Oil-Shale Mining in Maoming Basin of China

Hugh J. Mitchell-Tapping

The Maoming basin in Guangdong Province is one of the major oil-shale mining areas of China and is situated about 300 km southwest of Hong Kong. This Tertiary basin produces oil from shales mined from a 5-km long open-faced pit on the crest of an anticline in the center of an uplifted and tilted graben. The oil shale extends about 30 km in a northwest-southeast line, and the beds dip as much as 10° toward metamorphic mountains to the northeast. In the surrounding area are numerous oil seeps, especially in ponds, water wells, and at the foundations of buildings. Holes with oil shows, made to test the extent of the oil shale, have been drilled to a depth of 1,000 m. At the base of the mine face is a limestone hardground on top of which is a coal seam about 0.5 m thick hat can be traced throughout the basin. Atop this Paleocene coal bed are Eocene oil-shale and thin sandstone beds in five repeated sections, each about 15 m thick, called the Youganwou formation. All kinds of freshwater fossils--fish, insects, plants, turtles, and tree trunks--are found in a near-perfect state of preservation in these oil-rich shales and coal sections. The estimated oil content of the rock is about 8% of good-quality oil with plenty of light ends. The organic matter in the oil shale is derived from planktonic algae such as Pediastrum. In samples from sections parallel with the bedding plane, the Pediastrum-type lamalginite content is as great as 30% of the organic matter, with colonies up to 0.1 mm in diameter. The overlying sandstones are friable and very iron rich, and they contain dispersed clays, large tan to dark gray clay balls, and some rounded quartz pebbles about 0.35 m in diameter. The Oligocene Huangniuling formation overburden consists of white to red conglomerates and sandstones containing laminated and dispersed clays. At the mine this formation is about 45 m thick and is disconformable to the Eocene Youganwou formation. The claimed oil output from the oil shale is about 700,000 bbl of oil/year since 1958 with Chinese estimates of enough oil shale to last 150 years.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.