A Novel Approach To Detect Interacting Behavior Between Hydraulic Fracture and Natural Fracture by Use of Semianalytical Pressure-Transient Model

SPE Journal ◽  
2017 ◽  
Vol 22 (06) ◽  
pp. 1834-1855 ◽  
Author(s):  
Cong Xiao ◽  
Leng Tian ◽  
Yayun Zhang ◽  
Tengfei Hou ◽  
Yaokun Yang ◽  
...  
Keyword(s):  
Flow Regime ◽  
Hydraulic Fracture ◽  
Radial Flow ◽  
Natural Fracture ◽  
Dual Porosity ◽  
Horizontal Distance ◽  
Fracture System ◽  
Transient Model ◽  
Pressure Transient ◽  
Transient Characteristics

Summary The detection of interacting behavior between the hydraulic fracture (HF) and the natural fracture (NF) is of significance to accurately and efficiently characterize an underground complex-fracture system induced by hydraulic-fracturing technology. This work develops a semianalytical pressure-transient model in the Laplace domain to detect interacting behavior between HF and NF depending on pressure-transient characteristics. Our results have shown that no matter what the flow state (compressible or incompressible flow) within a hydraulically induced fracture system, we can easily detect interacting behavior between HF and NF depending on whether the “dip” shape occurs at the formation radial-flow regime. Referring to sensitivity analysis, distance between NF and well, horizontal distance between NF and HF, and NF length are the three most sensitive factors to detect fracture-interacting behavior. Depending on interference analysis, although the pressure-transient characteristics of a pseudosteady-state dual-porosity model can interfere with our proposed methodology, the difference between our model and a pseudosteady-state dual-porosity system lies in whether the value of the horizontal line of dimensionless pressure derivative is equal to 0.5 at the formation radial-flow regime. Our work obtains some innovative insights into detecting fracture-interacting behavior, and the valuable results can provide significant guidance for refracturing operations and fracture detection in an underground fracture system.

scholarly journals Production performance analysis for horizontal wells in composite coal bed methane reservoir

2017 ◽  
Vol 35 (2) ◽  
pp. 194-217 ◽  
Author(s):  
Zhang Wei ◽  
Jiang Ruizhong ◽  
Xu Jianchun ◽  
Gao Yihua ◽  
Yang Yibo
Keyword(s):  
Performance Analysis ◽  
Flow Regime ◽  
Transient Analysis ◽  
Horizontal Well ◽  
Radial Flow ◽  
Production Performance ◽  
Coal Bed ◽  
Coal Bed Methane ◽  
Pressure Transient Analysis ◽  
Pressure Transient

In this paper, the mathematical model of production performance analysis for horizontal wells in composite coal bed methane reservoir is introduced. In this model, two regions with different formation parameters are distinguished, and multiple mechanisms are considered including desorption, diffusion, and viscous flow. Then the solution of horizontal well performance analysis model is obtained by using point source function method, Laplace transform, and Stehfest algorithm comprehensively. The solution of the proposed model is verified with previous work thoroughly. The pressure transient analysis for horizontal well when producing at a constant rate is obtained and discussed. At last, different flow regimes are divided based on pressure transient analysis curves. They are early wellbore storage period, skin factor period, first radial flow regime, transition regime, second radial flow regime, transfer regime, and late pseudo-radial flow regime. The effects of related parameters such as storativity ratio, transfer coefficient, adsorption coefficient, ratio of vertical permeability to horizontal permeability, skin factor, horizontal well position in vertical direction, and inner region radius are analyzed as well according to pressure transient analysis and rate transient analysis curves. The presented work in this paper can give a better understanding of coal bed methane production performance in composite reservoir.

scholarly journals A Semianalytical Two-Phase Imbibition Model in Dual-Porosity and Dual-Permeability Reservoirs

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Mengmeng Li ◽  
Gang Bi ◽  
Jie Zhan ◽  
Liangbin Dou ◽  
Hailong Xu
Keyword(s):  
Single Phase ◽  
Two Phase Flow ◽  
Transient Behavior ◽  
Dual Porosity ◽  
Test Model ◽  
Phase Flow ◽  
Fracture System ◽  
Two Phase ◽  
Pressure Transient ◽  
Water Imbibition

The pressure transient behavior of water injection well has been extensively investigated under single-phase flow conditions. However, when water is injected into formation, there are saturation gradients within the water flooded area. Additionally, water imbibition is essentially important for oil displacement in dual-porosity and dual-permeability (DPDP) reservoirs. In this work, a novel semianalytical two-phase flow DPDP well test model considering both saturation gradient and water imbibition has been developed. The model was solved by the Laplace transform finite difference method. Type curves were generated, and flow regimes were identified by the model. The model features and effect of parameters were analyzed. Results show that water imbibition reduces the advancing speed of water drive front in the fracture system and slows down the water cut raising rate and the expansion speed of the two-phase zone in the fracture system. Therefore, the fluid exchange between the fracture and matrix systems becomes more sufficient and more oil will be recovered from the DPDP reservoir. The shape of pressure curves is similar for the single-phase and two-phase flow DPDP model, but the position of the proposed model is above the curves of the single-phase model. Shape factor mainly influences the interporosity period of the pressure derivatives. Water imbibition has a major effect on the whole system radial flow period of the curves. The findings of this study can help for better understanding of the oil/water two-phase flow pressure transient behavior in DPDP reservoirs considering saturation gradients and water imbibition.

Case Study: 4D Coupled Reservoir/Geomechanics Simulation of a High-Pressure/High-Temperature Naturally Fractured Reservoir

SPE Journal ◽  
2018 ◽  
Vol 23 (05) ◽  
pp. 1518-1538 ◽  
Author(s):  
Xiangtong Yang ◽  
Yuanwei Pan ◽  
Wentong Fan ◽  
Yongjie Huang ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Hydraulic Fracture ◽  
Natural Fracture ◽  
Hydraulic Fractures ◽  
Fracture System ◽  
Fractured Reservoir ◽  
Natural Fractures ◽  
Well Integrity ◽  
3D Geomechanical Model ◽  
Naturally Fractured ◽  
Reservoir Geomechanics

Summary The Keshen Reservoir is a naturally fractured, deep, tight sandstone gas reservoir under high tectonic stress. Because the reservoir matrix is very tight, the natural-fracture system is the main pathway for gas production. Meanwhile, stimulation is still required for most production wells to provide production rates that sufficiently compensate for the high cost of drilling and completing wells to access this deep reservoir. Large depletion (and related stress change) was expected during the course of the production of the field. The dynamic response of the reservoir and related risks, such as reduction of fracture conductivity, fault reactivation, and casing failure, would compromise the long-term productivity of the reservoir. To quantify the dynamic response of the reservoir and related risks, a 4D reservoir/geomechanics simulation was conducted for Keshen Reservoir by following an integrated work flow. The work started from systematic laboratory fracture-conductivity tests performed with fractured cores to measure conductivity vs. confining stress for both natural fractures and hydraulic fractures (with proppant placed in the fractures of the core samples). Natural-fracture modeling was conducted to generate a discrete-fracture network (DFN) to delineate spatial distribution of the natural-fracture system. In addition, hydraulic-fracture modeling was conducted to delineate the geometry of the hydraulic-fracture system for the stimulated wells. Then, a 3D geomechanical model was constructed by integrating geological, petrophysical, and geomechanical data, and both the DFN and hydraulic-fracture system were incorporated into the 3D geomechanical model. A 4D reservoir/geomechanics simulation was conducted through coupling with a reservoir simulator to predict variations of stress and strain of rock matrix as well as natural fractures and hydraulic fractures during field production. At each study-well location, a near-wellbore model was extracted from the full-field model, and casing and cement were installed to evaluate well integrity during production. The 4D reservoir/geomechanics simulation revealed that there would be a large reduction of conductivity for both natural fractures and hydraulic fractures, and some fractures with certain dip/dip azimuth will be reactivated during the course of field production. The induced-stress change will also compromise well integrity for those poorly cemented wellbores. The field-development plan must consider all these risks to ensure sustainable long-term production. The paper presents a 4D coupled geomechanics/reservoir-simulation study applied to a high-pressure/high-temperature (HP/HT) naturally fractured reservoir, which has rarely been published previously. The study adapted several new techniques to quantify the mechanical response of both natural fractures and hydraulic fractures, such as using laboratory tests to measure stress sensitivity of natural fractures, integrating DFN and hydraulic-fracture systems into 4D geomechanics simulation, and evaluating well integrity on both the reservoir scale and the near-wellbore scale.

Pressure-Transient Analysis of a Well With an Inclined Hydraulic Fracture

2010 ◽  
Vol 13 (06) ◽  
pp. 845-860 ◽  
Author(s):  
Anh V. Dinh ◽  
Djebbar Tiab
Keyword(s):  
Flow Regime ◽  
Hydraulic Fracture ◽  
Transient Analysis ◽  
Hydraulic Fractures ◽  
Pressure Derivative ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Fracture Models ◽  
Infinite Conductivity ◽  
Conductivity Models

Summary Hydraulic fracturing is an important well-stimulation technique that has been widely used in the oil and gas industry. Most of the pressure-transient-analysis techniques to analyze pressure responses of fractured wells are based on the assumption that the fracture is either vertical or horizontal. However, a hydraulic fracture could be inclined with a nonzero angle with respect to the vertical direction. Field studies have shown that most hydraulic fractures are not perfectly vertical. Thus, for an inclined hydraulic fracture, the vertical-orientation assumption may lead to erroneous results in welltest analysis, especially when the inclination angle is significant. However, there are very few studies concerning pressure-transient analysis of inclined hydraulic fractures, and there is no applicable well-test-analysis procedure available for inclined fractures. The purpose of this study is to develop a technique, on the basis of the pressure-derivative concept, for interpreting pressuretransient tests in wells with an inclined hydraulic fracture. Detailed analysis of unsteady-state pressure behavior of a fully penetrating inclined fracture in an infinite-slab reservoir was provided. Both uniform-flux and infinite-conductivity models were considered. The study has shown that inclined-fracture pressure data exhibit flow regimes similar to those for vertical fractures. Those flow regimes are linear and pseudoradial flow for both uniform-flux and infinite-conductivity models. However, for the infinite-conductivity model, a biradial- (or elliptical) flow regime is also observed. In the case of a high formation-thickness/fracture-half-length ratio and high angle of inclination, both uniform-flux and infiniteconductivity inclined-fracture models exhibit an additional flow regime, called early radial (ER) flow in this paper. This ER-flow regime for an inclined hydraulic fracture has not been mentioned in the literature before. A type-curve-matching technique was developed in this study using both pressure and pressure-derivative curves. This typecurve-matching procedure can be used to obtain the following parameters: fracture half-length, inclination angle, formation permeability, and the pseudoskin factor. The results should be verified with other pressure plots such as the semilog plot of vs. t and the Δp-vs.-t1/2 plot. A set of type curves with associated data was also provided for uniform-flux and infinite-conductivity inclined- fracture models. Detailed explanations, tables, figures, and a numerical example are included in this paper.

scholarly journals Pressure Transient Analysis for Sandstone Reservoir by Using Saphir

2020 ◽  
pp. 17-24
Author(s):  
Hussein Al- Ali
Keyword(s):  
Flow Regime ◽  
Transient Analysis ◽  
Radial Flow ◽  
Stone Formation ◽  
Cross Flow ◽  
Reservoir Model ◽  
Pressure Transient Analysis ◽  
Pressure Transient ◽  
Flow Regime Transition ◽  
A Value

This work is discussed how to differentiate between two tricky models for sand stone formation by using the pressure transient analysis PTA for three Wells which are distributed in south, middle and north of X field. In the derivative curve these two models have the same sequence of flow regime which are by hump, first radial flow regime, transition hump and then late radial flow regime. The parameter Kappa (K) played the most important key to select the type of reservoir model and differentiate between the two models in PTA. In the middle and south of the field, this parameter has a value close to one at well no. Rt-16 & Rt-18, which means that the system behaves as dual porosity. On the other hand, Kappa has a value of around (0.74) in Rt-17 to represent a double permeability system but without cross flow between two layers due to the small value of Lamda.

scholarly journals Transient Pressure Analysis of Inclined Well in Continuous Triple-Porosity Reservoirs With Dual-Permeability Behavior

2020 ◽  
Vol 8 ◽  
Author(s):  
Sheng-Zhi Qi ◽  
Xiao-Hua Tan ◽  
Xiao-Ping Li ◽  
Zhan Meng ◽  
You-Jie Xu ◽  
...  
Keyword(s):  
Radial Flow ◽  
Integral Transform ◽  
Flow Regimes ◽  
Response Characteristic ◽  
Flow Coefficient ◽  
Fracture System ◽  
Inversion Algorithm ◽  
Transient Pressure ◽  
Pressure Derivative ◽  
Pressure Transient

Inclined wells has recently been adopted to develop fractured-vuggy carbonate hydrocarbon reservoirs (FVCHRs) composed by matrix, fracture and vug system. Therefore, it is significant for us to describe pressure transient of inclined well for FVCHRs. In this paper, it is assumed that vug and fracture system connect with wellbore, and inter-porosity flow from vug to fracture system appears. Therefore, the pressure transient responses model of inclined well with triple-porosity dual-permeability behavior was built. The model is solved by employing Laplace integral transform and finite cosine Fourier transform. Real-domain solution of the model is obtained by Stehfest inversion algorithm. On the basis model of the published paper, the solution of the simplified model of this paper was validated with horizontal and vertical well of FVCHRs with triple-porosity dual-permeability behavior, and results reach a good agreement. Type curve, according to pressure derivative curve characteristic, can be divided into eight flow regimes, which includes wellbore storage, skin reflect, early vertical radial flow, top and bottom boundary reflection, linear flow, inter-porosity flow from vug to fracture, inter-porosity from matrix to vug and fracture and pseudo-radial flow regimes. The influence of some vital parameters (inclination angle, inter-porosity flow coefficient, well length and permeability ratio etc.) on dimensionless pressure and its derivative curves are discussed in detail. The presented model can be used to understand pressure transient response characteristic of inclined wells in FVCHRs with dual-permeability behavior.

Generating 3D Permeability Map of Fracture Networks Using Well, Outcrop, and Pressure-Transient Data

2011 ◽  
Vol 14 (02) ◽  
pp. 215-224 ◽  
Author(s):  
A.. Jafari ◽  
T.. Babadagli
Keyword(s):  
Fracture Network ◽  
Natural Fracture ◽  
Fracture System ◽  
Well Test ◽  
Fracture Networks ◽  
Statistical Parameters ◽  
Pressure Transient ◽  
Fractal Properties ◽  
2D Data ◽  
3D Fracture Network

Summary Well-log and core information, seismic surveys, outcrop studies, and pressure-transient tests are usually insufficient to generate representative 3D fracture-network maps individually. Any combination of these sources of data could potentially be used for accurate preparation of static models. Our previous attempts showed that there exists a strong correlation between the statistical and fractal parameters of 2D fracture networks and their permeability (Jafari and Babadagli 2009). We extend this work to fracture-network permeability estimation using the statistical and fractal properties data conditioned to well-test information. For this purpose, 3D fracture models of 19 natural-fracture patterns with all known fracture-network parameters were generated initially. It is assumed that 2D fracture traces on the top of these models and 1D data from imaginary wells that penetrated the whole thickness of the cubic models were available, as well as pressure-transient tests of different kinds. The 1D and 2D data include statistical parameters and fractal characteristics of different features of the fracture system. Next, the permeability of each 3D fracture-network model was measured and then converted to a grid-based permeability map for drawdown well-test simulations using commercial software packages. Finally, an extensive multivariable-regression analysis (MRA) using the statistical and fractal properties and well-test permeability as independent variables was performed to obtain a correlation for equivalent fracture-network permeability. The equations were derived using different natural-fracture-network patterns. The cases requiring well (logs and cores) and reservoir (pressure-transient tests) data were identified. It was found that an equation honoring all types of data [i.e., outcrop (2D), wellbore data (1D), and welltest analysis (3D)] can accurately predict the actual permeability of the fracture system. For certain fracture-network types, reliable correlations can be obtained without 2D data, which are relatively difficult to obtain. These types of patterns were identified.

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