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In order to ensure that the new block can select the best displacement method, this paper determines 23 key reservoir basic parameters based on the statistical analysis of the field application of the tertiary oil recovery displacement method in typical blocks at home and abroad. The best displacement method is selected by the fuzzy evaluation method, and the correlation degree between the target block and the typical block is calculated by the improved Deng correlation method; then, the ultimate recovery rate of the target block is determined. Taking a new block of an oil field in China as an example, the optimal displacement method of three typical blocks of polymer flooding, burning oil layer flooding, and ternary composite flooding is selected by the fuzzy evaluation method; then, the improved Deng correlation method calculates that the final recovery rate of the new block using burning oil layer flooding is the tallest, and the burning oil layer flooding is selected the best way to replace the block. Based on this, the optimal results of displacement method are analyzed when porosity and air permeability of the new block reservoir are changed. The method proposed in this paper provides a calculation basis for the optimization of displacement method of the new blocks. [ABSTRACT FROM AUTHOR]

Member 1 of the Cretaceous Qingshankou Formation (K2qn1 Member) in the Southern Songliao Basin, composed of mainly semi-deep and deep lacustrine shale layers, is rich in shale oil. Previous studies on shale reservoir characteristics mainly focused on marine shale strata, but few studies have considered lacustrine shale strata, so the pore-throat features and differences between the lacustrine shale reservoir and marine shale reservoir need to be studied. Taking the Class-I and II sweet spot sections and Class-III non-sweet spot section of Da'an shale oil demonstration area as examples, SEM (scanning electron microscopy) was used to qualitatively and semi-quantitatively describe the morphology and occurrence characteristics of the shale. Full-scale pore size distributions of lacustrine shale samples were quantitatively measured by N2GA (nitrogen absorption) combined with dominant pore size segments tested by experiments. Finally, the lacustrine shale reservoir was compared with classical marine shale reservoirs, and factors influencing semi-deep lacustrine and deep lacustrine shale oil in a large depression basin were analyzed by XRD (X-ray diffraction). The results show that Class-I and II sweet spots are rich in organic matter, quartz, and carbonate minerals, have mainly type H2 nitrogen adsorption hysteresis loops, and contain mainly inorganic pores, such as intergranular and intragranular pores in nano-scale, forming nano-scale reservoirs. Lacustrine shale is obviously different from marine shale in terms of pore structure, and the development characteristics of the lacustrine shale pore structure are more influenced by mineral components. Factors affecting the development of shale oil reservoirs in K2qn1 member include mineral components, TOC (total organic carbon), and diagenetic processes. Quartz and carbonate minerals are good for enhancing reservoir quality, while clay minerals are destructive to the development of reservoirs. TOC is the material foundation and main factor for forming organic pores, but the higher the TOC, the smaller the diameter of the organic pores will be. Compaction, cementation, and dissolution are the main diagenetic processes controlling the development of reservoir space. [ABSTRACT FROM AUTHOR]

For the past fifty years, the northern Songliao Basin in China was thought to contain Lower Cretaceous coal-measure and gas-generating shale. Oil-type shales did not receive much attention until oil exploration activities made a breakthrough in the Southern Shuangcheng (SSC) depression. In this study, the geochemical characteristics of the newly discovered K 1 yc 4 (fourth member of the Lower Cretaceous YingCheng Formation) oil-type shale in the SSC depression were analyzed, including the organic matter abundance, organic matter type, thermal maturity, hydrocarbon potential, and sedimentary environment. A total of 393 core samples were collected, and Rock-Eval pyrolysis, gas chromatography-mass spectrometry (GC-MS), organic petrography, carbon isotope analysis, and constant and trace element analyses were conducted. The K 1 yc 4 shale was determined to have a good to excellent hydrocarbon potential with high TOC values (mostly 2.0–4.0%). The organic matter was mainly from lower hydrobiont, algae, bacteria, and lesser amounts of terrestrial plants. The organic matter is mainly type I to type II based on the hydrogen index (HI) (average HI = 193.36 mg HC/g TOC), the carbon isotopes of the kerogen (mostly −26 to −30‰), and the organic petrography (average sapropelinite + liptinite of 55.0 vol%). The maturity parameters, i.e., T max (mean 452 °C) and vitrinite reflectance (0.8–1.1%), suggest that the shale is in the mature thermal evolution stage. The shale's maximum hydrocarbon-generating intensity is up to 713.29 × 104/km2, and its hydrocarbon-expelling intensity is stable at 116.63 × 104/km2. The constant and trace element analyses (Sr, Ba, V, Ni, Cr, Ti) revealed that the organic matter deposition and preservation occurred in a fresh-brackish and dysoxic-anoxic water environment. Volcanic eruptions probably played a vital role in the enrichment of the organic matter in the oil-type shale. In addition, the results of this study provide evidence that the Lower Cretaceous strata in the northern Songliao Basin meet the geological conditions of oil-prone shale, which expands the petroleum exploration horizon in this region. • The oil-type shales in the Lower Cretaceous of northern Songliao Basin, China have been studied for the first time. • Their geochemical characteristics, geologic origin, and hydrocarbon potential were clarified. • Volcanic eruption played an important role in their formation. [ABSTRACT FROM AUTHOR]

Based on a large number of empirical statistics of tertiary oil recovery technology in China, including polymer flooding, chemical flooding, gas flooding, in situ combustion, steam flooding, ect., 22 key reservoir parameters were filterized. Five levels of quantitative screening criteria were developed for different tertiary oil recovery methods. The mean algorithm for the downward approximation and the grey correlation theory were used in this paper to quickly select the appropriate tertiary oil recovery method for the target blocks, which provides a preferred development method for subsequent potential evaluation. In the rapid analogy evaluation method of tertiary oil recovery potential, the total similarity ratio between the target block and the example block is determined. The target block is matched with the appropriate instance block according to the total similarity ratio value, using 80% as the boundary. The ratio of the geological reserves is used to predict the oil recovery interval, the actual annual injection data, and the economic profit, thus quickly predicting the economic potential of the tertiary oil recovery technology in the target block. Currently, our research team has integrated these two methods into the tertiary oil production potential evaluation software EORSYS3.0. The empirical analysis shows that this method is reasonable and the conclusion is reliable. In addition, the actual enhanced recovery value is within the effective range predicted by the method. The method and results of this paper will provide an important decision-making reference for the application and sustainable development of China Petroleum's main tertiary oil recovery technology in the next 5–10 years. [ABSTRACT FROM AUTHOR]

In view of the water swelling of mudstone and the creep induction function of formations in the process of oilfield water injection, the casing incurs collapse deformation under local lateral load. In this study, according to the actual collapse deformation characteristics of the casing in the second section of the Qing formation of the Songliao Basin in China, the yield surfaces of the casing collapse deformation are considered as plane plastic areas (half rhombus) with symmetric parabola shaped boundaries, and a mechanical model for the local lateral collapse deformation of casing is presented based on the principle of virtual work. Four types of casing, 4½″J55, 5½″J55, 4½″N80 and 5½″N80, are selected as examples. The relation of the casing intensity, the absolute reduction of intensity and the relative reduction ratio of intensity change with casing wall thickness, yield stress, radial maximum deformation, and deformation length are calculated and analyzed. The results show that the casing intensity of the casing is reduced under local lateral load, which is lower than the design standard value of the American Petroleum Association specification (API SPEC) 5CT. The relative reduction ratio declines linearly with the wall thickness of the casing wall as the yield stress increases, and increases linearly with increasing maximum deformation. In addition, the local lateral bearing capacity of the casing reaches the minimum value when the plastic deformation length reaches the critical value or the deformation quantity is less than the critical value. The conclusions provide scientific guidance for preventing casing failure accidents caused by deformation. [ABSTRACT FROM AUTHOR]

The Middle Permian Lucaogou Formation in the Santanghu Basin (northwest China) develops one of the thickest salinized lacustrine organic-rich shale (SLORS) in the world. The SLORS has been proven as sources for crude oil and tight oil, as well as sources and reservoirs for shale oil in the basin. A total of 52 SLORS samples were collected from the second member of Lucaogou Formation (P 2 l2), and analyzed by mineralogy and element geochemistry, in order to reveal the paleoenvironment, provenance, tectonic setting and shale oil potential. The results imply an evolution of paleoenvironment from anoxic, saline to dysoxic-oxic, freshwater lake, which is caused by an increased freshwater influx. Early in the P 2 l2, volcanic ash and hydrothermal fluids have increased the nutrient level in the lake and therefore elevated the bioproductivity. The P 2 l2 SLORS is originated from intermediate volcanic rocks, accompanied by minor proportions of basic volcanic rocks. The parent rocks of P 2 l2 SLORS have experienced weak degree of chemical weathering, and probably derived from a continental island arc setting. Micro-, nano-pores (inter-grain pores, inter-crystalline pores, dissolution pores and organic matter pores) and microfractures are widely observed in the P 2 l2 SLORS, which provides sufficient storage space for hydrocarbons. The P 2 l2 SLORS is dominated by carbonate minerals, quartz and feldspar, which are all brittle minerals and favourable for artificial fracturing. Comprehensive study indicates that the upper P 2 l2 SLORS hosts a better shale oil potential, due to the relatively high TOC, abundant micropores and microfractures, and high brittle mineral contents. In addition, individual element geochemical parameters in the Santanghu Basin should be used with caution, for example, the paleoredox proxy U/Th and paleosalinity proxy Sr/Ba are also influenced by volcanic and hydrothermal activity. This implies that a multi-proxy analysis should be applied during the study of paleoenvironmental conditions. • Paleoenvironment of the P 2 l2 organic-rich shale was reconstructed. • Provenance and tectonic setting of the P 2 l2 organic-rich shale were indicated. • Shale oil potential of the P 2 l2 organic-rich shale was comprehensively evaluated. • Suggestions for further shale oil exploration and exploitation were proposed. [ABSTRACT FROM AUTHOR]