scholarly journals A Semianalytical Model for Analyzing the Infill Well-Caused Fracture Interference from Shale Gas Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sidong Fang ◽  
Yonghui Wu ◽  
Cheng Dai ◽  
Liqiang Ma ◽  
Hua Liu
Keyword(s):  
Shale Gas ◽  
Control Volume ◽  
Material Balance ◽  
Production Performance ◽  
Production Data ◽  
Model Parameters ◽  
Hydraulic Fractures ◽  
Late Time ◽  
Fracture Characterization ◽  
Proposed Model

Drilling infill well has been widely used in many plays to enhance the recovery of shale gas, but the infill well-caused fracture interference is a very important issue that should be taken into consideration. The well interference makes it difficult for the conventional models to make production predictions, fracture characterization, and production data analysis. In this paper, a semianalytical model is proposed for this purpose by discretizing the whole control volume of the parent and infill wells into several linear flow zones. In this way, three important issues can be further handled very naturally, including fracture connection between the parent and infill wells, different SRV properties for zones with different distances to the wellbore, and different production times for adjacent wellbores. The approximate expressions for different flow regimes are used in making production predictions in the time domain, and a flowing material balance method and a simple iteration are used to update the model parameters step by step. The proposed model is shown to be reasonable and accurate for handling multiwell interference problems after comparing with the commercial numerical simulator tNavigator. The synthetical cases show that the fracture parameters, SRV properties, and well infill time have a significant influence on the production performance of both the parent and infill wells. The results show that the production of the parent well will be dramatically enhanced when it is connected with the infill well via high-conductive hydraulic fractures. Longer unconnected fractures and more fracturing stages/clusters for the infill well will result in higher production for the infill well, but a negative effect is observed for the parent well. The permeability of the distant well SRV has a similar influence on the parent and infill wells. The results also show that late time well interference will result in a more significant increase in production rate on the log-log plots for the severe depletion around the parent well. Finally, the proposed model is used to analyze the production data of a field case from Fuling shale in Southwestern China. After analyzing the production data, several parameters can be obtained for both parent and infill wells, including the fracture lengths and conductivities, numbers of connected fractures, and the near and distant well permeabilities of the SRV. This gives a basic and practical technique for production prediction, formation and fracture evaluation, and well connectivity analysis from shale gas wells with fracture connection.

A Simple Method for Quantifying Inter-Well Communication Using Production Data from Single-Phase Shale Gas Reservoirs

2021 ◽  
Author(s):  
Hamidreza Hamdi ◽  
Hamid Behmanesh ◽  
Christopher R. Clarkson
Keyword(s):  
Numerical Simulation ◽  
Shale Gas ◽  
Analytical Method ◽  
Single Phase ◽  
Material Balance ◽  
Production Data ◽  
Hydraulic Fractures ◽  
Gas Reservoirs ◽  
Simple Method ◽  
Shale Gas Reservoirs

Abstract Hydraulic fracture/reservoir properties and fluid-in-place can be quantified by using rate-transient analysis (RTA) techniques applied to flow rates/pressures gathered from multi-fractured horizontal wells (MFHWs) completed in unconventional reservoirs. These methods are commonly developed for the analysis of production data from single wells without considering communication with nearby wells. However, in practice, wells drilled from the same pad can be in strong hydraulic communication with each other. This study aims to develop the theoretical basis for analyzing production data from communicating MFHWs completed in single-phase shale gas reservoirs. A simple and practical semi-analytical method is developed to quantify the communication between wells drilled from the same pad by analyzing online production data from the individual wells. This method is based on the communicating tanks model and employs the concepts of macroscopic material balance and the succession of pseudo-steady states. A set of nonlinear ordinary differential equations (ODEs) are generated and solved simultaneously using the efficient Adams-Bashforth-Moulton algorithm. The accuracy of the solutions is verified against robust numerical simulation. In the first example provided, a MFHW well-pair is presented where the wells are communicating through primary hydraulic fractures with different communication strengths. In the subsequent examples, the method is extended to consider production data from a three-well and a six-well pad with wine-rack-style completions. The developed model is flexible enough to account for asynchronous wells that are producing from distinct reservoir blocks with different fracture/rock properties. For all the studied cases, the semi-analytical method closely reproduces the results of fully numerical simulation. The results demonstrate that, in some cases, when new wells start to produce, the production rates of existing wells can drop significantly. The amount of productivity loss is a direct function of the communication strengths between the wells. The new method can accurately quantify the communication strength between wells through transmissibility multipliers between the hydraulic fractures that are adjusted to match individual well production data. In this study, a new simple and efficient semi-analytical method is presented that can be used to analyze online production data from multiple wells drilled from a pad simultaneously with minimal computation time. The main advantage of the developed method is its scalability, where additional wells can be added to the system very easily.

scholarly journals An Analytical Method for Parameter Interpretation of Fracture Networks in Shale Gas Reservoirs considering Uneven Support of Fractures

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Shijun Huang ◽  
Jiaojiao Zhang ◽  
Sidong Fang ◽  
Xifeng Wang
Keyword(s):  
Data Analysis ◽  
Shale Gas ◽  
Analytical Method ◽  
Material Balance ◽  
Gas Production ◽  
Production Data ◽  
Analysis Method ◽  
Gas Reservoirs ◽  
Data Analysis Method ◽  
Parameter Interpretation

In shale gas reservoirs, the production data analysis method is widely used to invert reservoir and fracture parameter, and productivity prediction. Compared with numerical models and semianalytical models, which have high computational cost, the analytical model is mostly used in the production data analysis method to characterize the complex fracture network formed after fracturing. However, most of the current calculation models ignore the uneven support of fractures, and most of them use a single supported fracture model to describe the flow characteristics, which magnifies the role of supported fracture to a certain extent. Therefore, in this study, firstly, the fractures are divided into supported fractures and unsupported fractures. According to the near-well supported fractures and far-well unsupported fractures, the SRV zone is divided into outer SRV and inner SRV. The four areas are characterized by different seepage models, and the analytical solutions of the models are obtained by Laplace transform and inverse transform. Secondly, the material balance pseudotime is introduced to process the production data under the conditions of variable production and variable pressure. The double logarithmic curves of normalized production rate, rate integration, the derivative of the integration, and material balance pseudotime are established, and the parameters are interpreted by fitting the theoretical curve to the measured data. Then, the accuracy of the method is verified by comparison the parameter interpretation results with well test results, and the influence of parameters such as the half-length and permeability of supported and unsupported fractures on gas production is analyzed. Finally, the proposed method is applied to four field cases in southwest China. This paper mainly establishes an analytical method for parameter interpretation after hydraulic fracturing based on the production data analysis method considering the uneven support of fractures, which is of great significance for understanding the mechanism of fracturing stimulation, optimization of fracturing parameters, and gas production forecast.

scholarly journals A dual-tube model for gas dynamics in fractured nanoporous shale formations

2014 ◽  
Vol 757 ◽  
pp. 943-971 ◽  
Author(s):  
I. Lunati ◽  
S. H. Lee
Keyword(s):  
Production Rate ◽  
Shale Gas ◽  
Structural Parameters ◽  
Knudsen Diffusion ◽  
Effective Diffusion ◽  
Reliable Estimate ◽  
Hydraulic Fractures ◽  
Late Time ◽  
Transport Mechanisms ◽  
Shale Formations

AbstractGas flow through fractured nanoporous shale formations is complicated by a hierarchy of structural features (ranging from nanopores to microseismic and hydraulic fractures) and by several transport mechanisms that differ from the standard viscous flow used in reservoir modelling. In small pores, self-diffusion becomes more important than advection; also, slippage effects and Knudsen diffusion might become relevant at low densities. We derive a nonlinear effective diffusion coefficient that describes the main transport mechanisms in shale-gas production. In dimensionless form, this coefficient depends only on a geometric factor (or dimensionless permeability) and on the kinetic model that describes the gas. To simplify the description of the complex structure of fractured shales, we observe that the production rate is controlled by the flow from the shale matrix (which has the smallest diffusivity) into the fracture network, which is assumed to produce instantaneously. Therefore, we propose to model the flow in the shale matrix and estimate the production rate with a simple bundle-of-dual-tubes model (BoDTM), in which each tube is characterized by two diameters (one for transport and the other for storage). The solution of a single tube is approximately self-similar at early time, but not at late time, when the gas flux decays exponentially owing to the finite length of the tube. To construct a BoDTM, a reliable estimate of the joint statistics of the matrix-porosity parameters is required. This can be either inferred from core measurements or postulated on the basis of somea prioriassumptions when information from laboratory and field measurements is scarce. By comparison with field production data from the Barnett shale-gas field, we demonstrate that BoDTM can be calibrated to estimate structural parameters of the shale formation and to predict the cumulative production of shale gas. Our framework has enough flexibility to construct models of increasing complexity that can be employed in the presence of a complex dataset or when more information is available.

scholarly journals Organoporosity Evaluation of Shale: A Case Study of the Lower Silurian Longmaxi Shale in Southeast Chongqing, China

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Fangwen Chen ◽  
Shuangfang Lu ◽  
Xue Ding
Keyword(s):  
Organic Carbon ◽  
Shale Gas ◽  
Material Balance ◽  
Model Parameters ◽  
Correction Coefficient ◽  
Hydrocarbon Generation ◽  
Gas Reservoir ◽  
Lower Silurian ◽  
Shale Gas Reservoir ◽  
Longmaxi Shale

The organopores play an important role in determining total volume of hydrocarbons in shale gas reservoir. The Lower Silurian Longmaxi Shale in southeast Chongqing was selected as a case to confirm the contribution of organopores (microscale and nanoscale pores within organic matters in shale) formed by hydrocarbon generation to total volume of hydrocarbons in shale gas reservoir. Using the material balance principle combined with chemical kinetics methods, an evaluation model of organoporosity for shale gas reservoirs was established. The results indicate that there are four important model parameters to consider when evaluating organoporosity in shale: the original organic carbon (w(TOC0)), the original hydrogen index (IH0), the transformation ratio of generated hydrocarbon (F(Ro)), and the organopore correction coefficient (C). The organoporosity of the Lower Silurian Longmaxi Shale in the Py1 well is from 0.20 to 2.76%, and the average value is 1.25%. The organoporosity variation trends and the residual organic carbon of Longmaxi Shale are consistent in section. The residual organic carbon is indicative of the relative levels of organoporosity, while the samples are in the same shale reservoirs with similar buried depths.

Density-Based Production-Data Analysis of Gas Wells With Significant Rock-Compressibility Effects

2015 ◽  
Vol 18 (02) ◽  
pp. 205-213 ◽  
Author(s):  
Miao Zhang ◽  
Luis F. Ayala
Keyword(s):  
High Pressure ◽  
Material Balance ◽  
Production Performance ◽  
Production Data ◽  
Correct Prediction ◽  
Well Performance ◽  
Gas Wells ◽  
Rock Compressibility ◽  
Large Formation ◽  
Compressibility Effects

Summary The state-of-the-art analysis of the production performance of gas wells relies on material-balance concepts combined with pseudopressure and pseudotime for rate-time decline analysis and reserves estimations. In many cases, rock compressibility and reservoir pore-volume (PV) change are either neglected or accounted for by replacing gas compressibility with total compressibility values. In this work, we extend the applicability of a rescaled exponential and density-based decline-analysis approach (Ayala and Ye 2013a, b; Zhang and Ayala 2014a, b) for the decline analysis of gas systems experiencing significant rock-compressibility effects. We formally derive the density-based analytical techniques that rigorously capture formation-compressibility effects during the analysis of gas-well-production data during boundary-dominated flow, which proves crucially important for high-pressure and/or large-formation-compressibility gas-reservoir systems. The proposed formulation enables the calculation and correct prediction of well performance and original gas in place (OGIP) by incorporating formation compressibility and the change of reservoir PV effects, which may prove crucially important in high-pressure and/or relatively large-formation-compressibility gas reservoirs. We also present the associated straight-line analysis technique used for OGIP determination on the basis of the density approach applicable to constant-bottomhole-pressure production and variable-flow-rate/pressure-drop systems.

An Integrative Model To Simulate Gas Transport and Production Coupled With Gas Adsorption, Non-Darcy Flow, Surface Diffusion, and Stress Dependence in Organic-Shale Reservoirs

SPE Journal ◽  
2016 ◽  
Vol 22 (01) ◽  
pp. 244-264 ◽  
Author(s):  
Jing Wang ◽  
Haishan Luo ◽  
Huiqing Liu ◽  
Fei Cao ◽  
Zhitao Li ◽  
...  
Keyword(s):  
Surface Diffusion ◽  
Shale Gas ◽  
Gas Adsorption ◽  
Gas Transport ◽  
Adsorbed Layer ◽  
Darcy Flow ◽  
Integrative Model ◽  
Model Parameters ◽  
Hydraulic Fractures ◽  
Stress Dependence

Summary Gas adsorption, stress dependence, non-Darcy flow, and surface diffusion of the adsorbed layer are significant mechanisms in shale-gas reservoirs. However, the volume occupied by the adsorbed layer is generally overlooked by current industry standards and numerical models. In addition, stress dependence of matrix pores does not draw as much attention as hydraulic fractures, and surface diffusion has not been included in commercial simulators. Moreover, all these effects significantly affect each other, which can lead to additional complexity of gas transport and production. Therefore, development of an integrative model with consideration of these complicated mechanisms is needed. In this paper, we develop such a fully coupled model for shale-gas-reservoir simulations. We present the derivation of models reflecting the time-dependence effects of gas adsorption/desorption upon original gas in place (OGIP) and petrophysical properties. In particular, both the Langmuir and Brunauer, Emmett, and Teller (BET) (Brunauer et al. 1938) isotherms are included by use of a unified formula. Surface diffusion of adsorbed layer is also added to this model on the basis of rigorous derivation. More features, such as non-Darcy flow and stress dependence in matrix, natural fractures, hydraulic fractures, and leakage effect between matrix and natural fractures, are incorporated. After that, we present an implicit numerical algorithm to solve the model. Numerical simulations were performed in both 1D and 3D cases and compared with two sets of experimental data and three sets of production data in Marcellus and Barnett shale-gas fields. The simulations indicated that the new simulator cannot only lead to consistent results with these data, but also gives an accurate estimation of OGIP, which traditional models failed to do. It is noted that the model parameters we used for the simulations were close to the values suggested by the literature, if available. By use of this validated simulator, we demonstrated applications with respect to real shale reservoirs, studied the effects of the model parameters upon the gas transport and production, and achieved a variety of new insights.

An Integrated Model for History Matching and Predicting Reservoir Performance of Gas/Condensate Wells

2013 ◽  
Vol 16 (04) ◽  
pp. 412-422
Author(s):  
A.M.. M. Farid ◽  
Ahmed H. El-Banbi ◽  
A.A.. A. Abdelwaly
Keyword(s):  
History Matching ◽  
Material Balance ◽  
Integrated Model ◽  
Gas Condensate ◽  
Production Performance ◽  
Productivity Index ◽  
Production Data ◽  
Fluid Composition ◽  
Two Phase ◽  
Reservoir Simulator

Summary The depletion performance of gas/condensate reservoirs is highly influenced by changes in fluid composition below the dewpoint. The long-term prediction of condensate/gas reservoir behavior is therefore difficult because of the complexity of both composition variation and two-phase-flow effects. In this paper, an integrated model was developed to simulate gas-condensate reservoir/well behavior. The model couples the compositional material balance or the generalized material-balance equations for reservoir behavior, the two-phase pseudo integral pressure for near-wellbore behavior, and outflow correlations for wellbore behavior. An optimization algorithm was also used with the integrated model so it can be used in history-matching mode to estimate original gas in place (OGIP), original oil in place (OOIP), and productivity-index (PI) parameters for gas/condensate wells. The model also can be used to predict the production performance for variable tubinghead pressure (THP) and variable production rate. The model runs fast and requires minimal input. The developed model was validated by use of different simulation cases generated with a commercial compositional reservoir simulator for a variety of reservoir and well conditions. The results show a good agreement between the simulation cases and the integrated model. After validating the integrated model against the simulated cases, the model was used to analyze production data for a rich-gas/condensate field (initial condensate/gas ratio of 180 bbl/ MMscf). THP data for four wells were used along with basic reservoir and production data to obtain original fluids in place and PIs of the wells. The estimated parameters were then used to forecast the gas and condensate production above and below the dewpoint. The model is also capable of predicting reservoir pressure, bottomhole flowing pressure, and THP and can account for completion changes when they occur.

Efficient Coupled Multiphase-Flow and Geomechanics Modeling of Well Performance and Stress Evolution in Shale-Gas Reservoirs Considering Dynamic Fracture Properties

SPE Journal ◽  
2020 ◽  
Vol 25 (03) ◽  
pp. 1523-1542 ◽  
Author(s):  
Lijun Liu ◽  
Yongzan Liu ◽  
Jun Yao ◽  
Zhaoqin Huang
Keyword(s):  
Multiphase Flow ◽  
Dynamic Fracture ◽  
Shale Gas ◽  
Hydraulic Fractures ◽  
Stress Evolution ◽  
Well Performance ◽  
Gas Reservoirs ◽  
Fracture Properties ◽  
Shale Gas Reservoirs ◽  
Proposed Model

Summary Significant conductivity losses of both propped hydraulic fractures and unpropped natural fractures are widely observed by laboratory experiments and field studies in shale-gas reservoirs. Previous studies have not well-considered the effects of dynamic fracture properties, which limit the accurate prediction of well performance and stress evolution. In this study, an efficient coupled flow and geomechanics model is proposed to characterize the dynamic fracture properties and examine their effects on well performance and stress evolution in complex fractured shale-gas reservoirs. In our proposed model, a unified compositional model with nonlinear transport mechanisms is used to accurately describe multiphase flow in shale formations. The embedded discrete fracture model (EDFM) is used to explicitly model the complex fracture networks. Different fracture constitutive models are implemented to describe the dynamic properties of hydraulic fractures and natural fractures, respectively. The finite-volume method (FVM) and finite-element method (FEM) are used for the space discretization of flow and geomechanics equations, respectively, and the coupled problem is solved by the fixed-stress split iterative method. The coupled model is validated against classical analytical solutions. After that, the proposed model is used to investigate the effects of hydraulic-fracture and natural-fracture properties on production behavior as well as pressure and stress evolution of shale-gas reservoirs. With the dynamic fracture properties incorporated, our model can predict the well production more accurately, and provide more realistic stress evolution that is essential for the design and optimization of refracturing and infill-well drilling.

Key Factors in Shale Gas Modeling and Simulation

2014 ◽  
Vol 59 (4) ◽  
pp. 987-1004 ◽  
Author(s):  
Łukasz Klimkowski ◽  
Stanisław Nagy
Keyword(s):  
Shale Gas ◽  
Gas Production ◽  
Production Performance ◽  
Hydraulic Fractures ◽  
Well Performance ◽  
Key Factors ◽  
Gas Well ◽  
Well Production ◽  
Multi Stage ◽  
The Impact

Abstract Multi-stage hydraulic fracturing is the method for unlocking shale gas resources and maximizing horizontal well performance. Modeling the effects of stimulation and fluid flow in a medium with extremely low permeability is significantly different from modeling conventional deposits. Due to the complexity of the subject, a significant number of parameters can affect the production performance. For a better understanding of the specifics of unconventional resources it is necessary to determine the effect of various parameters on the gas production process and identification of parameters of major importance. As a result, it may help in designing more effective way to provide gas resources from shale rocks. Within the framework of this study a sensitivity analysis of the numerical model of shale gas reservoir, built based on the latest solutions used in industrial reservoir simulators, was performed. The impact of different reservoir and hydraulic fractures parameters on a horizontal shale gas well production performance was assessed and key factors were determined.

Sign in / Sign up

Export Citation Format

Share Document