shale sequence in creating sealing and nonsealing faults.

AAPG Search and Discovery Article #90984©1994 AAPG Annual Convention, East Lansing, Michigan, September 18-20, 1994