Well GS78 is one of the high oil and gas production wells in
Bohai Bay basins. It reached more than 600 m3/ d ,while its oil
reservoir is thin , its burial deepth is large , and its reservoir
properties is low. Its high production is related to fracture through
well , structure , ground stress , pore fluid pressure , and load
pressure research. Single stratum thickness , lithology , content of
clay minerals and distance to major faults affected the
development of fracture ,There are mainly two causes of forming
fracture ,one is structure movement ,the other is high pore fluid
pressure , The structure fracture formed early , so they mostly
closed. The high pore fluid pressure fracture formed later ,so they
keep to open. The case shows that enriched and high2production
oil and gas field can be found in areas where sedimentary facies
is not so good ,thickness of sand bodies is thin ,reservoir properies
is low ,but overpressure developed.