Basin-mountain tectonic pattern and hydrocarbon exploration domain in north margin of Qaidam Basin

Abstract

Seismic profile crossing southern boundary of Saishiteng Mountain shows the shear tectonic characteristic of fault zone at southern boundary of Saishiteng Mountain. In the west of Saishiteng, the fault zone thrusts towards top and north; in the center, the fault zone shows high angle, in the east (line 1001 profile), it represents as low-angle and basin-toward thrusted fault, which may be converted structure at the end of strike-slip faulted structure, in pattern of associated structure. The north boundary did not overthrust to basin; Wells Dongtai 1 and Gaqiu 1 at foothill of Saishiteng did not penetrate into new formations overlapped by the mountains but into associated products of high-angle faulted structure, which indicates that the mountain was less thrusted to the basin. So the structure deformation of Northern Qaidam Basin had been mainly strike slip since Cenozoic and the thrust nappe is associated with the strike-slip structure. The strike-slip faulted zone in north boundary showed reversal deformation, so it is not a favorable play to form original reservoirs; the masses between strike-slip trips that may be stable relatively, are favorable for forming reservoirs. Key words: Northern Qaidam Basin, strike-slip faults, overthrust, structural conversion, hydrocarbon exploration