scholarly journals Transient-Flow Modeling of Vertical Fractured Wells with Multiple Hydraulic Fractures in Stress-Sensitive Gas Reservoirs

2019 ◽  
Vol 9 (7) ◽  
pp. 1359 ◽  
Author(s):  
Ping Guo ◽  
Zhen Sun ◽  
Chao Peng ◽  
Hongfei Chen ◽  
Junjie Ren
Keyword(s):  
Hydraulic Fracture ◽  
Transient Flow ◽  
Superposition Principle ◽  
Pressure Profile ◽  
Stress Sensitivity ◽  
Hydraulic Fractures ◽  
Transient Pressure ◽  
Gas Reservoirs ◽  
Type Curves ◽  
Vertical Well

Massive hydraulic fracturing of vertical wells has been extensively employed in the development of low-permeability gas reservoirs. The existence of multiple hydraulic fractures along a vertical well makes the pressure profile around the vertical well complex. This paper studies the pressure dependence of permeability to develop a seepage model of vertical fractured wells with multiple hydraulic fractures. Both transformed pseudo-pressure and perturbation techniques have been employed to linearize the proposed model. The superposition principle and a hybrid analytical-numerical method were used to obtain the bottom-hole pseudo-pressure solution. Type curves for pseudo-pressure are presented and identified. The effects of the relevant parameters (such as dimensionless permeability modulus, fracture conductivity coefficient, hydraulic-fracture length, angle between the two adjacent hydraulic fractures, the difference of the hydraulic-fracture lengths, and hydraulic-fracture number) on the type curve and the error caused by neglecting the stress sensitivity are discussed in detail. The proposed work can enrich the understanding of the influence of the stress sensitivity on the performance of a vertical fractured well with multiple hydraulic fractures and can be used to more accurately interpret and forecast the transient pressure.

The effect of hydraulic-fracture parameters on the welltest response of multi-fractured tight-gas reservoirs

2013 ◽  
Vol 53 (1) ◽  
pp. 375
Author(s):  
Chaolang Qiu ◽  
Mofazzal Hossain ◽  
Hassan Bahrami ◽  
Yangfan Lu
Keyword(s):  
Hydraulic Fracture ◽  
Transient Flow ◽  
Hydraulic Fractures ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Pressure Derivative ◽  
Unconventional Gas ◽  
Tight Gas Reservoirs ◽  
Fracture Parameters ◽  
Unconventional Gas Reservoirs

With the reduction of conventional reserves, the demand and exploration of unconventional sources becomes increasingly important in the energy supply system. Low permeability, low porosity, and the complexities of rock formation in unconventional gas reservoirs make it difficult to extract commercially viable gas resources. Hydraulic fracture is the most common technique used for commercial production of hydrocarbon resources from unconventional tight-gas reservoirs. Due to the existence of an extremely long transient-flow period in tight-gas reservoirs, the interpretation of welltest data based on conventional welltest analysis is quite challenging, and could potentially lead to misleading results. This peer-reviewed paper presents a new approach based on a log-log reciprocal rate derivative plot. Emphases are given on the identification of factors affecting the welltest response in multiple hydraulic-fractured wells in unconventional gas reservoirs based on numerical simulation. The objective is to investigate the sensitivity of various reservoir and hydraulic-fracture parameters, such as multiple hydraulic-fracture size, fracture number and fracture orientation on welltest response, and the effect of the pressure derivative curve on the slopes of welltest diagnostic plots, as well as on well productivity performance. The results can be used to understand the welltest response for different hydraulic-fracturing scenarios for the efficiency and characteristics of hydraulic fractures.

scholarly journals Incremental and acceleration production estimation and their effect on optimization of well infill locations in tight gas reservoirs

2021 ◽  
Author(s):  
Atheer Dheyauldeen ◽  
Omar Al-Fatlawi ◽  
Md Mofazzal Hossain
Keyword(s):  
Transient Flow ◽  
Development Planning ◽  
Main Role ◽  
Gas Reservoirs ◽  
Type Curves ◽  
Field Development ◽  
Drilling Performance ◽  
Well Location ◽  
Infill Drilling ◽  
Tight Formations

AbstractThe main role of infill drilling is either adding incremental reserves to the already existing one by intersecting newly undrained (virgin) regions or accelerating the production from currently depleted areas. Accelerating reserves from increasing drainage in tight formations can be beneficial considering the time value of money and the cost of additional wells. However, the maximum benefit can be realized when infill wells produce mostly incremental recoveries (recoveries from virgin formations). Therefore, the prediction of incremental and accelerated recovery is crucial in field development planning as it helps in the optimization of infill wells with the assurance of long-term economic sustainability of the project. Several approaches are presented in literatures to determine incremental and acceleration recovery and areas for infill drilling. However, the majority of these methods require huge and expensive data; and very time-consuming simulation studies. In this study, two qualitative techniques are proposed for the estimation of incremental and accelerated recovery based upon readily available production data. In the first technique, acceleration and incremental recovery, and thus infill drilling, are predicted from the trend of the cumulative production (Gp) versus square root time function. This approach is more applicable for tight formations considering the long period of transient linear flow. The second technique is based on multi-well Blasingame type curves analysis. This technique appears to best be applied when the production of parent wells reaches the boundary dominated flow (BDF) region before the production start of the successive infill wells. These techniques are important in field development planning as the flow regimes in tight formations change gradually from transient flow (early times) to BDF (late times) as the production continues. Despite different approaches/methods, the field case studies demonstrate that the accurate framework for strategic well planning including prediction of optimum well location is very critical, especially for the realization of the commercial benefit (i.e., increasing and accelerating of reserve or assets) from infilled drilling campaign. Also, the proposed framework and findings of this study provide new insight into infilled drilling campaigns including the importance of better evaluation of infill drilling performance in tight formations, which eventually assist on informed decisions process regarding future development plans.

Welltest analysis of hydraulically fractured tight gas reservoirs: a field example from Perth Basin, Western Australia

2012 ◽  
Vol 52 (1) ◽  
pp. 587 ◽  
Author(s):  
Hassan Bahrami ◽  
Vineeth Jayan ◽  
Reza Rezaee ◽  
Dr Mofazzal Hossain
Keyword(s):  
Radial Flow ◽  
Second Derivative ◽  
Tight Gas ◽  
Transient Pressure ◽  
Gas Reservoirs ◽  
Type Curves ◽  
Tight Gas Reservoirs ◽  
Diagnostic Plots ◽  
Reservoir Permeability ◽  
Reservoir Flow

Welltest interpretation requires the diagnosis of reservoir flow regimes to determine basic reservoir characteristics. In hydraulically fractured tight gas reservoirs, the reservoir flow regimes may not clearly be revealed on diagnostic plots of transient pressure and its derivative due to extensive wellbore storage effect, fracture characteristics, heterogeneity, and complexity of reservoir. Thus, the use of conventional welltest analysis in interpreting the limited acquired data may fail to provide reliable results, causing erroneous outcomes. To overcome such issues, the second derivative of transient pressure may help eliminate a number of uncertainties associated with welltest analysis and provide a better estimate of the reservoir dynamic parameters. This paper describes a new approach regarding welltest interpretation for hydraulically fractured tight gas reservoirs—using the second derivative of transient pressure. Reservoir simulations are run for several cases of non-fractured and hydraulically fractured wells to generate different type curves of pressure second derivative, and for use in welltest analysis. A field example from a Western Australian hydraulically fractured tight gas welltest analysis is shown, in which the radial flow regime could not be identified using standard pressure build-up diagnostic plots; therefore, it was not possible to have a reliable estimate of reservoir permeability. The proposed second derivative of pressure approach was used to predict the radial flow regime trend based on the generated type curves by reservoir simulation, to estimate the reservoir permeability and skin factor. Using this analysis approach, the permeability derived from the welltest was in good agreement with the average core permeability in the well, thus confirming the methodology’s reliability.

Production Performance Analysis for Multi-Branched Horizontal Wells in Composite Coal Bed Methane Reservoir Considering Stress Sensitivity

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Ruizhong Jiang ◽  
Xiuwei Liu ◽  
Yongzheng Cui ◽  
Xing Wang ◽  
Yue Gao ◽  
...  
Keyword(s):  
Superposition Principle ◽  
Horizontal Wells ◽  
Stress Sensitivity ◽  
Field Application ◽  
Model Verification ◽  
Production Performance ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Element Discretization ◽  
Type Curves

Abstract Coal bed methane (CBM) significantly contributes to unconventional energy resources. With the development of the drilling technology, multi-branched horizontal wells (MBHWs) have been put into the exploitation of CBM. In this paper, a semi-analytical mathematical model is introduced to study the production characteristics of MBHWs in the composite CBM reservoir. Stress sensitivity, composite reservoir, and complex seepage mechanisms (desorption, diffusion, and Darcy flow) are taken into consideration. Through Pedrosa transformation, Perturbation transformation, Laplace transformation, Finite cosine transformation, element discretization, superposition principle, and Stehfest numerical inversion, pseudo-pressure dynamic curves and production decline curves are plotted and 13 flow regimes are divided. Then, the sensitivity analysis of related parameters is conducted to study the influences of these parameters based on these two type curves. Model verification and field application are introduced which shows that the model is reliable. The model proposed in this paper and relevant results analysis can provide some significant guidance for a better understanding of the production behavior of MBHWs in the composite CBM reservoir.

scholarly journals Transient Pressure and Rate Decline Analysis for Horizontal Well in Stress-Sensitive Composite Reservoir

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Yu Huang ◽  
Xiaoping Li ◽  
Xiaohua Tan
Keyword(s):  
Horizontal Well ◽  
Transient Flow ◽  
Orthogonal Transformation ◽  
Flow Analysis ◽  
Analytic Solutions ◽  
Stress Sensitivity ◽  
Transient Pressure ◽  
Regular Perturbation ◽  
Transient Flow Analysis ◽  
Permeability Modulus

The existence of stress sensitivity effect made the percolation mechanism of low-permeability reservoirs significantly complex. Further, numerous reservoirs have composite stratum properties in actual development procedure. This paper based on the concept of permeability stress sensitivity presents an unsteady flow model for horizontal well taking both stress sensitivity and composite reservoir into account. Analytic solutions for the transient pressure and the rate decline behaviors are obtained by comprehensive utilization of regular perturbation method, Laplace transformation, orthogonal transformation, and Stehfest numerical inversion. The example analysis verifies that the proposed model is reliable and practical. Likewise, there is a discussion of the influence of permeability modulus and other relevant parameters on the transient pressure and the rate decline for horizontal well in stress-sensitive composite reservoir. The work of this paper improved the previous researches and provided a more accurate basis for transient flow analysis and formation evaluation of this typical reservoir.

Optimal Designs of Well Pattern for the Development of Tight Gas Reservoirs (TGRs)

2016 ◽  
Vol 9 (1) ◽  
pp. 77-90
Author(s):  
Jiao Yuwei ◽  
Xia Jing ◽  
Yan Jianye ◽  
Xu Daicai
Keyword(s):  
Horizontal Well ◽  
Optimal Designs ◽  
Hydraulic Fractures ◽  
Stress Effect ◽  
Tight Gas ◽  
Gas Reservoirs ◽  
Vertical Well ◽  
Fractured Horizontal Well ◽  
Well Pattern ◽  
Reservoir Conditions

Both horizontal well and fractured-horizontal well have been widely used to develop TGRs. However, the costs of horizontal well and fractured-horizontal well are much higher than the vertical well. Therefore, it is necessary to consider the reservoir conditions for evaluating the potential benefit when choosing well pattern or designing well parameters. In this paper, a simulator of simulating the development of TGRs including slippage flow and stress dependence in matrix, and high-velocity non-Darcy flow and stress effect in hydraulic fractures was firstly developed. Then, it was used to study the development effects of different TGRs using different well patterns and well parameters. Based on the simulation results, the incremental ratio models of horizontal well to vertical well and fractured-horizontal well to horizontal well were achieved. These models can be used to predict the incremental production using horizontal well or fractured-horizontal well. We also obtained the plates of choosing well pattern and designing the corresponding parameters to achieve a good profit in the field.

scholarly journals History Matching and Forecast of Shale Gas Production Considering Hydraulic Fracture Closure

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1634 ◽  
Author(s):  
Juhyun Kim ◽  
Youngjin Seo ◽  
Jihoon Wang ◽  
Youngsoo Lee
Keyword(s):  
Shale Gas ◽  
Hydraulic Fracture ◽  
History Matching ◽  
Gas Flow ◽  
Fluid Pressure ◽  
Gas Production ◽  
Hydraulic Fractures ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Fracture Closure

Most shale gas reservoirs have extremely low permeability. Predicting their fluid transport characteristics is extremely difficult due to complex flow mechanisms between hydraulic fractures and the adjacent rock matrix. Recently, studies adopting the dynamic modeling approach have been proposed to investigate the shape of the flow regime between induced and natural fractures. In this study, a production history matching was performed on a shale gas reservoir in Canada’s Horn River basin. Hypocenters and densities of the microseismic signals were used to identify the hydraulic fracture distributions and the stimulated reservoir volume. In addition, the fracture width decreased because of fluid pressure reduction during production, which was integrated with the dynamic permeability change of the hydraulic fractures. We also incorporated the geometric change of hydraulic fractures to the 3D reservoir simulation model and established a new shale gas modeling procedure. Results demonstrate that the accuracy of the predictions for shale gas flow improved. We believe that this technique will enrich the community’s understanding of fluid flows in shale gas reservoirs.

Decline Curves of a Vertical Well in Stress-Sensitive Reservoir

2013 ◽  
Vol 772 ◽  
pp. 781-788
Author(s):  
Zhang Zhang ◽  
Shun Li He ◽  
Hai Yong Zhang ◽  
Shao Yuan Mo ◽  
Shuai Li
Keyword(s):  
Pressure Drop ◽  
Analytical Solutions ◽  
Transient Behavior ◽  
Stress Sensitivity ◽  
Variable Pressure ◽  
Well Testing ◽  
Type Curves ◽  
Vertical Well ◽  
Constant Rate ◽  
Decline Curves

Stress-sensitivity effects have been recognized to have impact on the pressure/rate transient behavior of wells in several reservoirs. Although the effects of stress-sensitivity have been considered in well testing theory in the past thirty years, little has been done to determine their influence on rate decline behavior. This paper presents a single phase flow model considering stress-sensitive formation permeability to investigate the characteristic of production rate decline of a vertical well. The stress-sensitive permeability is considered as an exponential form. The permeability changes with pressure drop are described by a permeability modulus. By introducing two pseudo functions, the equations of the mathematical model are linearized and approximate semi-analytical solutions are obtained. The analytical solutions are carefully verified through numerical simulation. Two sets of new decline type curves are diagramed on a log-log plot for constant rate case and constant bottomhole pressure case respectively. The influence of stress-sensitive permeability on decline curves are analyzed and compared. From this work, we recognized that the rate decline characteristics of stress-sensitive reservoir under constant rate and constant bottomhole producing condition are different. New analysis method should be developed to analyze field variable rate/variable pressure drop data.

scholarly journals Characteristics of a non-circulating transient flow during gas invasion in the underbalanced drilling process

2019 ◽  
Vol 23 (4) ◽  
pp. 2257-2264
Author(s):  
Na Wei ◽  
Ying-Feng Meng ◽  
An-Qi Liu ◽  
Hai-Tao Li ◽  
Lin Jiang ◽  
...  
Keyword(s):  
Multiphase Flow ◽  
Transient Flow ◽  
Mathematic Model ◽  
Simulation Method ◽  
Pressure Profile ◽  
Drilling Process ◽  
Transient Pressure ◽  
Underbalanced Drilling ◽  
Wellbore Flow ◽  
Gas Liquid Flow

The wellbore flow in a liquid-based underbalanced drilling process consists of a steady multiphase flow during normal drilling and a transient gas-liquid flow without mud-cycling. The theory of steady multiphase flow has been used to calculate the pressure profile of normal drilling. Therefore, it is vital to figure out how to calculate the transient pressure variation caused by formation fluid flow-ing into wellbore when the mud-cycling is stopped. In this paper, a numerical simulation method and a mathematic model are established to study the wellbore flow and to control pressure during the underbalanced drilling process with liquid-based mud. The results also shed a light on the hidden mechanism of this special flow.

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