Lijun Mu, Xiaojia Xue, Jie Bai^*, Xiaoyan Li, Xueliang Han

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1365-1379, 2024, DOI:10.32604/fdmp.2024.049013

Abstract Following large-scale volume fracturing in shale oil reservoirs, well shut-in measures are generally employed. Laboratory tests and field trials have underscored the efficacy of fracturing fluid imbibition during the shut-in phase in augmenting shale oil productivity. Unlike conventional reservoirs, shale oil reservoirs exhibit characteristics such as low porosity, low permeability, and rich content of organic matter and clay minerals. Notably, the osmotic pressure effects occurring between high-salinity formation water and low-salinity fracturing fluids are significant. The current understanding of the mobilization patterns of crude oil in micro-pores during the imbibition process remains nebulous, and the… More >

Huiyan Zhao¹, Xuezhong Chen¹, Zhijian Hu^2,*, Man Chen¹, Bo Xiong³, Jianying Yang¹

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1313-1330, 2024, DOI:10.32604/fdmp.2024.048840

Abstract Using the typical characteristics of multi-layered marine and continental transitional gas reservoirs as a basis, a model is developed to predict the related well production rate. This model relies on the fractal theory of tortuous capillary bundles and can take into account multiple gas flow mechanisms at the micrometer and nanometer scales, as well as the flow characteristics in different types of thin layers (tight sandstone gas, shale gas, and coalbed gas). Moreover, a source-sink function concept and a pressure drop superposition principle are utilized to introduce a coupled flow model in the reservoir. A… More > Graphic Abstract

Hui Tian¹, Dandan Zhao¹, Yannan Wu^2,3,*, Xingyu Yi¹, Jun Ma¹, Xiang Zhou⁴

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1265-1277, 2024, DOI:10.32604/fdmp.2023.044833

Abstract The low porosity and low permeability of tight oil reservoirs call for improvements in the current technologies for oil recovery. Traditional chemical solutions with large molecular size cannot effectively flow through the nano-pores of the reservoir. In this study, the feasibility of Nanofluids has been investigated using a high pressure high temperature core-holder and nuclear magnetic resonance (NMR). The results of the experiments indicate that the specified Nanofluids can enhance the tight oil recovery significantly. The water and oil relative permeability curve shifts to the high water saturation side after Nanofluid flooding, thereby demonstrating an More > Graphic Abstract

Yan Liu¹, Tianli Sun², Bencheng Wang^1,*, Yan Feng²

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.6, pp. 1165-1180, 2024, DOI:10.32604/fdmp.2023.041852

Abstract A numerical model of hydraulic fracture propagation is introduced for a representative reservoir (Yuanba continental tight sandstone gas reservoir in Northeast Sichuan). Different parameters are considered, i.e., the interlayer stress difference, the fracturing discharge rate and the fracturing fluid viscosity. The results show that these factors affect the gas and water production by influencing the fracture size. The interlayer stress difference can effectively control the fracture height. The greater the stress difference, the smaller the dimensionless reconstruction volume of the reservoir, while the flowback rate and gas production are lower. A large displacement fracturing construction More >

Sichen Li^1,2, Dehua Liu^1,2,*, Liang Cheng^1,2, Pan Ma^1,2

Energy Engineering, Vol.121, No.7, pp. 1921-1943, 2024, DOI:10.32604/ee.2024.049906

Abstract Due to the depletion of conventional energy reserves, there has been a global shift towards non-conventional energy sources. Shale oil and gas have emerged as key alternatives. These resources have dense and heterogeneous reservoirs, which require hydraulic fracturing to extract. This process depends on identifying optimal fracturing layers, also known as ‘sweet spots’. However, there is currently no uniform standard for locating these sweet spots. This paper presents a new model for evaluating fracturability that aims to address the current gap in the field. The model utilizes a hierarchical analysis approach and a mutation model, More > Graphic Abstract

Jianchao Shi^1,2, Yanan Zhang³, Wantao Liu^1,2, Yuliang Su^3,*, Jian Shi^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.5, pp. 1147-1163, 2024, DOI:10.32604/fdmp.2023.044500

Abstract Class III tight oil reservoirs have low porosity and permeability, which are often responsible for low production rates and limited recovery. Extensive repeated fracturing is a well-known technique to fix some of these issues. With such methods, existing fractures are refractured, and/or new fractures are created to facilitate communication with natural fractures. This study explored how different refracturing methods affect horizontal well fracture networks, with a special focus on morphology and related fluid flow changes. In particular, the study relied on the unconventional fracture model (UFM). The evolution of fracture morphology and flow field after More >

Fang Li^1,*, Juan Wu¹, Haiyong Yi², Lihong Wu², Lingyun Du¹, Yuan Zeng¹

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.5, pp. 1015-1030, 2024, DOI:10.32604/fdmp.2023.043256

Abstract Methods for horizontal well spacing calculation in tight gas reservoirs are still adversely affected by the complexity of related control factors, such as strong reservoir heterogeneity and seepage mechanisms. In this study, the stress sensitivity and threshold pressure gradient of various types of reservoirs are quantitatively evaluated through reservoir seepage experiments. On the basis of these experiments, a numerical simulation model (based on the special seepage mechanism) and an inverse dynamic reserve algorithm (with different equivalent drainage areas) were developed. The well spacing ranges of Classes I, II, and III wells in the Q gas More > Graphic Abstract

Lian Liu^1,2, Liang Li^1,2, Kebo Jiao^1,2,*, Junwei Fang^1,2, Yun Luo^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.5, pp. 975-987, 2024, DOI:10.32604/fdmp.2023.030109

Abstract Ultra-deep reservoirs play an important role at present in fossil energy exploitation. Due to the related high temperature, high pressure, and high formation fracture pressure, however, methods for oil well stimulation do not produce satisfactory results when conventional fracturing fluids with a low pumping rate are used. In response to the above problem, a fracturing fluid with a density of 1.2~1.4 g/cm was developed by using Potassium formatted, hydroxypropyl guanidine gum and zirconium crosslinking agents. The fracturing fluid was tested and its ability to maintain a viscosity of 100 mPa.s over more than 60 min More >

Zhengrong Chen^*, Mao Jiang, Chuanzhi Ai, Jianshu Wu, Xin Xie

Energy Engineering, Vol.121, No.6, pp. 1657-1669, 2024, DOI:10.32604/ee.2024.030222

Abstract Based on the actual data collected from the tight sandstone development zone, correlation analysis using the Spearman method was conducted to determine the main factors influencing the gas production rate of tight sandstone fracturing. An integrated model combining geological engineering and numerical simulation of fracture propagation and production was completed. Based on data analysis, the hydraulic fracture parameters were optimized to develop a differentiated fracturing treatment adjustment plan. The results indicate that the influence of geological and engineering factors in the X1 and X2 development zones in the study area differs significantly. Therefore, it is… More >

Xingliang Deng¹, Peng Cao^2,*, Yintao Zhang¹, Yuhui Zhou³, Xiao Luo¹, Liang Wang³

Energy Engineering, Vol.121, No.5, pp. 1195-1207, 2024, DOI:10.32604/ee.2023.045870

Abstract The fractured-vuggy carbonate oil resources in the western basin of China are extremely rich. The connectivity of carbonate reservoirs is complex, and there is still a lack of clear understanding of the development and topological structure of the pore space in fractured-vuggy reservoirs. Thus, effective prediction of fractured-vuggy reservoirs is difficult. In view of this, this work employs adaptive point cloud technology to reproduce the shape and capture the characteristics of a fractured-vuggy reservoir. To identify the complex connectivity among pores, fractures, and vugs, a simplified one-dimensional connectivity model is established by using the meshless More >