Source Rock Characteristics and Hydrocarbon Potential of Middle Permian P2p Source Rocks in the Kelameili Area, Eastern Junggar Basin, NW China: Implications for Tight Oil Exploration

Abstract

As the most important source rocks in the Eastern Junggar Basin, Middle Permian Pingdiquan (P2p) source rocks have been gaining increasing attention after the discovery of the tight oil in Shazhang uplift. To meet requirements for further P2p tight oil exploration in the Eastern Junggar Basin, it is necessary to analyze and reexamine the organic matter abundance, type and thermal maturity, hydrocarbon potential and sedimentary environment, based on geochemical data from 113 core samples of 34 exploration wells. The Pingdiquan (P2p) source rocks are widely distributed (up to 7, 546 km2) and have an elevated thickness in the Eastern Junggar Basin. Geochemical analysis results indicate that the P2p source rocks are fair to good source rocks dominated by type II kerogen and are in the low mature-mature stage. Integrated analysis of P2p formation's biomarkers and trace elements indicates that P2p formation was deposited in a terrestrial coastal environment under oxic to dysoxic, and fresh to brackish conditions, with probable intermittent seawater influence. Based on hydrocarbon expulsion modelling, hydrocarbon expulsion began at 0.87% Ro and peak expulsion occurred at 1.1% Ro. Hydrocarbon generation intensities in Shazhang uplift and Wucaiwan Sag are relatively large, with values centred at (400-650)×104t/km2 and (400-600)×104 t/km2, respectively. Shazhang uplift and Wucaiwan sag are two hydrocarbon expulsion centres in the study area, and the largest hydrocarbon expulsion intensity centre lies in the Shazhang uplift, exceeding 300×104t/km2. The amount of hydrocarbon generation and expulsion from the P2p source rocks was approximately 45.6×108 t and 14.4×108 t, respectively, indicating significant tight oil exploration potential in the Eastern Junggar Basin. It is validated by exploration process that the area with high hydrocarbon expulsion intensity is a favorable target for tight oil accumulation and exploration.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017