Constant-pressure well test analysis of finite-conductivity hydraulically fractured gas wells influenced by non-Darcy flow effects

2006 ◽  
Vol 53 (3-4) ◽  
pp. 225-238 ◽  
Author(s):  
Ibrahim Sami Nashawi
Keyword(s):  
Constant Pressure ◽  
Darcy Flow ◽  
Finite Conductivity ◽  
Well Test ◽  
Gas Wells ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Flow Effects

Well Test Analysis for a Well in a Constant Pressure Square

1972 ◽  
Author(s):  
Anil Kumar ◽  
H. J. Ramey
Keyword(s):  
Constant Pressure ◽  
Outer Boundary ◽  
Initial Pressure ◽  
Fluid Injection ◽  
Well Test ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Water Influx ◽  
Mean Pressure ◽  
Well Tests

Abstract Very little information exists for analyzing well tests wherein a part of the drainage boundary is under pressure support from water influx or fluid injection. An idealization is the behavior of a well in the center of a square whose outer boundary remains at constant pressure. A study of this system indicated important differences from the behavior of a well in a closed outer boundary square, the conventional system. At infinite shut in, the constant- pressure boundary case well will reach the initial pressure of the system, rather than a mean pressure resulting from depletion. But it is possible to compute the mean pressure in the constant-pressure case at any time during shut in. Interpretative graphs for analyzing drawdown and buildup pressures are presented and discussed. This case is also of interest in analysis of well tests obtained from developed five-spot fluid injection patterns. Introduction Well-test analysis has become a widely used tool for reservoir engineers in the last twenty years. The initial theory was reported by Horner1 for unsteady flow of single phase fluids of small but constant compressibility to a well producing at a constant rate in -infinite and closed boundary reservoirs. Extension of the theory to the finite reservoir case involves specification of the outer boundary condition. The two most commonly observed conditions are: (1) no flow at the outer boundary corresponding to a closed or depletion reservoir, and (2) constant pressure at the outer boundary corresponding to complete water-drive.

Similar Constructive Method of Solution for the Nonlinear Percolation Model in Composite Reservoir

2014 ◽  
Vol 670-671 ◽  
pp. 678-682
Author(s):  
Feng Jiu Zhang ◽  
Xi Tao Bao ◽  
Shun Chu Li ◽  
Dong Dong Gui ◽  
Xiao Xu Dong
Keyword(s):  
Constant Pressure ◽  
Outer Boundary ◽  
Percolation Model ◽  
Constructive Method ◽  
Well Test ◽  
Analysis Software ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Method Of Solution ◽  
Quadratic Gradient

This paper presents a percolation model for the composite reservoir, in which quadratic-gradient effect, well-bore storage, effective radius and three types of outer boundary conditions: constant pressure boundary, closed boundary and infinity boundary are considered. With Laplace transformation, the percolation model was linearized by the substitution of variables and obtained a boundary value problem of the composite modified zero-order Bessel equation. Using the Similar Constructive Method this method, we can gain the distributions of dimensionless reservoir pressure for the composite reservoirs in Laplace space. The similar structures of the solutions are convenient for analyzing the influence of reservoir parameters on pressure and providing significant convenience to the programming of well-test analysis software.

Transient Rate Decline Analysis for Wells Produced at Constant Pressure

1981 ◽  
Vol 21 (01) ◽  
pp. 98-104 ◽  
Author(s):  
C.A. Ehlig-Economides ◽  
H.J. Ramey
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Constant Pressure ◽  
Well Test ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Type Curve ◽  
Type Curves ◽  
Constant Rate ◽  
Cumulative Production

Abstract Although constant-rate production is assumed in the development of conventional well test analysis methods, constant-pressure production conditions are not uncommon. Conditions under which constant-pressure flow is maintained at a well include production into a constant-pressure separator or pipeline, steam production into a backpressured turbine, or open flow to the atmosphere.To perform conventional well test analysis on such wells, one common procedure is to flow the well at a constant rate for several days before performing the test. This procedure is not always effective, and often the delay could be avoided by performing transient rate tests instead. Practical methods for transient rate analysis of wells produced at constant pressure are presented in this paper. The most important test is the analysis of the rate response to a step change in producing pressure. This test allows type-curve analysis of the transient rate response without the complication of wellbore storage effects. Reservoir permeability, porosity, and the wellbore skin factor can be determined from the type-curve match. The reservoir limit test is also important. Exponential rate decline can be analyzed to determine the drainage area of a well and the shape factor.The effect of the pressure drop in the wellbore due to flowing friction is investigated. Constant wellhead-pressure flow causes a variable pressure at the sandface because the pressure drop from flowing friction is dependent on the transient rate. Finally, for testing of new wells, the effect of a limited initial flow rate due to critical flow phenomena is examined. Introduction Fundamental considerations suggest that conventional pressure drawdown and buildup analysis methods developed for constant-rate production should not be appropriate for a well produced at a constant pressure. However, a well produced at a constant pressure exhibits a transient rate decline which can be analyzed using techniques analogous to the methods for constant-rate flow. In this paper, analytical solutions for the transient rate decline for wells produced at constant pressure are used to determine practical well test analysis methods.Many of the basic analytical solutions for transient rate decline have been available for some time. The first solutions were published by Moore et al. and Hurst. Results were presented in graphical form for bounded and unbounded reservoirs in which the flow was radial and the single-phase fluid was slightly compressible. Tables of dimensionless flow rate vs. dimensionless time were provided later by Ferris et al. for the unbounded system and by Tsarevich and Kuranov for the closed-boundary circular reservoir. Tsarevich and Kuranov also provided tabulated solutions for the cumulative production from a closed-boundary reservoir. Van Everdingen and Hurst presented solutions and tables of the cumulative production for constant-pressure production. Fetkovich developed log-log type curves for transient rate vs. sine in the closed-boundary circular reservoir. Type curves for rate decline in closed-boundary reservoirs with pressure-sensitive rock and fluid properties were developed by Samaniego and Cinco. A method for determining the skin effect was given by Earlougher. Type curves for analysis of the transient rate response when the well penetrates a fracture were developed by Prats et al. and Locke and Sawyer. SPEJ P. 98^

scholarly journals A New Approach for Well Test Analysis of Wells with Finite Conductivity Fractures.

2001 ◽  
Vol 44 (1) ◽  
pp. 1-10
Author(s):  
R. A. ALMEHAIDEB ◽  
J. H. ABOU-KASSEM ◽  
Mohammed E. OSMAN
Keyword(s):  
Finite Conductivity ◽  
Well Test ◽  
Well Test Analysis ◽  
Test Analysis ◽  
New Approach

scholarly journals Bilinear pressure diffusion and termination of bilinear flow in a vertically fractured well injecting at constant pressure

2020 ◽  
Author(s):  
Patricio-Ignacio Pérez D. ◽  
Adrián-Enrique Ortiz R. ◽  
Ernesto Meneses Rioseco
Keyword(s):  
Hydraulic Conductivity ◽  
Flow Regime ◽  
Flow Rate ◽  
Constant Pressure ◽  
Well Test ◽  
High Fracture ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Fracture Length ◽  
Fourth Root

Abstract. This work studies intensively the flow in fractures with finite hydraulic conductivity intersected by a well injecting/producing at constant pressure. Previous investigations showed that for a certain time the reciprocal of flow rate is proportional to the fourth root of time, which is characteristic of the flow regime known as bilinear flow. Using a 2D numerical model, we demonstrated that during the bilinear flow regime the transient propagation of isobars along the fracture is proportional to the fourth root of time. Moreover, we present relations to calculate the termination time of bilinear flow under constant injection or production well pressure, as well as, an expression for the bilinear hydraulic diffusivity of fractures with finite hydraulic conductivity. To determine the termination of bilinear flow regime, two different methods were used: (a) numerically measuring the transient of flow rate in the well and (b) analyzing the propagation of isobars along the fracture. Numerical results show that for low fracture conductivities the transition from bilinear flow to another flow regime occurs before the pressure front reaches the fracture tip and for high fracture conductivities it occurs when the pressure front arrives at the fracture tip. Hence, this work complements and advances previous research on the interpretation and evaluation of well test analysis under different reservoir conditions. Our results aim at improving the understanding of the hydraulic diffusion in fractured geologic media and as a result they can be utilized for the interpretation of hydraulic tests, for example to estimate the fracture length.

Well-Test Analysis for a Well in a Constant-Pressure Square

1974 ◽  
Vol 14 (02) ◽  
pp. 107-116 ◽  
Author(s):  
Anil Kumar ◽  
Henry J. Ramey
Keyword(s):  
Constant Pressure ◽  
Outer Boundary ◽  
Fluid Injection ◽  
Well Test ◽  
Well Test Analysis ◽  
Test Analysis ◽  
Mean Pressure ◽  
Long Time ◽  
Single Well ◽  
Well Tests

Abstract Very little information exists for analyzing well tests wherein a part of the drainage boundary is under pressure support from water influx or fluid injection. An idealization is the behavior of a well in the center of a square whose outer boundary remains at constant pressure. A study of this system indicated important differences from the behavior of a well in a square with a closed outer boundary, the conventional system. At infinite shut-in, the well with a constant-pressure boundary will reach the initial pressure of the system, rather than a mean pressure resulting from depletion. It is possible to compute the mean pressure in the constant-pressure case at any time during shut-in. Interpretative graphs for analyzing drawdown and buildup pressures are presented and discussed. This case is also of interest in analyzing well tests obtained from developed five-spot fluid-injection patterns. Introduction Moore at. first demonstrated the application of transient flow theory to individual well behavior in 1931. Classic studies by Muskat, Elkins, and Arps in the 1930's and 1940's set the stage for two important papers in 1950 that clearly elucidated the basics of modern well-test analysis. One paper by Horner 5 summarized methods for analyzing transient pressure data from wells in infinite reservoirs (new wells in large reservoirs), and a well in a closed, circular reservoir under depletion (fully developed fields). The second paper by Miller, Dyes, and Hutchinsons considered two cases for wells assumed to have produced a long time before shut-in for pressure buildup. One case assumed a closed circular drainage boundary, and the other case assumed a circular drainage boundary at constant pressure. The former would represent annual well tests for fully developed fields, and the latter would represent wells under full water drive in single-well reservoirs. Since 1950, several hundred papers and a monograph have developed the behavior of a constant-rate well in a closed drainage shape of almost any geometry. Key in this development was a classic study by Matthews, Brons, and Hazebroek. The constant-pressure outer-boundary drainage region problem introduced by Miller-Dyes-Hutchinson was reviewed by Perrine in 1955, discussed by Hazekoek el al. in 1958 in connection with five-spot injection patterns, and mentioned briefly by Dietz in 1965. The only other studies dealing with water-drive conditions (constant-pressure outer boundaries) appear in Ref. 7 (Page 44) and in papers by Earlougher et al., published in 1968. It is clear that this case was eitherconsidered totally unimportant, orstudiously avoided. Almost all effort was expended on studying closed outer boundary (depletion) systems.Another problem concerned the conventional assumptions involved in developing well-test analysis method. Even for the common closed (depletion) systems, field applications raised the question of the importance of assumptions. Homer method of graphing assumed the well had been produced a short time, whereas the Miller-Dyes-Hutchinson method assumed that production was long enough to reach pseudosteady state -a long time in many cases. Engineers involved in applications were further confused by differences in methods, as well as by the importance of the assumptions required for analytical solutions that established welltest methods. Recently, Ramey and Cobb showed that an empirical approach could be used to avoid assumptions (which were sufficient but unnecessary) inherent in many previous analytical studies. It was decided to apply this method to the limiting case of a well in a full-water-drive, single-well reservoir - a well in a constant-pressure square. This case is a rarity not often seen in practice. It is closely approached by either an injector or a producer in a developed fluid-injection pattern, by a single injector in an aquifer gas-injection storage test, or by some single-well reservoirs in extensive aquifers.The main point is that a well in a constant-pressure square sets a limiting condition similar to a full water drive. The more common case of a well in a partial-water-drive reservoir should lie between this behavior and that of a closed square. SPEJ P. 107^

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