Buried-Hill Discoveries in Damintan Depression of North China Basin

Tong Xiaoguang, Huang Zuan

The Damintan fault depression is about 20 km west of Shenyang, Liaoning Province, North China, and is a small Tertiary continental depression, covering only about 800 km². In the depression, the Tertiary system unconformably overlies upper-middle Proterozoic sedimentary rocks and Archean metamorphic rocks.

The Tertiary system is up to 6,600 m in thickness. Source rocks are in the third and fourth members of the Eocene Shahejie Formation. Buried-hill traps were formed in Proterozoic carbonates and metamorphic rocks of the Archean. Fault block, stratigraphic, and lithologic traps also occur in sandstones of the Shahejie Formation, especially in those of the third member.

Several buried-hill-drape traps occur in the depression. The various types of oil pools in each buried-hill-drape trap constitute a complex hydrocarbon accumulation zone. A series of oil fields have been found in the depression. The crude oil is characterized by high wax content and high pour point.

Hydrocarbon exploration began in 1971, but only a few small oil fields were found in the 1970s. Recently, by applying digital seismic techniques, the subsurface geological structure has been accurately mapped and new production technology has enabled the high-pour-point oil to be produced. Thus, important achievements in hydrocarbon exploration were made during the 1980s.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.