scholarly journals Numerical Investigation of Multistage Fractured Horizontal Wells considering Multiphase Flow and Geomechanical Effects

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Jun Li ◽  
Yuetian Liu ◽  
Kecong Ma
Keyword(s):  
Rock Mechanics ◽  
Shale Gas ◽  
Early Stage ◽  
Gas Production ◽  
Phase Flow ◽  
Gas Reservoirs ◽  
Two Phase ◽  
Flow Process ◽  
Stimulated Reservoir Volume ◽  
Shale Gas Reservoirs

Hydraulic fracturing is a key technology in unconventional reservoir production, yet many simulators only consider the single-phase flow of shale gas, ignoring the two-phase flow process caused by the retained fracturing fluid in the early stage of production. In this study, a three-dimensional fluid–gas–solid coupling reservoir model is proposed, and the governing equations which involve the early injection water phenomenon and stress-sensitive characteristics of shale gas reservoirs are established. The finite element–finite difference method was used for discretisation of stress and strain equations and the equations of flow balances. Further, a sensitivity analysis was conducted to analyse fracture deformation changes in the production. Fracture characteristics under different rock mechanics coefficients were simulated, and the influence of rock mechanics parameters on productivity was further characterised. The stimulated reservoir volume zone permeability could determine the retrofitting effect, the permeability increased from 0.02 to 0.1 mD, and cumulative gas production increased from 18.08 to 26.42 million m3, thus showing an increase of 8.34 million m3, or 46%. The effect of Young’s modulus on the yield was smaller than Poisson’s ratio and the width and length of the fractures. Production was most sensitive to the length of the fractures. The length of the fracture increased from 200 to 400 m, and the cumulative gas production increased from 26.44 to 38.34 million m3, showing an increase of 11.9 million m3, or 45%. This study deepens the understanding of the production process of shale gas reservoirs and has significance for the fluid–gas–solid coupling of shale gas reservoirs.

scholarly journals Water-Gas Two-Phase Flow Behavior of Multi-Fractured Horizontal Wells in Shale Gas Reservoirs

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 664 ◽  
Author(s):  
Lei Li ◽  
Guanglong Sheng ◽  
Yuliang Su
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Flow Behavior ◽  
Horizontal Wells ◽  
Gas Production ◽  
Phase Flow ◽  
Gas Reservoirs ◽  
Two Phase ◽  
Fractured Horizontal Wells ◽  
Water Gas

Hydraulic fracturing is a necessary method to develop shale gas reservoirs effectively and economically. However, the flow behavior in multi-porosity fractured reservoirs is difficult to characterize by conventional methods. In this paper, combined with apparent porosity/permeability model of organic matter, inorganic matter and induced fractures, considering the water film in unstimulated reservoir volume (USRV) region water and bulk water in effectively stimulated reservoir volume (ESRV) region, a multi-media water-gas two-phase flow model was established. The finite difference is used to solve the model and the water-gas two-phase flow behavior of multi-fractured horizontal wells is obtained. Mass transfer between different-scale media, the effects of pore pressure on reservoirs and fluid properties at different production stages were considered in this model. The influence of the dynamic reservoir physical parameters on flow behavior and gas production in multi-fractured horizontal wells is studied. The results show that the properties of the total organic content (TOC) and the inherent porosity of the organic matter affect gas production after 40 days. With the gradual increase of production time, the gas production rate decreases rapidly compared with the water production rate, and the gas saturation in the inorganic matter of the ESRV region gradually decreases. The ignorance of stress sensitivity would cause the gas production increase, and the ignorance of organic matter shrinkage decrease the gas production gradually. The water film mainly affects gas production after 100 days, while the bulk water has a greater impact on gas production throughout the whole period. The research provides a new method to accurately describe the two-phase fluid flow behavior in different scale media of fractured shale gas reservoirs.

scholarly journals Production Decline Analysis for Two-Phase Flow in Multifractured Horizontal Well in Shale Gas Reservoirs

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Wei-Yang Xie ◽  
Xiao-Ping Li ◽  
Lie-Hui Zhang ◽  
Xiao-Hua Tan ◽  
Jun-Chao Wang ◽  
...  
Keyword(s):  
Shale Gas ◽  
Horizontal Well ◽  
Flow Model ◽  
Transient Flow ◽  
Two Phase Flow ◽  
Hydraulic Fractures ◽  
Phase Flow ◽  
Gas Reservoirs ◽  
Two Phase ◽  
Shale Gas Reservoirs

After multistage fracturing, the flowback of fracturing fluid will cause two-phase flow through hydraulic fractures in shale gas reservoirs. With the consideration of two-phase flow and desorbed gas transient diffusion in shale gas reservoirs, a two-phase transient flow model of multistage fractured horizontal well in shale gas reservoirs was created. Accurate solution to this flow model is obtained by the use of source function theory, Laplace transform, three-dimensional eigenvalue method, and orthogonal transformation. According to the model’s solution, the bilogarithmic type curves of the two-phase model are illustrated, and the production decline performance under the effects of hydraulic fractures and shale gas reservoir properties are discussed. The result obtained in this paper has important significance to understand pressure response characteristics and production decline law of two-phase flow in shale gas reservoirs. Moreover, it provides the theoretical basis for exploiting this reservoir efficiently.

scholarly journals Investigation of the Main Factors During Shale-gas Production Using Grey Relational Analysis

2016 ◽  
Vol 9 (1) ◽  
pp. 207-215 ◽  
Author(s):  
Hongling Zhang ◽  
Jing Wang ◽  
Haiyong Zhang
Keyword(s):  
Shale Gas ◽  
Gas Production ◽  
Gas Reservoirs ◽  
Fracture Conductivity ◽  
Matrix Permeability ◽  
Shale Gas Reservoirs ◽  
Main Factors ◽  
Grey Relational ◽  
The Impact ◽  
Half Length

Shale gas is one of the primary types of unconventional reservoirs to be exploited in search for long-lasting resources. Production from shale gas reservoirs requires horizontal drilling with hydraulic fracturing to achieve the most economic production. However, plenty of parameters (e.g., fracture conductivity, fracture spacing, half-length, matrix permeability, and porosity,etc) have high uncertainty that may cause unexpected high cost. Therefore, to develop an efficient and practical method for quantifying uncertainty and optimizing shale-gas production is highly desirable. This paper focuses on analyzing the main factors during gas production, including petro-physical parameters, hydraulic fracture parameters, and work conditions on shale-gas production performances. Firstly, numerous key parameters of shale-gas production from the fourteen best-known shale gas reservoirs in the United States are selected through the correlation analysis. Secondly, a grey relational grade method is used to quantitatively estimate the potential of developing target shale gas reservoirs as well as the impact ranking of these factors. Analyses on production data of many shale-gas reservoirs indicate that the recovery efficiencies are highly correlated with the major parameters predicted by the new method. Among all main factors, the impact ranking of major factors, from more important to less important, is matrix permeability, fracture conductivity, fracture density of hydraulic fracturing, reservoir pressure, total organic content (TOC), fracture half-length, adsorbed gas, reservoir thickness, reservoir depth, and clay content. This work can provide significant insights into quantifying the evaluation of the development potential of shale gas reservoirs, the influence degree of main factors, and optimization of shale gas production.

Study Evaluates Fracturing Interference for Multiwell Pads in Shale Gas Reservoirs

2021 ◽  
Vol 73 (08) ◽  
pp. 67-68
Author(s):  
Chris Carpenter
Keyword(s):  
Hydraulic Fracturing ◽  
Shale Gas ◽  
Technical Conference ◽  
Gas Production ◽  
Gas Reservoirs ◽  
Well Drilling ◽  
Recovery Potential ◽  
Shale Gas Reservoirs ◽  
Well Spacing ◽  
Southwest Region

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 201694, “Interwell Fracturing Interference Evaluation of Multiwell Pads in Shale Gas Reservoirs: A Case Study in WY Basin,” by Youwei He, SPE, Jianchun Guo, SPE, and Yong Tang, Southwest Petroleum University, et al., prepared for the 2020 SPE Annual Technical Conference and Exhibition, originally scheduled to be held in Denver, Colorado, 5–7 October. The paper has not been peer reviewed. The paper aims to determine the mechanisms of fracturing interference for multiwell pads in shale gas reservoirs and evaluate the effect of interwell fracturing interference on production. Field data of 56 shale gas wells in the WY Basin are applied to calculate the ratio of affected wells to newly fractured wells and understand its influence on gas production. The main controlling factors of fracturing interference are determined, and the interwell fracturing interacting types are presented. Production recovery potential for affected wells is analyzed, and suggestions for mitigating fracturing interference are proposed. Interwell Fracturing Interference Evaluation The WY shale play is in the southwest region of the Sichuan Basin, where shale gas reserves in the Wufeng-Longmaxi formation are estimated to be the highest in China. The reservoir has produced hydrocarbons since 2016. Infill well drilling and massive hydraulic fracturing operations have been applied in the basin. Each well pad usually is composed of six to eight multifractured horizontal wells (MFHWs). Well spacing within one pad, or the distance between adjacent well pads, is so small that fracture interference can occur easily between infill wells and parent wells. Fig. 1 shows the number of wells affected by in-fill well fracturing from 2016 to 2019 in the basin. As the number of newly drilled wells increased between 2017 and 2019, the number of wells affected by hydraulic fracturing has greatly increased. The number of wells experiencing fracturing interaction has reached 65 in the last 4 years at the time of writing.

Rock mechanics of shear rupture in shale gas reservoirs

2016 ◽  
Vol 36 ◽  
pp. 943-949 ◽  
Author(s):  
Jinghong Hu ◽  
Shigang Yang ◽  
Daoming Fu ◽  
Ray Rui ◽  
Yanlong Yu ◽  
...  
Keyword(s):  
Rock Mechanics ◽  
Shale Gas ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Shear Rupture

scholarly journals Iterative Analytical Solutions for Nonlinear Two-Phase Flow with Gas Solubility in Shale Gas Reservoirs

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Xiaoji Shang ◽  
J. G. Wang ◽  
Zhizhen Zhang
Keyword(s):  
Capillary Pressure ◽  
Analytical Solutions ◽  
Shale Gas ◽  
Nonlinear Term ◽  
Two Phase Flow ◽  
Gas Production ◽  
Phase Flow ◽  
Gas Solubility ◽  
Production Rates ◽  
Two Phase

The governing equations of a two-phase flow have a strong nonlinear term due to the interactions between gas and water such as capillary pressure, water saturation, and gas solubility. This nonlinearity is usually ignored or approximated in order to obtain analytical solutions. The impact of such ignorance on the accuracy of solutions has not been clear so far. This study seeks analytical solutions without ignoring this nonlinear term. Firstly, a nonlinear mathematical model is developed for the two-phase flow of gas and water during shale gas production. This model also considers the effects of gas solubility in water. Then, iterative analytical solutions for pore pressures and production rates of gas and water are derived by the combination of travelling wave and variational iteration methods. Thirdly, the convergence and accuracy of the solutions are checked through history matching of two sets of gas production data: a China shale gas reservoir and a horizontal Barnett shale well. Finally, the effects of the nonlinear term, shale gas solubility, and entry capillary pressure on the shale gas production rate are investigated. It is found that these iterative analytical solutions can be convergent within 2-3 iterations. The solutions can well describe the production rates of both gas and water. The nonlinear term can significantly affect the forecast of shale gas production in both the short term and the long term. Entry capillary pressure and shale gas solubility in water can also affect shale gas production rates of shale gas and water. These analytical solutions can be used for the fast calculation of the production rates of both shale gas and water in the two-phase flow stage.

scholarly journals The Evaluation and Sensitivity of Decline Curve Modelling

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2765
Author(s):  
Prinisha Manda ◽  
Diakanua Nkazi
Keyword(s):  
Shale Gas ◽  
Goodness Of Fit ◽  
Accuracy Assessment ◽  
Gas Production ◽  
Production Performance ◽  
Logistic Growth ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Decline Curve ◽  
Exponential Decline

The development of prediction tools for production performance and the lifespan of shale gas reservoirs has been a focus for petroleum engineers. Several decline curve models have been developed and compared with data from shale gas production. To accurately forecast the estimated ultimate recovery for shale gas reservoirs, consistent and accurate decline curve modelling is required. In this paper, the current decline curve models are evaluated using the goodness of fit as a measure of accuracy with field data. The evaluation found that there are advantages in using the current DCA models; however, they also have limitations associated with them that have to be addressed. Based on the accuracy assessment conducted on the different models, it appears that the Stretched Exponential Decline Model (SEDM) and Logistic Growth Model (LGM), followed by the Extended Exponential Decline Model (EEDM), the Power Law Exponential Model (PLE), the Doung’s Model, and lastly, the Arps Hyperbolic Decline Model, provide the best fit with production data.

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