Haitao Xue

Classification and evaluation criteria of shale oil and gas resources: Discussion and application

Abstract Research on the evaluation criteria of shale oil and gas is conducted to accurately assess the resource potential of shale oil and gas. Statistic analysis of the geochemical index of hydrocarbon source rocks in five areas such as Songliao, Hailaer, Jiyang, based on the characteristic of triple-division between the oil content and TOC of source rock, suggests that shale oil and gas can be categorized into three levels of resource enrichment: scattered (ineffective) resources, low efficient resources and enriched resources. The mature stage, at which organic matter generates oil and gas in large amounts, corresponds to the shale oil and gas enrichment window. Furthermore, recoverable index is defined and its computation formula is proposed to provide a quantitative index for recoverability evaluation, considering the brittle mineral content, thickness and depth of shale, etc. In practice, TOC variable values in well profile obtained by TOC -logging correspondence can be used to draw TOC isopach maps and calculate the amount of resources at different levels. Then combined with the evaluation criteria, TOC and R o isopach maps are superimposed to identify the favorable shale oil and gasareas.

Microstructural characteristics of the Cretaceous Qingshankou Formation shale, Songliao Basin

Abstract To research the characteristics and petroleum geological significance of micro pores, this paper uses Second Electron Microscope (SEM) and secondary SEM imaging capability in Field Emission SEM (FE-SEM) to characterize shale from the first member of the Cretaceous Qingshankou Formation, Songliao Basin. There are five major pore types in the shale, including matrix intercrystal, organic, dissolution, interparticle, and intracrystalline pores. In addition, there are a mass of micro-fractures of micron-submicron (nano-) scale, including dissolution, filled and interlayer fractures. The existence of complex fracture-pore systems provides an effective pathway for primary migration and it also provides ample storage space for the residual petroleum in shale, which is important for the primary migration and storage for shale oil and gas resources.

Lower limits and grading evaluation criteria of tight oil source rocks of southern Songliao Basin, NE China

Abstract Taking the southern Songliao Basin as the target area, the hydrocarbon expulsion volume from source rocks has been quantitatively evaluated in this paper, based on the material balance method. Employing the “Overpressure” module of PetroMod software, the overpressure history of the source rocks was evaluated. According to the relationships between hydrocarbon expulsion rate, residual organic carbon content and overpressure within the source rocks, the lower limits of expulsion from tight oil source rocks were determined: a hydrocarbon expulsion amount of 2 mg/g, residual hydrocarbon content of 0.8%, and overpressure of 1 MPa. The source rocks with hydrocarbon expulsion amounts > 8 mg/g, a residual organic carbon content > 2.0%, and overpressure > 7 MPa were defined as excellent source rocks. As a result, tight oil source rocks can be divided into three types, excellent source rocks (type I), inefficient source rocks (type II) and non-productive source rocks (type III). The actual application in the southern Songliao Basin shows that the excellent source rocks have an obvious control on the planar and vertical distribution of tight oil discoveries, areas with excellent source rocks and nearby formations are favorable for the accumulation of tight oil.

Bulk Pyrolysis and Chemical Kinetic Characteristics of OM Related to the Occurrence of Immature-Low Mature Oils

Organic matters, such as resinite, suberinite, OM (organic matter) reworked by bacteria, sulphur-rich OM, which have close relationship to the occurrence and accumulation of immature-low mature oils, were pyrolyzed by the GHM and PY-GC for studying the hydrocarbon generation characteristics and the relationship between the special types of OMs and the occurrence of immature-low mature oil. Meantime, some reference OMs are studied in the same way. The experimental results indicate that the OMs related to the occurrence of immature-low mature oil can start to generate hydrocarbon obviously under a relative lower thermal stress, while the temperature required for hydrocarbon generation of reference OMs is relatively high. Furthermore, it shows that the generation of immature-low mature oil may be mostly a chemical reaction process. The chemical kinetic analyse shows that the OMs related to immature-low mature oils have lower activation energies than that of conventional OMs, although the occurrence and accumulation of immature oil are related to various geological conditions and factors. The preliminary application of the chemical kinetic model shows that the representative OMs related to the immature oils do start to generate a certain number of hydrocarbons in a shallower depth than that of hydrocarbon generation threshold for the conventional OMs.