GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 114-11
Presentation Time: 10:50 AM


MA, Debo, Department of Petroleum Exploration, Research Institute of Petroleum Exploration & Development, PetroChina, 20 Xueyuan Road, Haidian District, Beijing, 100000, China and HE, Dengfa, CUGB, Beijing, 100083, China,

Tarim Basin is one of the largest oil and gas bearing basins in China. Halahatang oilfield located in the north of Tarim Basin is a large carbonate oil field discovered in recent years. The main reservoir types are fracturing and karsting carbonate reservoirs controlled by strike-slip faults.

The seismic data used in this paper are acquired by Tarim Oilfield Company in 2010. The Eigen-structure coherency and SO semblance are used to identify the distribution of the strike-slip fault.

There were several groups of strike-slip faults trending Northeast and Northwest in this area. Nine kinds of typical structural styles of strike-slip fault were founded such as Tulip/Palm tree structure and En-echelon structure. On the plane, the master strike-slip faults were conjugate shear faults like chessboard, and secondary faults extending shortly intersected with the master faults at a small angle. Single strike-slip fault had segmentation, so different parts had different structural styles in one strike-slip fault.

Judging form the age of rocks subjected to strike-slip dislocation and the structutal styles in different strata, the strike-slip faults had three epochs of activity in Halahatang area. In Late Ordovician period, the strike-slip faults were formed as conjugate strike-slip faults by pure shear. That was caused by a pulse of horizontal pressure along the north-south direction due to the closure of the West Kunlun ocean. In Late Permian period, some NW trending Ordovician strike-slip faults were reactivated and generated normal faults in Late Paleozoic strata. The normal faults converged downward to the Ordovician strike-slip faults vertically. In Late Cretaceous period, some NE trending Ordovician strike-slip faults were reactivated and en-echelon faults were formed in Mesozoic strata. The En-echelon fault systems forming spatial “Tulip” structures are the most distinctive feature and principal diagnostic indicator for the strike-slip faults. They have more gentle dip angles ranging from 40°to 60°in the upper part of the section and steeper angles ranging from 70°to 90°in the lower part. Individual faults extend vertically down to the Ordovician strike-slip faults.

The strike-slip fault systems controlled the distribution of hydrocarbon in Halahatang oilfield.