Conglomerate Reservoir Pore Evolution Characteristics and Favorable Area Prediction: A Case Study of the Lower Triassic Baikouquan Formation in the Northwest Margin of the Junggar Basin, China

Xiao, Meng; Wu, Souheng; Yuan, Xuanjun; Xie, Zongrui

doi:10.1007/s12583-020-1083-6

Cited by 20 publications

(6 citation statements)

References 25 publications

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“…Exploration in the study area began in the 1980 s, and the Fengcheng Formation (P 1 f) of the Marbei slope (Pf) was located in the Xiazijie nosedive zone during both the Jurassic and Cretaceous orogenic periods, and present-day tectonics suggest that the area is still nosedive at present (Ma et al, 2022;Chen et al, 2022;Shi et al, 2022;Lu et al, 2023). The development of two large-scale retrograde fractures is the main through-origin fracture in this area, and the large-scale fractures are accompanied by microfractures around them (Xiao et al, 2021). Oil test in the well section of 4,831.0-4,886.0 m in the P 1 f 1 layer of the Permian Fengcheng Formation yielded 3.65 t of oil per day from a 4 mm nozzle and 1.48 m 3 of water per day; oil test in the well section of 4,683.0-4,701.0 m in the P 1 f 2 layer of the Permian Fengcheng Formation without fracturing yielded 0.54 t of oil per day from a 4 mm nozzle; oil test in the well section of 4,571.0-4,594.0 m in the P 1 f 3 layer of the Permian Fengcheng Formation, stratigraphic test, obtained 1.13 t of oil per day.…”

Section: Tectonic Location and Geologic Structurementioning

confidence: 99%

Fracturing parameter optimization technology for highly deviated wells in complex lithologic reservoirs

Hao,

Zhang,

Chen

et al. 2023

Front. Energy Res.

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Highly-deviated wells are the key technology to reduce the risk of drilling accidents and improve the utilization of reservoirs. However, for reservoirs with complex lithology, highly-deviated wells are faced with the problems of geomechanical transformation and fracturing parameter optimization. The research on fracturing parameter optimization technology of high-deviated wells in complex lithologic reservoirs is helpful to the research and application of geomechanics in deep unconventional reservoirs. This paper is based on geological mechanics laboratory experiments and logging interpretation, combined with regional geological background, to clarify the geological and mechanical characteristics of the Fengcheng Formation shale oil region in the Mabei Slope. On this basis, based on the current geostress field and natural fracture distribution pattern of the Mabei Slope, an integrated model of shale oil geological engineering in local well areas was established. Based on the finite element method, optimization design was carried out for the cluster spacing, construction fluid volume, displacement, and sand volume of highly deviated well fracturing, and three-dimensional simulation of fracturing fractures was completed. The research results indicate that: (1) The current dominant direction of the maximum principal stress in the Fengcheng Formation on the Mabei Slope is from northeast to southwest, with the maximum horizontal principal stress generally ranging from 90 to 120 MPa and the minimum horizontal principal stress generally ranging from 70 to 110 MPa. (2) The difference in stress between the two horizontal directions is relatively large, generally greater than 8 MPa. Two sets of natural fractures have developed in the research area, one with a northwest southeast trend and the other with a northeast southwest trend. The natural fracture density of the Fengcheng Formation shale reservoir in the Mabei Slope is 0.32–1.12/m, with an average of 0.58/m, indicating a moderate to high degree of fracture development. (3) The geological model and three-dimensional geo-mechanical model are established according to the actual drilling geological data, and different schemes are designed to carry out single parameter optimization. The optimization results show that the optimal cluster spacing of the subdividing cutting volume pressure of the highly deviated wells in the Fengcheng Formation of the Mabei Slope is 12 m, the optimal construction fluid volume is 1400–1600 m3/section, the optimal construction displacement is 8 m3/min, and the optimal sanding strength is 2.5 m3/m. At the same time, by comparing the fracturing implementation effect with the fracturing scheme design, it is proven that the artificial parameter optimization method for highly deviated wells based on the finite element method based on the regional stress background and the natural fracture development law proposed in this paper is feasible and can provide a scientific basis for the fracturing development of highly deviated wells in complex lithologic reservoirs. This research has been well applied in Mahu area of Xinjiang oilfield.

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Section: Tectonic Location and Geologic Structurementioning

confidence: 99%

Fracturing parameter optimization technology for highly deviated wells in complex lithologic reservoirs

Hao,

Zhang,

Chen

et al. 2023

Front. Energy Res.

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“…Among them, conglomerate oil reservoirs have attracted great attention because of their rich geological reserves and large development potential [ 3 , 4 , 5 , 6 ]. However, conglomerate reservoirs are a special kind of lithologic reservoir, and they still present problems worldwide due to their complex and variable lithology, the complex modal characteristics of pores, poor reservoir physical properties, and strong heterogeneity [ 7 , 8 , 9 , 10 ]. Water flooding is one of the common development methods for conglomerate reservoirs, but long-term water flooding can form a high permeability water-flow channel between injection and production wells during the high water cut period, which intensifies the heterogeneity of the reservoir, resulting in the inability to displace the remaining oil in the low permeability area, low water injection sweep coefficient, much remaining oil, and inefficient or ineffective injection water circulation [ 11 , 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

Optimization of Gel Flooding during the High Water Cut Stage in a Conglomerate Reservoir of the Xinjiang A Oilfield

Xin

Liu

et al. 2023

Polymers

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Influenced by water injection, a dominant flow channel is easily formed in the high water cut stage of a conglomerate reservoir, resulting in the inefficient or ineffective circulation of the injected water. With gel flooding as one of the effective development methods to solve the above problems, its parameter optimization determines its final development effect, which still faces great challenges. A new optimization method for gel flooding is proposed in this paper. Firstly, the gel flooding parameters were obtained through physical experiments; then, an experimental model of gel flooding was established according to the target reservoir, and parameter sensitivity analysis was carried out. Next, a history matching of the gel flooding experiment was carried out. Finally, history matching of the target reservoir was also carried out, and a gel flooding scheme was designed and optimized to determine the best parameters. The experimental results showed that the gelation time was 4 h and the gel viscosity was 6332 mPa·s; the breakthrough pressure, resistance factor (RF), and residual resistance factor (RRF) all decreased with the increase in permeability. The gel had a good profile control ability and improved oil recovery by 16.40%. The numerical simulation results illustrated that the porosity of the high permeability layer (HPL) had the greatest impact on the cumulative oil production (COP) of the HPL, and the maximum polymer adsorption value of the HPL had the largest influence on the COP of the low permeability layer (LPL) and the water cut of both layers. Benefiting from parameter sensitivity analysis, history matching of the gel flooding experiment and a conglomerate reservoir in the Xinjiang A Oilfield with less time consumed and good quality was obtained. The optimization results of gel flooding during the high water cut stage in a conglomerate reservoir of the Xinjiang A Oilfield were as follows: the gel injection volume, injection rate, and polymer concentration were 2000 m3, 50 m3/d, and 2500 mg/L, respectively. It was predicted that the water cut would decrease by 6.90% and the oil recovery would increase by 2.44% in two years. This paper not only provides a more scientific and efficient optimization method for gel flooding in conglomerate reservoirs but also has important significance for improving the oil recovery of conglomerate reservoirs.

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“…Organic-rich shales are crucial unconventional reservoirs for liquid and gaseous hydrocarbons . Large quantities of nanoscale pores , and micro/submillimeter-scale pores , occur in shales, providing appreciable storage space for free and adsorbed gas. , Pores in organic-rich shales are small and have poor connectivity. ,− The formation and evolution of pores are controlled by deposition/diagenesis of shales, organic matter maturation, and hydrocarbon generation/expulsion. − Compared to inorganic pores, organic pores have a more significant role for storing hydrocarbon gases in shale reservoirs. − The type, abundance, and maturity level of organic matter as well as the degree of oil cracking have important influences on the occurrence of organic pores in shales. ,,− Many studies have characterized pore structures of shale reservoirs with multiple techniques, including N 2 and CO 2 adsorption, mercury penetration, nano-CT, and SEM observation. ,,,− These works contribute significantly for shale gas exploration. However, it is difficult to quantitatively investigate organic and inorganic pores independently with respect to the total space and size of pores using conventional techniques. , For example, proportions of organic pores can be underestimated using the FE-SEM technique due to its limited spatial resolution and the inappropriate selection of the area of interest.…”

Section: Introductionmentioning

confidence: 99%

Organic Mesopore and Micropore Structures and Their Effects on Methane Adsorption in Marine Organic-Rich Shales

Guo

Zhao

et al. 2023

Energy Fuels

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Organic pores in organic-rich shale reservoirs can provide major pore space for adsorbed and free gas storage. In this study, the organic micropore and mesopore structures in organic-rich shale reservoirs and their influence on gas adsorption are investigated by comparing CO 2 , N 2 , and methane adsorption isotherms for organic matter-combusted and non-combusted organic-rich shale samples taken from the Wufeng− Longmaxi Formation in the Sichuan Basin. Experimental results show that organic pores in organic-rich shales from the Wufeng−Longmaxi Formation in Sichuan Basin are mainly smaller than 15 nm in diameters. Volumes of organic micropores and mesopores are mainly distributed in the diameter size ranges of 0.3−0.9 and 2−8 nm, respectively. Specific surface areas of organic micropores and mesopores are mainly distributed in the diameter size ranges of 0.3−0.7 and 2−4 nm, respectively. Organic pores dominate in the organic-rich shales from the Wufeng−Longmaxi Formation, contributing 49−77% and 50−84% of the entire micropore and mesopore volumes and specific surface areas, respectively. Organic micropores contribute 42− 84% and 44−85% of the entire micropore volume and specific surface area, respectively, and organic mesopores contribute 48−84% and 59−89% of the entire mesopore volume and specific surface area, respectively. Organic pores are dominant pore spaces for adsorbed methane in organic-rich shale reservoirs and contribute 75−87% of the total amount of adsorbed methane in shales from the Wufeng−Longmaxi Formation. Outcomes of this study demonstrate that organic matter combustion is a useful method for evaluating organic pores in organic-rich shales mainly according to following lines of evidence: (1) after combustion, samples have low volumes and specific surface areas for micropores and mesopores as well as extremely low contents of adsorbed methane. This suggests that combustion does not result in the generation of <15 nm inorganic micropores and mesopores in clay minerals to provide pore space for adsorbed methane. (2) The total organic carbon content (TOC) positively correlates with the organic pore volume and specific areas as well as the absolute amount of methane adsorption, suggesting that organic pores determined in this study are mainly controlled by TOC values and combustion caused the removal of organic micropores and mesopores.

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Conglomerate Reservoir Pore Evolution Characteristics and Favorable Area Prediction: A Case Study of the Lower Triassic Baikouquan Formation in the Northwest Margin of the Junggar Basin, China

Cited by 20 publications

References 25 publications

Fracturing parameter optimization technology for highly deviated wells in complex lithologic reservoirs

Fracturing parameter optimization technology for highly deviated wells in complex lithologic reservoirs

Optimization of Gel Flooding during the High Water Cut Stage in a Conglomerate Reservoir of the Xinjiang A Oilfield

Organic Mesopore and Micropore Structures and Their Effects on Methane Adsorption in Marine Organic-Rich Shales

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