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Recently, petroleum exploration of the Dongpu depression has become increasingly difficult, primarily because of the unclear potential and distribution of deep strata resources (specifically, the Shahejie 3 formation). A pyrolysis experiment and hydrocarbon generation kinetics can provide important parameters for hydrocarbon generation history and resource reevaluation. Therefore, four samples of the Dongpu depression were selected for a kerogen pyrolysis experiment, and the software KINETICS 2000 was used to calculate the pre-exponential factors (A) of different components and the activation energies (E) of the reactants to further establish the kinetic parameters of different kerogens in the Dongpu depression. The hydrocarbon generation history of the sample was determined using the software BasinMod 1D based on thermal and burial histories, and the hydrocarbon generation characteristics of different sags and different types of kerogen were studied. The results show that the hydrocarbon generation potential in the northern Dongpu depression is stronger than that in the south. Moreover, the activation energy (E) distribution of type I kerogen (Well W146) is widest, followed by type II 1 (Well C9) and type II 2 kerogens (Well H88); and type III kerogen (Well X8) is the most concentrated. Moreover, the potential for hydrocarbon generation in the Qianliyuan the Haitongji−Liutun areas is high.

Numerous large gas fields with large proven reserves occur in the deep formations of Songliao Basin, NE China. However, some challenges remain as follows: (1) the main source rock is poorly studied and (2) the origins and genetic types of the natural gases are controversial. In this study, these problems can be addressed by the research of the paleoenvironments during shale deposition, the organic matter sources, the source rock potential, the gas origin and genetic type, and gas–source correlations. The redox conditions of the water column during the Huoshiling to Yingcheng depositions were transitional (suboxidizing to subreducing) environments, and the Huoshiling deposition corresponded to reducing conditions. The paleosalinity of water was brackish to fresh from Huoshiling to Yingcheng depositions. The organic matters of the Huoshiling–Yingcheng shales mainly originated from terrigenous and/or lacustrine materials. The shales are evaluated as the fair to good source rock potential, and the Huoshiling is the best. The gases in the Huoshiling and Shahezi were mainly organic and thermogenic origins, with some inorganic origins. The gases of organic origins are mainly the mixed sources of coal-derived and oil-associated gases and are predominant products of secondary cracking, suggesting the well gas exploration potential in deep formations of Songliao Basin. The gases in the Shahezi formation are predominantly sourced by the Shahezi shales, indicating an approaching-source accumulation.

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Numerical simulations have often been used in close-distance coal seam studies. However, numerical simulations can contain certain subjective and objective limitations, such as high randomness and excessively simplified models. In this study, close-distance coal seams were mechanically modeled based on the half-plane theory. An analytical solution of the floor stress distribution was derived and visualized using Mathematica software. The principal stress difference was regarded as a stability criterion for the rock surrounding the roadway. Then, the evolution laws of the floor principal stress difference under different factors that influence stability were further examined. Finally, stability control measures for the rock surrounding the roadway in the lower coal seam were proposed. The results indicated the following: (1) The principal stress difference of the floor considers the centerline of the upper coal pillar as a symmetry axis and transmits radially downward. The principal stress difference in the rock surrounding the roadway gradually decreases as the distance from the upper coal pillar increases and can be ranked in the following order: left rib > roof > right rib. (2) The minimum principal stress difference zones are located at the center of the left and right “spirals,” which are obliquely below the edge of the upper coal pillar. This is an ideal position for the lower coal seam roadway. (3) The shallowness of the roadway, a small stress concentration coefficient, high level of coal cohesion, large coal internal friction angle, and appropriate lengthening of the working face of the upper coal seam are conducive to the stability of the lower coal seam roadway. (4) Through bolt (cable) support, borehole pressure relief, and pregrouting measures, the roof-to-floor and rib-to-rib convergence of the 13313 return airway is significantly reduced, and the stability of the rock surrounding the roadway is substantially improved. This research provides a theoretical basis and field experience for stabilizing the lower coal seam roadways in close-distance coal seams.

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