Geochemical characterization of Lucaogou Formation and its correlation of tight oil accumulation in Jimsar Sag of Junggar Basin, Northwestern China

Jiangxiu Qu,Ming Zha,Zimeng Wang,Hong Chen,Xiujian Ding,Changhai Gao

doi:10.1007/s13202-017-0335-1

Abstract

With the constant consumption of conventional oil and gas resources, unconventional oil and gas resources with great resource potential such as tight oil have gradually been valued and become the new exploration area. Jimsar Sag is the key tight oil exploration and development block in Junggar Basin of Northwestern China. Based on the data sets of geology, oil production test, logging, rock thin section, and geochemistry of Permian Lucaogou Formation (LCG), we studied the geochemical characteristics of hydrocarbon source rocks and their relation to the tight oil accumulation. Organic matter abundance of source rocks is high, the types of organic matter are mainly type I and type II, and the organic matter maturation is in the low mature stage to mature stage. Results of oil source correlation showed that the crude oil of sweet spots was mainly derived from the source rocks in the interior of the sweet spots. The LCG tight oil is mainly distributed in the plane where the source rocks have great thickness and the TOC is higher than 3.5%. It shows that the source rocks have obvious controlling on the occurrence and accumulation of tight oil.

Highlights

With the successful exploitation of Bakken oil (Williston Basin, North America; Miller et al 2008) and Eagle Ford oil (South Texas) (Mullen 2010), tight oil has been a research focus in global petroleum geology (Johnstone 2007; Zou et al 2013; Hill et al 2007) and was considered the most practical unconventional replacement for oil and gas besides shale gas (USGS 2008; Cao et al 2016a, b)
Based on the data sets of geology, oil production test, logging, rock thin section, and geochemistry of Permian Lucaogou Formation (LCG), we studied the geochemical characteristics of hydrocarbon source rocks and their relation to the tight oil accumulation
The LCG tight oil is mainly distributed in the upper and lower sweet spot, where in upper sweet spot source rocks total organic carbon content (TOC) is mainly distributed in the range of 2–8%, lower sweet spot source rocks TOC is mainly distributed in the range of 0.5–6%, and non-sweet spot hydrocarbon source rocks TOC is mainly distributed in the 0.5–4%

Summary

Introduction

With the successful exploitation of Bakken oil (Williston Basin, North America; Miller et al 2008) and Eagle Ford oil (South Texas) (Mullen 2010), tight oil has been a research focus in global petroleum geology (Johnstone 2007; Zou et al 2013; Hill et al 2007) and was considered the most practical unconventional replacement for oil and gas besides shale gas (USGS 2008; Cao et al 2016a, b). In recent years much progress has been made in tight oil exploration of the Permian Lucaogou (LCG) Formation, which is the primary exploratory stratum of tight oil reservoirs in the Jimsar Sag, Junggar Basin, Northwestern China. The Lucaogou Formation in Jimsar Sag, which formed in the sedimentary environment of a lacustrine basin, is a set of mixed fine-grained deposits. Siltstones, sandstones, and dolomites are the main rock types with the characteristics of fine grains, thin single layers, and frequently alternating lithology

Methods

Results

Conclusion