scholarly journals Factors influencing gas well productivity in fractured tight sandstone reservoir

2021 ◽  
Author(s):  
Bin Zhao ◽  
Hui Zhang ◽  
Haiying Wang ◽  
Zhimin Wang
Keyword(s):  
Principal Stress ◽  
Maximum Principal Stress ◽  
Natural Fracture ◽  
Fracture Density ◽  
Tight Sandstone ◽  
Gas Well ◽  
Well Productivity ◽  
Factors Influencing ◽  
Sandstone Reservoir ◽  
Central Factors

AbstractThere are many factors which influence the absolute open flow potential (AOFP) of gas well. One of them is the angle between maximum principal stress direction and natural fracture strike in gas reservoir. In order to find out how the angle influences the AOFP of gas well. A lot of data related to gas well productivity of 14 wells located in gas reservoir T were collected and collated. Influential intensity of each factor on the AOFP before and after reservoir modification was investigated through grey relation analysis method. Results indicated that the AOFP of gas well before and after reservoir modification was governed by 10 factors. The five central factors influencing the initial AOFP are natural fracture density, porosity, permeability, elevation of geological top surface, and gas saturation, respectively. The five central factors influencing the AOFP of hydraulically fractured gas well are porosity, gas saturation, elevation of geological top surface, minimum principal stress, and permeability, respectively. Angle between maximum principal stress direction and natural fracture strike was not the central factor influencing gas well productivity. Reservoir modification can greatly improve gas well productivity in fractured tight sandstone reservoir. Natural fracture density was the strongest influencing factor of the initial AOFP. Minimum principal stress was one of the central factors influencing the AOFP of hydraulically fractured gas well. Research results can be used to guide well deployment and gas productivity investment projects of fractured tight sandstone reservoir.

Energy distribution of weak deformed rock mass and its influence on gas well productivity

2019 ◽  
Vol 7 (2) ◽  
pp. T423-T435 ◽  
Author(s):  
Shuai Yin ◽  
Yi Wang ◽  
Jingzhou Zhao ◽  
Yan Wang ◽  
Weitao Wu ◽  
...  
Keyword(s):  
Energy Density ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Production Capacity ◽  
Type I ◽  
Tight Sandstone ◽  
Tectonic Zone ◽  
Gas Well ◽  
Well Productivity ◽  
Low Amplitude

Microfractures represent an important rupture type, but current studies on the construction of microscale rupture parameters and their impacts on oil and gas production capacity are relatively weak. Therefore, we constructed the strain energy density ([Formula: see text]) based on 3D finite-element method (FEM) for the tight sandstone reservoir of the Permian He8 segment in the western region of the Sulige gas field, Ordos Basin. It indicated that the [Formula: see text] values of the major production layers are mainly distributed between 0.12 and [Formula: see text]. High-[Formula: see text]-value regions ([Formula: see text]) are mainly distributed in local areas of the western, central, and eastern regions. The [Formula: see text] values are small in the northwestern part of the study area and are usually less than [Formula: see text]. There is a very good exponential correlation between the [Formula: see text] values and gas well productivity (the main controlling factor for the production capacity of the He8 tight sandstone is the gas content, and fracturing, as an engineering factor affecting capacity, has not been taken into account). The distribution of the strain energy densities also matches the low-amplitude tectonic zone well. We have developed the criterion for the discrimination of gas well productivity using the strain energy density. According to this criterion, the conformity rates of type I, type II, and type III wells are 92.3%, 73.0%, and 83.3%, respectively. The areas with [Formula: see text] values greater than [Formula: see text], especially for areas with [Formula: see text] values exceeding [Formula: see text], which should serve as the core exploration targets. The research results can effectively guide tight gas sandstone exploration in low-amplitude tectonic zones and reduce the risk of drilling.

Fracturing Well Production Dynamic Simulation in Fractured Tight Sandstone Gas Reservoir

2013 ◽  
Vol 457-458 ◽  
pp. 410-415
Author(s):  
Chao Yang Xie ◽  
Yong Quan Hu ◽  
Xing Chen ◽  
Ying Chao Ma ◽  
Jin Zhou Zhao ◽  
...  
Keyword(s):  
Flow Coefficient ◽  
Production Performance ◽  
Natural Fracture ◽  
Inverse Transformation ◽  
Hydraulic Fractures ◽  
Fractured Reservoir ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Sandstone Reservoir ◽  
Effective Development

The tight sandstone formation usually has natural fracture, which is the foundation of effective development using hydraulic fracturing. The conventional reservoir productivity simulation method don't adapt to it. In this paper, Warren & Root model was used for describing infinity tight fractured reservoir model with vertical hydraulic fractures. Then, assuming the fracture length and the width does not vary with time and formation pressure, fracture seepage equation was obtained in base of the one-dimensional flow Darcy percolation equation and continuity equation. By Stehfese, a method of numerical inverse transformation, production performance simulation model was established for natural fractured tight sandstone reservoir. Taking for actual example from Daqing oilfield, affection of characteristics of natural fractures and artificial fracture parameters on productivity of natural fractured tight sandstone reservoir were analyzed. Elastic storability ratio has a greater influence than interporosity flow coefficient. It was the core technique for the gas reservoir to effective development by large amount of fluid and low sand ratio.

scholarly journals Investigation of the Effect of Natural Fractures on Multiple Shale-Gas Well Performance Using Non-Intrusive EDFM Technology

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 932 ◽  
Author(s):  
Wei Yu ◽  
Xiaohu Hu ◽  
Malin Liu ◽  
Weihong Wang
Keyword(s):  
Shale Gas ◽  
History Matching ◽  
Natural Fracture ◽  
Fracture Density ◽  
Natural Fractures ◽  
Well Performance ◽  
Two Phase ◽  
Gas Well ◽  
Discrete Fracture Model ◽  
Well Spacing

The influence of complex natural fractures on multiple shale-gas well performance with varying well spacing is poorly understood. It is difficult to apply the traditional local grid refinement with structured or unstructured gridding techniques to accurately and efficiently handle complex natural fractures. In this study, we introduced a powerful non-intrusive embedded discrete fracture model (EDFM) technology to overcome the limitations of exiting methods. Through this unique technology, complex fracture configurations can be easily and explicitly embedded into structured matrix blocks. We set up a field-scale two-phase reservoir model to history match field production data and predict long-term recovery from Marcellus. The effective fracture properties were determined thorough history matching. In addition, we extended the single-well model to include two horizontal wells with and without including natural fractures. The effects of different numbers of natural fractures on two-well performance with varying well spacing of 200 m, 300 m, and 400 m were examined. The simulation results illustrate that gas productivity almost linearly increases with the number of two-set natural fractures. Furthermore, the difference of well performance between different well spacing increases with an increase in natural fracture density. A larger well spacing is preferred for economically developing the shale-gas reservoirs with a larger natural fracture density. The findings of this study provide key insights into understanding the effect of natural fractures on well performance and well spacing optimization.

scholarly journals A reservoir quality evaluation approach for tight sandstone reservoirs based on the gray correlation algorithm: A case study of the Chang 6 layer in the W area of the as oilfield, Ordos Basin

2021 ◽  
pp. 014459872199851
Author(s):  
Yuyang Liu ◽  
Xiaowei Zhang ◽  
Junfeng Shi ◽  
Wei Guo ◽  
Lixia Kang ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
Comprehensive Evaluation ◽  
Ordos Basin ◽  
Reservoir Quality ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Evaluation Approach ◽  
Correlation Algorithm ◽  
Gray Correlation ◽  
Sandstone Reservoir

As an important type of unconventional hydrocarbon, tight sandstone oil has great present and future resource potential. Reservoir quality evaluation is the basis of tight sandstone oil development. A comprehensive evaluation approach based on the gray correlation algorithm is established to effectively assess tight sandstone reservoir quality. Seven tight sandstone samples from the Chang 6 reservoir in the W area of the AS oilfield in the Ordos Basin are employed. First, the petrological and physical characteristics of the study area reservoir are briefly discussed through thin section observations, electron microscopy analysis, core physical property tests, and whole-rock and clay mineral content experiments. Second, the pore type, throat type and pore and throat combination characteristics are described from casting thin sections and scanning electron microscopy. Third, high-pressure mercury injection and nitrogen adsorption experiments are optimized to evaluate the characteristic parameters of pore throat distribution, micro- and nanopore throat frequency, permeability contribution and volume continuous distribution characteristics to quantitatively characterize the reservoir micro- and nanopores and throats. Then, the effective pore throat frequency specific gravity parameter of movable oil and the irreducible oil pore throat volume specific gravity parameter are introduced and combined with the reservoir physical properties, multipoint Brunauer-Emmett-Teller (BET) specific surface area, displacement pressure, maximum mercury saturation and mercury withdrawal efficiency parameters as the basic parameters for evaluation of tight sandstone reservoir quality. Finally, the weight coefficient of each parameter is calculated by the gray correlation method, and a reservoir comprehensive evaluation indicator (RCEI) is designed. The results show that the study area is dominated by types II and III tight sandstone reservoirs. In addition, the research method in this paper can be further extended to the evaluation of shale gas and other unconventional reservoirs after appropriate modification.

scholarly journals Elastic Simulation of Joints with Particle-Based Fluid

2021 ◽  
Vol 11 (15) ◽  
pp. 6900
Author(s):  
Su-Kyung Sung ◽  
Sang-Won Han ◽  
Byeong-Seok Shin
Keyword(s):  
Principal Stress ◽  
Human Body ◽  
Yield Condition ◽  
Maximum Principal Stress ◽  
Human Motion ◽  
The Difference ◽  
The Moment ◽  
External Forces ◽  
Physical Changes ◽  
Elastic Simulation

Skinning, which is used in skeletal simulations to express the human body, has been weighted between bones to enable muscle-like motions. Weighting is not a form of calculating the pressure and density of muscle fibers in the human body. Therefore, it is not possible to express physical changes when external forces are applied. To express a similar behavior, an animator arbitrarily customizes the weight values. In this study, we apply the kernel and pressure-dependent density variations used in particle-based fluid simulations to skinning simulations. As a result, surface tension and elasticity between particles are applied to muscles, indicating realistic human motion. We also propose a tension yield condition that reflects Tresca’s yield condition, which can be easily approximated using the difference between the maximum and minimum values of the principal stress to simulate the tension limit of the muscle fiber. The density received by particles in the kernel is assumed to be the principal stress. The difference is calculated by approximating the moment of greatest force to the maximum principal stress and the moment of least force to the minimum principal stress. When the density of a particle increases beyond the yield condition, the object is no longer subjected to force. As a result, one can express realistic muscles.

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