Continuous hydrocarbon accumulation over a large area as a distinguishing characteristic of unconventional petroleum: The Ordos Basin, North-Central China

Abstract

Global petroleum exploration is currently undergoing a strategic shift from conventional to unconventional hydrocarbon resources. Unconventional hydrocarbons in tight reservoirs show characteristics distinct from those of conventional hydrocarbon sources hosted in structural and stratigraphic traps. The characteristic features include the following: a hydrocarbon source and reservoir coexist; porosity and permeability are ultra-low; nano-pore throats are widely distributed; hydrocarbon-bearing reservoir bodies are continuously distributed; there is no obvious trap boundary; buoyancy and hydrodynamics have only a minor effect, and Darcy's law does not apply; phase separation is poor; there is no uniform oil-gas-water interface or pressure system; and oil or gas saturation varies. Examples of unconventional hydrocarbon accumulations are the Mesozoic tight sandstone oil province and the Upper Paleozoic tight sandstone gas province in the Ordos Basin, north-central China. Generally, continuous hydrocarbon accumulation over a large A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT 2 area is a distinguishing characteristic of unconventional hydrocarbon sources.Because of the great potential of unconventional petroleum resources, it is believed that research on such resources will be at the forefront of the future development of petroleum geology.

Prediction of Diagenetic Facies using Well Logs: Evidences from Upper Triassic Yanchang Formation Chang 8 Sandstones in Jiyuan Region, Ordos Basin, China

“…It is confirmed that there are abundant petroleum resources in the Ordos basin, continuously distributed over a large area: the Jurassic-Triassic petroleum system, and the Upper Paleozoic and Lower Paleozoic natural gas systems (Shuai et al, 2013;Zou et al, 2013b). The mudstones and oil shales of the Chang 7 subsection are thought to be the best source rocks for Jurassic-Triassic petroleum system (Duan, 2012), the source rocks contain dominantly type I (oil prone) organic matters, with Ro values of 0.66-1.07% (Yang et al, 2005).…”

Fine-grained and coarse-grained Paleogene sublacustrine fan systems in Fushan Depression, Beibuwan Basin, South China Sea: implications for sedimentary characteristics and depositional processes

“…Commonly, the sedimentary source supply can be identified by the integration of the occurrence of peripheral river systems, heavy mineral analysis, seismic properties, and regional tectonic evolution (Zou et al 2013). These materials, however, are lacking and imperfect for this study.…”

Prospect of Ultra-Deep Petroleum Onshore China

“…Such as in the ultra-deep formations of Tarim Basin, microcrystal quartz and calcite films retained the primary pores. The research on the Yanchang Formation of Ordos Basin and Xujiahe Formation of Sichuan Basin showed the distribution zone of chlorite well-developed would have better reservoir properties, proving the protection function of clay film to primary pores Lan et al, 2011;Zou et al, 2013).…”