Author(s): Fu Guang, Xia Yunqing, Northeast Petroleum University
Pages: 11-17
Year: 2013 Issue:  10
Journal: Natural Gas Industry
Keyword:  fault; fault-rock seal; fault juxtaposition seal; lateral sealing; forming condition; difference; oil(gas)-water contact; Banqiao Fault;
Abstract: Lateral fault seals in clastic sequences can be divided into two types,namely fault-rock and fault-juxtaposition seals.In order to correctly understand the role of faults in hydrocarbon accumulation and distribution,apioneer comparative study was performed on the sealing mechanisms and sealing conditions of the aforementioned two types of lateral seals.Findings showed that for the traps formed under the influence of lateral fault-juxtaposition seals,their oil(gas)-water contact distributions are controlled by the lithologies of juxtaposed rocks.In contrast,for the traps formed under the influence of lateral fault-rock seals,their oil(gas)-water contract distributions are controlled by the displacement pressure of fault rocks.The lateral fault-juxtaposition seals are significantly better than the lateral fault-rock seals in sealing capacities.In a case study of the Banqiao fault in the Qikou sag,Dagang Field,we found that under the same conditions,the sealing capacity of lateral fault-juxtaposition seals is 25 to 43times larger than that of lateral fault-rock seals.This significant difference results in the accumulation of gas in the upper part of the 1st member of the Paleogene Shahejie Fm sealed by the lateral fault-juxtaposition seals,while the accumulation of oil in the lower part of the 1st member of the Paleogene Shahejie Fm sealed by the lateral fault-rock seals.