scholarly journals Research on the Percolation Mechanism of Perturbation Under Simultaneous Fracturing in Shale Reservoirs

2021 ◽  
Vol 9 ◽  
Author(s):  
Jie He ◽  
Xiaobing Niu ◽  
Qingchun Meng ◽  
Fajun Guo ◽  
Hongmei Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Orthogonal Experiment ◽  
Cross Flow ◽  
Flow Coefficient ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Horizontal Section ◽  
Lower Productivity ◽  
Engineering Parameters

Compared with conventional reservoirs, shale gas reservoirs usually have no natural productivity or lower productivity, and the rate of production decline is high in the later stage. The production of shale gas can be effectively improved by designing reasonably or fracturing. Therefore, it is critical for shale gas reservoir to study how to design proper parameters to make it effectively developed. Based on data of block-A region of the Zhejiang gas field, considering the contribution of rock compression to the production, the productivity formula of horizontal well at different seepage stages is deduced. Data from block-A are verified by orthogonal experiment, including gas reservoir parameters and engineering parameters. The results show that the order of reservoir parameters that affect the development of shale gas is as follows: Langmuir pressure, diffusion coefficient, cross flow coefficient, and Langmuir volume; the order of engineering parameters that affect the development of shale gas is as follows: number of fractures, horizontal section length, production pressure, fractures length, row spacing, and well spacing. The research results have been applied to the Zhejiang gas field. The initial rate of decline after adjustment is reduced by 26.08% and production increases by 17.06% after stabilization compared to wells without adjustment parameters. The research has important reference significance for the efficient development of similar gas reservoirs.

scholarly journals Development of a prmA genes quantification technique and assessment of the technique’s application potential for oil and gas reservoir exploration

2018 ◽  
Vol 36 (5) ◽  
pp. 1172-1188 ◽  
Author(s):  
Zhuo Ning ◽  
Ze He ◽  
Sheng Zhang ◽  
Miying Yin ◽  
Yaci Liu ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Quantitative Polymerase Chain Reaction ◽  
Oil Field ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Detection Range ◽  
Gene Copies ◽  
Application Potential ◽  
Sensitivity Specificity

Propane-oxidizing bacteria in surface soils are often used to indicate the position of oil and gas reservoirs. As a potential replacement for the laborious traditional culture-dependent counting method, we applied real-time fluorescent quantitative polymerase chain reaction detection as a quick and accurate technology for quantification of propane-oxidizing bacteria. The propane monooxygenase gene was set as the target and the assay is based on SYBR Green I dye. The detection range was from 9.75 × 108 to 9.75 × 101 gene copies/µl, with the lowest detected concentration of 9.75 copies/µl. All coefficient of variation values of the threshold cycle in the reproducibility test were better than 1%. The technique showed good sensitivity, specificity, and reproducibility. We also quantified the propane-oxidizing bacteria in soils from three vertical 250 cm profiles collected from an oil field, a gas field, and a nonoil gas field using the established technique. The results indicated that the presence of propane monooxygenase A genes in soils can indicate an oil or gas reservoir. Therefore, this technique can satisfy the requirements for microbial exploration of oil and gas.

scholarly journals Analysis of the Influence of Different Fracture Network Structures on the Production of Shale Gas Reservoirs

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ming Yue ◽  
Xiaohe Huang ◽  
Fanmin He ◽  
Lianzhi Yang ◽  
Weiyao Zhu ◽  
...  
Keyword(s):  
Finite Element ◽  
Shale Gas ◽  
Flow Direction ◽  
Fracture Network ◽  
Gas Production ◽  
Low Flow ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Gas Seepage

Volume fracturing is a key technology in developing unconventional gas reservoirs that contain nano/micron pores. Different fracture structures exert significantly different effects on shale gas production, and a fracture structure can be learned only in a later part of detection. On the basis of a multiscale gas seepage model considering diffusion, slippage, and desorption effects, a three-dimensional finite element algorithm is developed. Two finite element models for different fracture structures for a shale gas reservoir in the Sichuan Basin are established and studied under the condition of equal fracture volumes. One is a tree-like fracture, and the other is a lattice-like fracture. Their effects on the production of a fracture network structure are studied. Numerical results show that under the same condition of equal volumes, the production of the tree-like fracture is higher than that of the lattice-like fracture in the early development period because the angle between fracture branches and the flow direction plays an important role in the seepage of shale gas. In the middle and later periods, owing to a low flow rate, the production of the two structures is nearly similar. Finally, the lattice-like fracture model is regarded as an example to analyze the factors of shale properties that influence shale gas production. The analysis shows that gas production increases along with the diffusion coefficient and matrix permeability. The increase in permeability leads to a larger increase in production, but the decrease in permeability leads to a smaller decrease in production, indicating that the contribution of shale gas production is mainly fracture. The findings of this study can help better understand the influence of different shapes of fractures on the production in a shale gas reservoir.

Study on Production Performance Simulating the Low Permeability Dual Media Gas Reservoirs Pre and Post Fracturing

2011 ◽  
Vol 287-290 ◽  
pp. 86-91
Author(s):  
Li Ying Wang ◽  
Shu Sheng Gao ◽  
Wei Xiong ◽  
Hua Xun Liu
Keyword(s):  
Early Stage ◽  
Cross Flow ◽  
Flow Coefficient ◽  
Production Performance ◽  
Natural Fracture ◽  
Low Permeability ◽  
Gas Reservoirs ◽  
Penetration Ratio ◽  
Order Of Magnitude ◽  
Porosity And Permeability

Mathematical model of dual media reservoir fracturing wells was established and the corresponding numerical calculation program was developed based on the special relationship between porosity and permeability of dual media low permeability gas reservoirs. Through comparative analysis of numerical results of production performance pre and post fracturing, effects of cross flow coefficient and fracture penetration ratio were well studied. The results show that: after a period of production, pressure decline of the gas well decreases linearly with time, whether fracturing or not, showing pseudo-steady-state characteristics; in the early stage, pressure drop in the vertical well pre-fracturing is an order of magnitude larger than the post-fracturing well in the logarithmic coordinate; the less developed the natural fracture is, the smaller the cross flow coefficient is, and the more significant role the fracturing plays in yield increasing; when the fracture penetration ratio is between 0.25~0.50, it has less impact on production, so it is suggested that the fracture penetration ratio is controlled at about 0.25 in actual dual media dense gas reservoirs.

scholarly journals Comparative Study on the Reservoir Characteristics and Development Technologies of Two Typical Karst Weathering-Crust Carbonate Gas Reservoirs in China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Haijun Yan ◽  
Ailin Jia ◽  
Fankun Meng ◽  
Qinyu Xia ◽  
Wei Xu ◽  
...  
Keyword(s):  
Carbonate Reservoirs ◽  
Production Performance ◽  
Dynamic Monitoring ◽  
Weathering Crust ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Gas Field ◽  
Reservoir Characteristics ◽  
Reservoir Stimulation ◽  
Well Pattern

Carbonate reservoirs are the main reservoir types in China, which occupy the large ratio of reserves and production at present. The high-efficiency development of carbonate reservoirs is of great significance to assure the stability of national energy supply. The Lower Paleozoic reservoir in Jingbian gas field and the Sinian reservoir in Anyue gas field are two typical carbonate gas reservoirs, and their successful development experiences can provide significant references for other similar carbonate gas reservoirs. For Jingbian gas field, it is a lithological-stratigraphic reservoir developed in a westward monocline and multiple rows of nose-fold structures, and is a stable craton basin with simple palaeognomy distribution and stable connectivity, which has complex gas-water distribution. However, for Anyue gas field, it is a lithological-structural reservoir with multiple tectonic high points and multiple fault systems, and is biological dune beach facies under extensional setting with highly differentiated inside of the block in palaeognomy characteristics, which has limited connectivity and tectonic side water is in a local area. The difference of gas reservoir characteristics leads to the diverse development strategies. For these two gas reservoirs, although there are some similar aspects, such as the screen of enrichment areas, the application of irregular well pattern and reservoir stimulation techniques, the criteria of enrichment areas, the well types, and the means of reservoir stimulation are absolutely different. In addition, due to the differences of control reserves and production capacity for these two kinds of reservoirs, the mode of stable production is also different. The effective development of Jingbian gas field can give some references to the future exploitation on the Sinian gas reservoir. Firstly, the sedimentary characteristics should be studied comprehensively. Secondly, the distribution pattern and distribution characteristics of the palaeognomy should be found and determined. Thirdly, the distribution of fracture system in the reservoir should be depicted finely. Finally, dynamic monitoring on the production performance should be strengthened, and the management for this gas field should be improved further. The findings of this study can help for better understanding of the Karst weathering-crust carbonate gas reservoir formation characteristics and the optimal development technologies that should be taken in practice.

scholarly journals A Workflow for Integrated Geological Modeling for Shale Gas Reservoirs: A Case Study of the Fuling Shale Gas Reservoir in the Sichuan Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Xiaofei Shang ◽  
Huawei Zhao ◽  
Shengxiang Long ◽  
Taizhong Duan
Keyword(s):  
Shale Gas ◽  
Production Optimization ◽  
Natural Fracture ◽  
Geological Modeling ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Shale Gas Reservoirs ◽  
Stratigraphic Model

Shale gas reservoir evaluation and production optimization both require geological models. However, currently, shale gas modeling remains relatively conventional and does not reflect the unique characteristics of shale gas reservoirs. Based on a case study of the Fuling shale gas reservoir in China, an integrated geological modeling workflow for shale gas reservoirs is proposed to facilitate its popularization and application and well improved quality and comparability. This workflow involves four types of models: a structure-stratigraphic model, reservoir (matrix) parameter model, natural fracture (NF) model, and hydraulic fracture (HF) model. The modeling strategies used for the four types of models vary due to the uniqueness of shale gas reservoirs. A horizontal-well lithofacies sublayer calibration-based method is employed to build the structure-stratigraphic model. The key to building the reservoir parameter model lies in the joint characterization of shale gas “sweet spots.” The NF models are built at various scales using various methods. Based on the NF models, the HF models are built by extended simulation and microseismic inversion. In the entire workflow, various types of models are built in a certain sequence and mutually constrain one another. In addition, the workflow contains and effectively integrates multisource data. Moreover, the workflow involves multiple model integration processes, which is the key to model quality. The selection and optimization of modeling methods, the innovation and development of modeling algorithms, and the evaluation techniques for model uncertainty are areas where breakthroughs may be possible in the geological modeling of shale gas reservoirs. The workflow allows the complex process of geological modeling of shale gas reservoirs to be more systematic. It is of great significance for a dynamic analysis of reservoir development, from individual wells to the entire gas field, and for optimizing both development schemes and production systems.

scholarly journals Development and Calibration of a Semianalytic Model for Shale Wells with Nonuniform Distribution of Induced Fractures Based on ES-MDA Method

Energies ◽  
2020 ◽  
Vol 13 (14) ◽  
pp. 3718 ◽  
Author(s):  
Qi Zhang ◽  
Shu Jiang ◽  
Xinyue Wu ◽  
Yan Wang ◽  
Qingbang Meng
Keyword(s):  
Shale Gas ◽  
Fractal Dimensions ◽  
Nonuniform Distribution ◽  
Fracture System ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Unconventional Gas ◽  
Fracture Spacing ◽  
Unconventional Gas Reservoirs ◽  
Induced Fractures

Given reliable parameters, a newly developed semianalytic model could offer an efficient option to predict the performance of the multi-fractured horizontal wells (MFHWs) in unconventional gas reservoirs. However, two major challenges come from the accurate description and significant parameters uncertainty of stimulated reservoir volume (SRV). The objective of this work is to develop and calibrate a semianalytic model using the ensemble smoother with multiple data assimilation (ES-MDA) method for the uncertainty reduction in the description and forecasting of MFHWs with nonuniform distribution of induced fractures. The fractal dimensions of induced-fracture spacing (dfs) and aperture (dfa) and tortuosity index of induced-fracture system (θ) are included based on fractal theory to describe the properties of SRV region. Additionally, for shale gas reservoirs, gas transport mechanisms, e.g., viscous flow with slippage, Knudsen diffusion, and surface diffusion, among multi-media including porous kerogen, inorganic matter, and fracture system are taken into account and the model is verified. Then, the effects of the fractal dimensions and tortuosity index of induced fractures on MFHWs performances are analyzed. What follows is employing the ES-MDA method with the presented model to reduce uncertainty in the forecasting of gas production rate for MFHWs in unconventional gas reservoirs using a synthetic case for the tight gas reservoir and a real field case for the shale gas reservoir. The results show that when the fractal dimensions of induced-fracture spacing and aperture is smaller than 2.0 or the tortuosity index of induced-fracture system is larger than 0, the permeability of induced-fracture system decreases with the increase of the distance from hydraulic fractures (HFs) in SRV region. The large dfs or small θ causes the small average permeability of the induced-fracture system, which results in large dimensionless pseudo-pressure and small dimensionless production rate. The matching results indicate that the proposed method could enrich the application of the semianalytic model in the practical field.

Analysis on Petrophysical Properties of the Shale Gas Reservoir

2014 ◽  
Vol 977 ◽  
pp. 208-212
Author(s):  
Jian Fu ◽  
Xiao Min Tang ◽  
Yu Chen Liu
Keyword(s):  
Pore Structure ◽  
Mineral Composition ◽  
Shale Gas ◽  
Influential Factors ◽  
Petrophysical Properties ◽  
Gas Reservoirs ◽  
Gas Reservoir ◽  
Shale Gas Reservoir ◽  
Important Means ◽  
Storage Characteristics

As one of the most important means to obtain formation information, logging technology plays an important role in the identification and evaluation of shale gas reservoirs. This paper describs the formation mechanism and influential factors of shale gas reservoir storage characteristics from mineral composition and pore structure,etc. and discusses method for evaluating the TOC.

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