About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

DOI: 10.1306/08031817416

Lithofacies and depositional setting of a highly prospective lacustrine shale oil succession from the Upper Cretaceous Qingshankou Formation in the Gulong sag, northern Songliao Basin, northeast China

Bo Liu,1 Haoli Wang,2 Xiaofei Fu,3 Yunfeng Bai,4 Longhui Bai,5 Mengcheng Jia,6 and Bo He7

1Accumulation and Development of Unconventional Oil and Gas, State Key Laboratory Cultivation Base (jointly constructed by Heilongjiang Province and Ministry of Science and Technology), Northeast Petroleum University, Daqing, China;
2State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, China; present address: Department of Earth Science, Northeast Petroleum University, Daqing, China; [email protected]
3Accumulation and Development of Unconventional Oil and Gas, State Key Laboratory Cultivation Base (jointly constructed by Heilongjiang Province and Ministry of Science and Technology), Northeast Petroleum University, Daqing, China;
4State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, China; [email protected]
5Accumulation and Development of Unconventional Oil and Gas, State Key Laboratory Cultivation Base (jointly constructed by Heilongjiang Province and Ministry of Science and Technology), Northeast Petroleum University, Daqing, China; [email protected]
6PetroChina Daqing Oilfield Company, Daqing, China; [email protected]
7Accumulation and Development of Unconventional Oil and Gas, State Key Laboratory Cultivation Base (jointly constructed by Heilongjiang Province and Ministry of Science and Technology), Northeast Petroleum University, Daqing, China;
8State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, China; [email protected]
9PetroChina Daqing Oilfield Company, Daqing, China; [email protected]
10PetroChina Daqing Oilfield Company, Daqing, China; [email protected]

ABSTRACT

The lacustrine shale of the Upper Cretaceous Qingshankou Formation is the principal prospective unconventional target lithology, acting as source, reservoir, and seal. Lithofacies and associated storage capacity are two significant factors in shale oil prospectivity. This paper describes an investigation of the lower Qingshankou Formation lacustrine shale based on detailed description and analysis of cores, shale lithofacies characteristics, depositional setting, and stacking patterns.

Seven lithofacies are recognized based on organic matter content, sedimentary structure, and mineralogy, all exhibiting rapid vertical and lateral changes controlled by the depositional setting and basin evolution. An overall trend from shallow-water to deep-water depositional environments is interpreted from the characteristics of the infilling sequences, characterized by increasing total organic carbon (TOC) and total clay content and decreasing layer thickness (i.e., from bedded to laminated then to massive sedimentary structures). Periods of deposition during shallowing cycles show a reverse trend in the sedimentary characteristics described above. The sedimentary rocks in the studied interval show three complete short-term cycles, each one containing progressive and regressive system tracts.

Massive siliceous mudstones with both high and moderate TOC are considered to have the best hydrocarbon generation potential. Laminated siliceous mudstones, bedded siltstones, and calcareous mudstones with moderate and low TOC could have the same high hydrocarbon saturations as the high-TOC massive siliceous mudstones, but these lithologies contain more brittle minerals than the massive mudstones. Several siltstone samples show low or zero saturation of in situ hydrocarbons; this is considered to be related to a combination of fair to poor hydrocarbon generation potential and extremely low permeability, limiting migration. Moderate-TOC laminated siliceous mudstones were also observed to have connective pore-fracture networks. It can be demonstrated that successive thick sequences of moderate-TOC laminated siliceous mudstones, showing high volumes of hydrocarbon in situ, a high mineral brittleness index, and good permeability, combine to form shale oil exploration “sweet spots.”

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Protected Document: $10
Internal PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].