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Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Chang-6 reservoir in the Yanchang formation in Xingzichuan area is characteristic of low oil saturation, strong oil wetting and strong heterogeneity (permeability = 0.10 – 1.0 mD). In fracturing operations in this area, it was found that the conventional fracturing fluids have weak wettability alteration ability and poor imbibition displacement effect. To efficiently develop this reservoir, it is imperative to use a fracturing fluid with the ability of production enhancement by imbibition. Using NMR T2 spectrum, chemicals of different compositions were tested for their ability to produce the crude oils stored in the micrometernanometer sized pores in the Chang-6 reservoir, and the factors affecting fracturing fluids’ in-situ displacement of crude oil as well as the imbibition mechanism of the in-situ displacement are investigated. The results of the study show that compared with other agents, AX-2, a negatively charged ionic surfactant agent, is more suitable for producing the low oil saturation Chang-6 reservoir. Using 0.10% of AX-2, the imbibition recovery of oil is greater than 30%, and the percent oil produced from the small nanometer-sized pores is 42.08%, while that from the large micrometer-sized pores is 22.62%. If AX-2 is used to formulate a 10-nanometer nanoemulsion AX-1, it has stronger anti-adsorption ability and better performance in producing the oil from the Chang-6 reservoir; the percent oil produced from the nanometer pores is increased to 58.26%, while that from the micrometer pores is increased to 29.7%. An AX-1 emulsion with surface tension of 1.5 mN/m is the best emulsion for producing the Chang-6 reservoir, since this emulsion has higher imbibition force and crude oil stripping capacity. The fracturing fluid optimized with the AX-1 emulsion is used in field fracturing operations, and good results were obtained, the average daily production rate of crude oil reached 26 tons. [ABSTRACT FROM AUTHOR]

Copyright of Drilling Fluid & Completion Fluid is the property of Drilling Fluid & Completion Fluid Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Surfactants are usually added to the fracturing fluids to enhance the imbibition between fractures and matrix, which is an important measure to improve oil recovery. The popular perspective believes that altering water-wet conditions and keeping a relatively high IFT value are the keys to achieving the imbibition process. Recently, both indoor experiments and oilfield practice have shown that the surfactant systems with ultra-low IFT can also achieve imbibition and effectively recover oil from the matrix. For the problem that the imbibition mechanism of ultra-low IFT system is still unclear, the wettability alteration system, ultra-low IFT system, and emulsification system are constructed, the characteristics of imbibition systems and imbibition recovery are clarified, the oil-water transport patterns and dominant mechanisms of wettability alteration system and ultra-low IFT system with excellent emulsification are revealed by using mathematical models. The results show that the applicability range of the wettability alteration system and ultra-low IFT system with excellent emulsification is different. The wettability alteration system has better imbibition effects under 0.1 mD, but the ultra-low IFT system with excellent emulsification performs better under 0.01 mD and 0.001 mD. The imbibition process of the wettability alteration system is a layer flow pattern dominated by capillary force, the rate at which the wetted phase fills the pores decreases rapidly with the decrease of permeability, and the imbibition recovery decreases significantly from about 45% to 18%. The micro-nano emulsions can be formed by the ultra-low IFT system with excellent emulsification, which has a special emulsification and diffusion mechanism. In the early stage, oil is mainly recovered by emulsification and diffusion, in the late stage, the layer flow pattern of IFT reduction and wettability alteration gradually works, and the imbibition recovery decreases from about 38% to 23%. The emulsification and diffusion mechanism of the ultra-low IFT system with excellent emulsification is suitable for the imbibition of tighter reservoirs, and has a broad application in fracturing and stimulation of tight reservoirs. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Science Technology & Engineering is the property of Chinese Society of Technology Economics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Drilling Fluid & Completion Fluid is the property of Drilling Fluid & Completion Fluid Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Drilling Fluid & Completion Fluid is the property of Drilling Fluid & Completion Fluid Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In coal mining, the upper top plate is hard to fracture, and it is easy to form large overhanging structures, which can induce serious rock burst and other hazards. Therefore, that is not conducive to safe and efficient mine production. Aiming at the engineering question of the overhanging roof on coal seam by the hydraulic fracturing, intergrated geological engneering simulation technology was adopted, considering the longitudinal stratification properties of rock layers, a fine-grained model for multi-cluster fracturing of large scale horizontal well sections was developed, and research on the mechanical mechanism and optimization of construction parameters for hydraulic fracturing to cut thick coal seam roofs was carried out. The study shows these as follows. Multi-stage fracturing of horizontal wells can adequately cut the upper topsides and produce a closely cut slit network structure, additional induced stress value increased by 10%, thus overhead pressure relief problems can be solved in efficient. The fracture volume formed by the high viscosity slick water+cross-linked freeze gel fracturing fluid system is approximately 40% higher than that of the low viscosity slick water system. Fracutring fluid types, formation properties, fluid volume, displacement volume and segment length are the mian controlling factors affecting the fracture propagation in the order from strong to weak. Geological modelling-fracture propagation-stress calculation was combined in this paper, depth of the scale of hydraulic fracture propagation and the extent of its weakening modification of the thick top layer was studied as well as, the results could be instructive in the development of coal seams containing thick seam tops in safe and efficient, the results could guide the development of coal seams containing thick seam tops in safe and efficient. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Having the characters of large reserve, serious heterogeneity, and deep buried, carbonate reservoirs are widely distributed in China, and the treatment effect using traditional acid fluid system is not very good. Viscoelastic surfactant-based self-diverting acid treatment is a novel and high efficient stimulating technique which has been developed in recent years. Corrosion inhibitor is the important guarantee for successful implementation of the acidizing technology. Viscoelastic surfactant has an interaction with conventional hydrochloric acid corrosion inhibitor, and the interaction can affect the corrosion control effect. Low temperature corrosion inhibitors have been developed for some time, but high temperature corrosion inhibitors are still in research and development. Using good water-soluble corrosion inhibitor in viscoelastic surfactant-based self-diverting acid is the future research direction. [ABSTRACT FROM AUTHOR]