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Es Adewole - One of the best experts on this subject based on the ideXlab platform.
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Theoretical Breakthrough Time of Horizontal Wells Subject to External Fluid Drive in a Layered Reservoir with Varying Architecture; Part V: Letter ‘E’ Architecture
All Days, 2014Co-Authors: Es AdewoleAbstract:Abstract When a vertically-stacked two-Layered Reservoir system with an architecture akin to letter ‘E’ is encountered in practice, the right strategy for well completion, overall Reservoir characterization and selection of optimum production rates, especially when the contiguous layers are exposed to external fluid influences, become a serious challenge. This paper compiles the necessary equations required to be solved to obtain theoretical external fluid breakthrough time for different Reservoir layers, well choices and external fluid drives that may influence clean oil production in a two-Layered Reservoir with a letter ‘E’ architecture. Results show that fiftteen (15) different boundary variations are possible each for normal and inverted architecture. Among these variations only two (2) may have the maximum six (6) similar external boundary combinations of constant-pressure. There are two (2) mandatory infinite-acting external boundaries in each architecture, which can neither be sealed nor constant-pressured. Edge, top and bottom external fluid drives are possible in any architecture. For the top layer, only one (1) top and one (1) edge external fluid drive separately is possible for crossflow interface. But for the bottom layer, one (1) edge and one (1) bottom drive separately is possible both for crossflow layers. For no-crossflow interface, only the top layer can be subject to top external fluid drive and only the bottom layer can be subject to a bottom external fluid drive, but both layers can be subject to one (1) edge drive each. Theoretical breakthrough times derived are directly proportional to Reservoir extents in two (2) directions and inversely with Reservoir layers diffusivity. For single external fluid drive source, only the Reservoir length exposed to the drive directly affects breakthrough time. Layered Reservoirs with crossflow interface are characterized by functions v(i) and v(z), but do not form equations to be solved alone but in combination with a function describing associated external drive. When two layers are contributing to flow through the interface, breakthrough times are identified by the function iv(z) and any other function describing associated external fluid drive.
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Mathematical Formulation of Interference Tests Analyses Procedure for Horizontal and Vertical Wells Both in a Laterally Infinite Layered Reservoir
Petroleum Science and Technology, 2013Co-Authors: Es AdewoleAbstract:Analytical procedures, based on dimensionless pressures and derivative distribution of different combinations of vertical and horizontal wells in the layers of a crossflow Layered Reservoir, are derived. Results show that analytical expressions for calculating fluid and Reservoir properties depends on the type of well used as active well during interference test. If the wells are completed within the same layer, only regional permeability between the wells will determine the rate of interference apart from the rate of withdrawal from the active well. In this case, horizontal wells produce stronger interference than a vertical well given the same anisotropy and rate history. If the wells are located in different layers, then the degree of crossflow between the layers becomes the most important factor affecting interference.
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PRESSURE DISTRIBUTION IN A Layered Reservoir WITH GAS-CAP AND BOTTOM WATER
Nigerian Journal of Technology, 2012Co-Authors: Af Owolabi, Oa Olafuyi, Es AdewoleAbstract:Oil production from a Layered Reservoir with a top gas cap and bottom water acting simultaneously poses serious challenges of rate and pressure maintenance. To achieve clean oil production both rates and pressures regimes have to be chosen carefully according to available to avert production of unwanted external fluids. Furthermore, well tests analyses of pressure data would require that flow from each layer is adequately quantified and delineated. For layers with crossflow interface isolating each layer through a test analysis is additional challenge. If the layers contain oil of different properties, well completion strategy has to be specially crafted to achieve optimal individual layer production performance. It is with a view to addressing these challenges that this study becomes absolutely necessary. In this study, dimensionless pressure and dimensionless pressure derivatives are derived for each layer of a two Layered Reservoir, both drained through one vertical wellbore. The difference in flow behavior of the different layers is normalized, for crossflow layers, through a dimensionless time frame. The normalization enabled the crossflow layer to be treated as one enlarged Reservoir and was utilized to discriminate flow from layers, no matter the choice of well completion and disparity in layer fluid properties. Flow times considered is elaborate and ranged from very early to early and late time, large enough for at least one of the external boundaries to be felt in a test period. Because the external boundaries impose a steady state, the emergence of steady state is considered as end of flow of clean oil in our computations. The characteristic signatures of the log-log plot of dimensionless pressures and pressure derivatives for early time and late flow periods were then used to characterize the Reservoir system. It is revealed that time for clean oil production is longer for larger and thicker layers for constant production rate history. Furthermore, a flattening and a collapse to zero trends are observed on dimensionless pressure and dimensionless pressure derivative plots, respectively, when the effects of the top and/or bottom boundaries are felt. When a permeable interface is felt, similar trends are observed but there is cessation shortly afterwards depending on the degree of interlayer crossflow. Furthermore, it was noticed that perforation location does not seriously affect well productivities, especially at early times. Finally, only fluid ratios is recommended as adequate to reveal which of the external fluids accidentally reaches the wellbore during oil production, since each of the external fluids is capable of manifesting steady-state behavior.
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compilation of instantaneous source functions for varying architecture of a Layered Reservoir with mixed boundaries and horizontal well completion part iv normal and inverted letter h and h architecture
Journal of the Nigerian Association of Mathematical Physics, 2010Co-Authors: Es Adewole, Oa OlafuyiAbstract:Instantaneous source functions have been compiled and tabulated for both normal and inverted two-Layered Reservoir of letter ‘e’ architecture. The source functions describe fluid flow in horizontal wells drilled in each layer. Possibility of the existence of all flow periods was considered for each well. Results obtained show that letter ‘e’ architecture yields thirty-two (32) different models with different variations of its five external boundaries, which may be sealed or constant-pressured. The inverted architecture also yields thirty-two (32) different models of varying sealing and constant-pressure boundaries. Vertical inversions turns top of the architecture bottom and bottom top, while horizontal inversion merely turns the top of a horizontal well bottom and bottom top. In other words, all the forms (normal and inverted) of letter ‘e’ architecture will collectively yield one hundred and twenty-eight (128) different models with different variations of sealing and constant-pressure boundaries. Finally, any form of the letter ‘e’ architecture has one mandatory ‘infinitely far away’ external boundary.
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compilation of instantaneous source functions for varying architecture of a Layered Reservoir with mixed boundaries and horizontal well completion part iii b shaped architecture with vertical well in the upper layer
Journal of the Nigerian Association of Mathematical Physics, 2010Co-Authors: Es AdewoleAbstract:Two-Layered Reservoirs with a vertical well in the top layer and with letter ‘B’ architecture, is encountered very frequently in practice. Instantaneous source functions, which can be utilized in constructing pressure distributions for the purpose of fully characterizing such Reservoirs, are derived in this paper. Results show that sixty-four (64) different variations are possible, as a result of six (6) different external boundaries, which may be considered sealed or constant-pressured. With the interface also considered as a constant-pressure boundary, it is observed that the more the number of constant-pressure external boundaries, the fewer the source functions that could be written and vice-versa. Furthermore, only sources of the kind I(i) can be written for the vertical wells while sources of the kinds I(i), vi(i) and iii(i) are possible for only the x-axes of the horizontal well layer.
Luis C. Ayestaran - One of the best experts on this subject based on the ideXlab platform.
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Interpretation of a Pulse Test in a Layered Reservoir
SPE Formation Evaluation, 1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:Summary. An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore field in Abu Dhabi. The interpretation of three pulses yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a two-layer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. We conclude that conventional pulse-test interpretation methods cannot be satisfactorily applied to the pressure response in a two-layer system. Introduction An interwell pressure test results in transmissibility (kh/mu) and storativity (phi hct) estimates between the wells. Until recently, the analytical interpretation of a pulse or interference test was carried out with a single-layer Reservoir model. It is very rare to have Reservoirs that comprise only a single homogeneous layer. In a multilayer system, interpretation of an interwell pressure test requires a numerical simulator or analytical solutions (type curves) for a model formulated for more than one layer. An interwell test was designed, implemented, and interpreted for the Arab zones of an offshore Abu Dhabi oil field. Pulses of 18-hour duration were instigated in the active well. The first three pairs of time lags and pressure amplitudes were interpreted with conventional pulse-test analysis methods. All three pairs gave different answers for transmissibility and storativity, which should not be the case if the single-layer interpretation model is applicable. The Reservoir connecting the two wells has two distinct permeable layers, so the pulse responses were interpreted with a two-layer analytical model. The two-layer analytical model generates a family of type curves for the pressure response in the observation well that depend on three main parameters: K, which quantifies the permeability contrast between the two layers; w, which depends on the layer permeability contrast between the two layers; w, which depends on the layer storativities; and lambda, which is an interlayer crossflow parameter. This paper demonstrates the successful use of a two-layer analytical model for the interpretation of an interwell test. It also shows how a numerical simulator was used to calculate the pressure response from a third producing well that was interfering with the pressure response in the observation well. The interpretation gives pressure response in the observation well. The interpretation gives the estimates of transmissibility and storativity for each layer. A sensitivity analysis for k, w, and lambda indicates that the pressure-pulse response is not sensitive to interlayer vertical pressure-pulse response is not sensitive to interlayer vertical permeability but is influenced by contrasts in layer permeability and permeability but is influenced by contrasts in layer permeability and porosity. porosity. Background The analytical principles of design and interpretation of interwell pressure tests (pulse or interference) are well known, and some of pressure tests (pulse or interference) are well known, and some of these techniques are given in Refs. 1 through 5. Most of the literature uses the line-source solution to the diffusivity equation as the building block for designing and interpreting interwell pulse and interference tests. The background pressure/time response need not be known to interpret the pulse test but is necessary to interpret the interference test. For heterogeneous Reservoirs, the use of a numerical Reservoir simulator has been recommended to interpret interwell pressure tests. Recently, analytical models have been made available to interpret such tests in Layered Reservoirs. We used Bourdet's model to interpret the interwell test presented in this paper. Although the principles of these tests are extensively published, few successful interpretations are documented. One documented case history is of interwell pressure tests done with conventional analytical interference- and pulse-test methods for China's Shengloil field. A successful application of interwell pressure tests was recently presented for a fractured Reservoir. We used line- source-solution methods presented for a fractured Reservoir. We used line- source-solution methods to design the interwell pressure test presented here as a pulse test. Our results, however, are interpreted as an interference test with a type curve based on a two-layer analytical model, after the interference from a third well was accounted for with a numerical Reservoir simulator. Test Design Kamal and Brigham's charts-were used to perform the design and sensitivity analysis for various pulse-cycle lengths, delta tc, and pulse ratios, F'p=(delta tp/delta tc). The decision to use a specific pulse ratio and cycle length was based on the pulse-response amplitude, and dimensionless time lag, t L/delta tc. Design runs were made for pulse ratios of 0.3, 0.4, 0.5, and 0.6, while cycle lengths (producing pulse + shut-in pulse) of 24 and 36 hours were used. Table 1 shows the Reservoir parameters used to design the test, and Table 2 gives the pulse-response amplitudes and the dimensionless time lags for odd and even pulses of the cycle lengths used. The total skin factor was taken as + 1 for both wells. The dimensionless wellbore storages, CD, for Wells 1 and 2 were estimated from a known wellbore volume of 660 bbl and an oil compressibility of 428 psi-1. The CD correction factors to the pressure amplitudes, taken from charts generated by Prats and Scott, were negligible for all pulses. From the pulse-test design results shown in Table 2, it is evident that a 36-hour cycle length and a 0.5 pulse ratio give the highest pressure amplitude in the observation well at reasonable lag times. pressure amplitude in the observation well at reasonable lag times. For shut-in and flowing pulses of 18 hours each, the amplitudes range from 3.1914 to 4.0632 psi. The design rate at the pulsing well was 1,000 STB/D. Fig. 1 shows the expected pulse response at Well 2 on the basis of the above design. Measurement This Reservoir of Arab zones is offshore Abu Dhabi. At the time of the test, three wells were completed. Wells 1 and 3 had been producing for about 2 months, while Well 2, the observation well, producing for about 2 months, while Well 2, the observation well, was yet to be put on-stream. The rate pulses were instigated in Well 1, but the production rate at Well 3 was not disturbed during the test. The observation well was filled with diesel to minimize wellbore storage, and a downhole electronic gauge was used to monitor the pressure response. Pressure recording began at Well 2 about 2 hours pressure response. Pressure recording began at Well 2 about 2 hours before Well 1 was shut in. This period should have been much longer to reveal the background pressure trend in Well 2 caused by production from Wells 1 and 3. production from Wells 1 and 3. If Well 2 were in a single-layer Reservoir, the data would have been analyzed with conventional pulse-test interpretation methods and the background pressure trend in the Reservoir would not have been required for the analysis. Fig. 2 shows the pulse response in Well 2 with the rate pulses implemented in Well 1. Table 3 and Figs. 3 through 5 show the measured pressure amplitudes and time lags. Pulse Interpretation Pulse Interpretation The following interpretation procedure was used to obtain a satisfactory match to the pulses. SPEFE P. 453
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Interpretation of a Pulse Test in a Layered Reservoir
Spe Formation Evaluation, 1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore oil field in Abu Dhabi. The interpretation of three pulses yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a twolayer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. This paper concludes that conventional pulse-test interpretation methods cannot be satisfactorily applied to the pressure response in a two-layer system.
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Interpretation of a pulse test in a Layered Reservoir
1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore field in Abu Dhabi. The interpretation of three yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a two-layer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. We conclude that conventional pulse-test interpretation methods cannot be satisfactorily applied to the presure response in a two-layer system
W. John Lee - One of the best experts on this subject based on the ideXlab platform.
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Characterizing Multi-Layered Reservoirs Using A New, Simple, Inexpensive and Environmentally Sensitive Pre-Production Well Test
All Days, 1996Co-Authors: Ahmed Aly, W. John LeeAbstract:Abstract This paper presents a simple, inexpensive, and environmentally sensitive method to characterize and model multi-layer Reservoirs with unequal initial pressures in individual layers. The testing techniques involve monitoring pressure data caused by crossflow between the layers prior to flow at the surface (pre-production well testing). When boundary effects are reached in the test, it is possible to estimate individual layer permeability, skin and drainage area. Also, as there is no production on the surface, the new well test is well suited for offshore wells or for testing wells in environmentally sensitive areas. Introduction All natural formations are vertically heterogeneous to some degree because of the stratification accompanying their depositional origin. The vertical sequence of deposits is frequently such that layers having good permeability alternate with layers having poor permeability. A sequence of sands interbedded with clay or shale is an example of such a formation. In many cases, we perforate wells simultaneously in two or more layers. The major drawback of the multiple-layer completion concept is that the origin of the produced fluid is generally unknown. As a result, it is difficult to apply Reservoir engineering principles to predict recovery and future performance under primary and enhanced recovery operations from each of the layers. Normally, we must determine the properties of the individual layers to improve the prediction of Reservoir behavior. Several studies have examined the wellbore response in multilayer Reservoirs. However, most of these studies examined wellbore response from a two-layer Reservoir with equal initial pressures. In this work, we expand the scope of study to investigate the wellbore response from multi-Layered Reservoirs (two-, three- and five-layers) with unequal initial pressures. We address the needs of the industry, especially in North Sea Reservoirs, for practical and easily applied methods to determine individual layer properties by modeling and analyzing the performance of multi-layer Reservoirs with unequal initial pressures. The first phase in Layered Reservoir studies dealt with the problem of commingled Reservoirs with equal initial pressures. The second phase included the effect of unequal initial layer pressures which Papadupolos studied first for Layered aquifers. Larsen presented a method for analyzing wellbore pressures prior to the start of production for a two-layer Reservoir, provided such data are available from the infinite-acting period. The method has the disadvantage that it requires estimates of the average permeability, porosity and compressibility for each individual layer. Also, this method can yield only an estimate of the average Reservoir properties and not individual layer properties. Kuchuk et al. presented generalized analytical solutions for commingled Reservoirs in which each Reservoir or layer can be at a different initial pressure or may have a different initial pressure distribution. Agarwal et al. presented a detailed study of the preproduction time period. The study showed that much information that has bearing on production-performance can be discerned by the observation of the pressure behavior during the pre-production time period. A number of approximate solutions were presented for analyzing well responses. Aly presented a complete study of the performance of commingled Reservoirs with unequal initial pressures. Aly et al. presented a new method for analyzing the PPWT pressure data from a two-layer, commingled Reservoir with unequal initial layer pressures to determine the individual layer properties. Aly et al. presented a detailed development of the mathematical model for multilayer Reservoirs with unequal initial pressures. Pre-Production Well Test Design The PPWT is performed early in the life of a Reservoir, when the information is most needed for planning production schedules and making economic decisions. Pre-production is the period after completion but before production of the well. Immediately after perforation, we position a pressure gauge above the top perforation to measure the pressure performance of the total system. The differential pressure between the layers causes cross flow from one layer to another which triggers the pressure signal. One important advantage of the preproduction well test is that there is no surface production during the test. Thus, the environmental impact caused by flaring oil or gas is eliminated. The pre-production well test needs only a pressure gauge above the top layer and the pre-production pressure data up to the late-transient region. The cost and the time are reduced substantially compared to the commercial "Layered Reservoir Test." The PPWT is well suited for offshore wells and for environmentally sensitive areas like the Gulf of Suez, as there is no production on surface during the test. Also, because this test is carried out very early in the life of the Reservoir, before the pipelines and facilities are ready, no production time is lost. Fig. 1 shows a sketch of the pre-production well test. A schedule for the test follows:Record the initial pressure of each layer using a wireline formation tester. P. 519
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Development of a New Theoretical Model for Three-Layered Reservoirs With Unequal. Initial Pressures
All Days, 1995Co-Authors: Aly Ahmed, W. John LeeAbstract:Abstract In this paper we present a new theoretical model for three-layer Reservoirs with unequal initial pressures. We developed a semianalytical simulator based on the developed model. The computational model proved to be much faster than a three-dimensional, finite-difference commercial simulator used to validate the analytical model. Also, the amount of information (spatial gridding) needed to run the model is much reduced. The analytical model allows each layer to have different layer properties, different boundary conditions, and different initial pressures. We used the semi-analytical simulator to perform a detailed study of the behavior of three-Layered Reservoirs during the "pre-production period." The pre-production period occurs early in the life of the Reservoir, after perforation but before any surface production and is caused by crossflow in the wellbore. The layer information obtained is very important for scheduling production and making economic decisions concerning the future of the wells. The pre-production well test requires no production on the surface during the test; thus the impact on the environment is negligible. The main objective of this work is to develop a qualitative approach to extract more information about the Reservoir from preproduction wellbore pressure, dimensionless pressure and dimensionless pressure derivative curves. More specifically, we studied the preproduction behavior of three-Layered Reservoirs. Effects of the ratio of flow capacity and storage in different layers were investigated. We found that the layers with highest and lowest permeabilities can be characterized with the logarithmic time derivative of pre-production pressures. A positive derivative indicates high permeability in the layer with the highest initial pressure, and a negative derivative indicates high permeability in the layer with low initial pressure. Also, the layer with the highest initial pressure will always flow into the wellbore whereas flow will always be from the wellbore into the layer with minimum initial pressure. As the sandface rates reach steady state, the three-layer system behaves like an equivalent single layer system. Thus, we can apply a single-layer model to analyze the late transient in high permeability Reservoirs. Introduction Most multi-Layered Reservoir models reported in the literature includes only two layers with equal initial pressures. In this paper, we extend modeling first to three-layer Reservoirs and provide the basis for n-layer Reservoirs. This work addresses the need for a practical and easily applied method to determine the individual layer properties. The first phase in Layered Reservoir studies dealt with the problem of commingled Reservoirs with equal initial pressures1–11. The second phase included the effect of unequal initial layer pressures which Papadupolos12 studied first for Layered aquifers. Larsen13 presented a method for analyzing wellbore pressures prior to the start of production for a two-layer Reservoir, provided such data are available from the infinite-acting period. The method has the disadvantage that it requires estimates of the average permeability, porosity and compressibility for each individual layer. Also, this method can yield only an estimate of the average Reservoir properties and not individual layer properties. Kuchuk et a1.14 presented generalized analytical solutions for commingled Reservoirs in which each Reservoir or layer can be at a different initial pressure or may have a different initial pressure distribution. Agarwal et a1.15 presented a detailed study of preproduction time period. The study showed that much information that has bearing on production performance can be discerned by the observation of the pressure behavior during the pre-production time period. A number of approximate solutions are presented for analyzing well responses. Aly16 and Aly et al.17 presented a complete study of the performance of commingled Reservoirs with unequal initial pressures. Aly and Lee18 presented a comprehensive semi-analytical simulator and verified it against cases from the literature. They also introduced the pre-production well test, PPWT. They presented a detailed procedure to show how to implement this test in the field and introduced analysis methods to determine the individual layer properties from the pre-production wellbore pressure.
Ryuzo Kaneda - One of the best experts on this subject based on the ideXlab platform.
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Interpretation of a Pulse Test in a Layered Reservoir
SPE Formation Evaluation, 1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:Summary. An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore field in Abu Dhabi. The interpretation of three pulses yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a two-layer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. We conclude that conventional pulse-test interpretation methods cannot be satisfactorily applied to the pressure response in a two-layer system. Introduction An interwell pressure test results in transmissibility (kh/mu) and storativity (phi hct) estimates between the wells. Until recently, the analytical interpretation of a pulse or interference test was carried out with a single-layer Reservoir model. It is very rare to have Reservoirs that comprise only a single homogeneous layer. In a multilayer system, interpretation of an interwell pressure test requires a numerical simulator or analytical solutions (type curves) for a model formulated for more than one layer. An interwell test was designed, implemented, and interpreted for the Arab zones of an offshore Abu Dhabi oil field. Pulses of 18-hour duration were instigated in the active well. The first three pairs of time lags and pressure amplitudes were interpreted with conventional pulse-test analysis methods. All three pairs gave different answers for transmissibility and storativity, which should not be the case if the single-layer interpretation model is applicable. The Reservoir connecting the two wells has two distinct permeable layers, so the pulse responses were interpreted with a two-layer analytical model. The two-layer analytical model generates a family of type curves for the pressure response in the observation well that depend on three main parameters: K, which quantifies the permeability contrast between the two layers; w, which depends on the layer permeability contrast between the two layers; w, which depends on the layer storativities; and lambda, which is an interlayer crossflow parameter. This paper demonstrates the successful use of a two-layer analytical model for the interpretation of an interwell test. It also shows how a numerical simulator was used to calculate the pressure response from a third producing well that was interfering with the pressure response in the observation well. The interpretation gives pressure response in the observation well. The interpretation gives the estimates of transmissibility and storativity for each layer. A sensitivity analysis for k, w, and lambda indicates that the pressure-pulse response is not sensitive to interlayer vertical pressure-pulse response is not sensitive to interlayer vertical permeability but is influenced by contrasts in layer permeability and permeability but is influenced by contrasts in layer permeability and porosity. porosity. Background The analytical principles of design and interpretation of interwell pressure tests (pulse or interference) are well known, and some of pressure tests (pulse or interference) are well known, and some of these techniques are given in Refs. 1 through 5. Most of the literature uses the line-source solution to the diffusivity equation as the building block for designing and interpreting interwell pulse and interference tests. The background pressure/time response need not be known to interpret the pulse test but is necessary to interpret the interference test. For heterogeneous Reservoirs, the use of a numerical Reservoir simulator has been recommended to interpret interwell pressure tests. Recently, analytical models have been made available to interpret such tests in Layered Reservoirs. We used Bourdet's model to interpret the interwell test presented in this paper. Although the principles of these tests are extensively published, few successful interpretations are documented. One documented case history is of interwell pressure tests done with conventional analytical interference- and pulse-test methods for China's Shengloil field. A successful application of interwell pressure tests was recently presented for a fractured Reservoir. We used line- source-solution methods presented for a fractured Reservoir. We used line- source-solution methods to design the interwell pressure test presented here as a pulse test. Our results, however, are interpreted as an interference test with a type curve based on a two-layer analytical model, after the interference from a third well was accounted for with a numerical Reservoir simulator. Test Design Kamal and Brigham's charts-were used to perform the design and sensitivity analysis for various pulse-cycle lengths, delta tc, and pulse ratios, F'p=(delta tp/delta tc). The decision to use a specific pulse ratio and cycle length was based on the pulse-response amplitude, and dimensionless time lag, t L/delta tc. Design runs were made for pulse ratios of 0.3, 0.4, 0.5, and 0.6, while cycle lengths (producing pulse + shut-in pulse) of 24 and 36 hours were used. Table 1 shows the Reservoir parameters used to design the test, and Table 2 gives the pulse-response amplitudes and the dimensionless time lags for odd and even pulses of the cycle lengths used. The total skin factor was taken as + 1 for both wells. The dimensionless wellbore storages, CD, for Wells 1 and 2 were estimated from a known wellbore volume of 660 bbl and an oil compressibility of 428 psi-1. The CD correction factors to the pressure amplitudes, taken from charts generated by Prats and Scott, were negligible for all pulses. From the pulse-test design results shown in Table 2, it is evident that a 36-hour cycle length and a 0.5 pulse ratio give the highest pressure amplitude in the observation well at reasonable lag times. pressure amplitude in the observation well at reasonable lag times. For shut-in and flowing pulses of 18 hours each, the amplitudes range from 3.1914 to 4.0632 psi. The design rate at the pulsing well was 1,000 STB/D. Fig. 1 shows the expected pulse response at Well 2 on the basis of the above design. Measurement This Reservoir of Arab zones is offshore Abu Dhabi. At the time of the test, three wells were completed. Wells 1 and 3 had been producing for about 2 months, while Well 2, the observation well, producing for about 2 months, while Well 2, the observation well, was yet to be put on-stream. The rate pulses were instigated in Well 1, but the production rate at Well 3 was not disturbed during the test. The observation well was filled with diesel to minimize wellbore storage, and a downhole electronic gauge was used to monitor the pressure response. Pressure recording began at Well 2 about 2 hours pressure response. Pressure recording began at Well 2 about 2 hours before Well 1 was shut in. This period should have been much longer to reveal the background pressure trend in Well 2 caused by production from Wells 1 and 3. production from Wells 1 and 3. If Well 2 were in a single-layer Reservoir, the data would have been analyzed with conventional pulse-test interpretation methods and the background pressure trend in the Reservoir would not have been required for the analysis. Fig. 2 shows the pulse response in Well 2 with the rate pulses implemented in Well 1. Table 3 and Figs. 3 through 5 show the measured pressure amplitudes and time lags. Pulse Interpretation Pulse Interpretation The following interpretation procedure was used to obtain a satisfactory match to the pulses. SPEFE P. 453
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Interpretation of a Pulse Test in a Layered Reservoir
Spe Formation Evaluation, 1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore oil field in Abu Dhabi. The interpretation of three pulses yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a twolayer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. This paper concludes that conventional pulse-test interpretation methods cannot be satisfactorily applied to the pressure response in a two-layer system.
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Interpretation of a pulse test in a Layered Reservoir
1991Co-Authors: Ryuzo Kaneda, Jawaid Saeedi, Luis C. AyestaranAbstract:An interwell pressure test, designed and implemented as a pulse test, was performed in the Arab zones of an offshore field in Abu Dhabi. The interpretation of three yielded inconsistent results for transmissibility and storativity. The pressure response data were interpreted with a two-layer analytical model after a numerical simulator was used to modify the pressure response for the interference from a third well. The two-layer analytical model provided an excellent match of the modified pressure response. We conclude that conventional pulse-test interpretation methods cannot be satisfactorily applied to the presure response in a two-layer system
E. Steve Adewole - One of the best experts on this subject based on the ideXlab platform.
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Theoretical Dimensionless Breakthrough Time of a Horizontal Well in a Vertically-Stacked Two-Layered Reservoir System with Varying Architecture Part I: Letter ‘B’ Architecture, Edge Water Drive Mechanism
Advanced Materials Research, 2011Co-Authors: E. Steve AdewoleAbstract:When a Reservoir experiences water influx, the actual source of the water often cannot be ascertained with precision. Thus well work over measures to minimize the water may not be easy to fashion. Bottom water encroaches through the bottom of the Reservoir and rises vertically, appearing in all the wells in the field at the same time, if the wells experience the same production histories. This further makes work over difficult, more so, if there are other external fluid influences akin to a top gas. However, if the arrival time is known, then factors affecting bottom water movement, with or without any other contiguous top gas, may be studied with a view to fashioning an effective work over to mitigate premature water arrival into the well. Horizontal wells are already known to delay encroaching water breakthrough time. For a cross flow Layered Reservoir completed with a horizontal well in each layer, flow dynamics will certainly be different from a single layer Reservoir due to differences in individual layer, layers fluid, wellbore and interface properties and rate histories. In this paper, theoretical expressions for predicting dimensionless breakthrough times of horizontal wells in a two Layered Reservoir of architecture like letter ‘B’, experiencing bottom water drive mechanism of different patterns, with or without a top gas, are derived. The theoretical breakthrough times are based on dimensionless pressure and dimensionless pressure derivative distributions of each identified model. Twenty-seven (28) different models emerged as the total of the different models possible.
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Pressure Derivative Behavior of Two-Layered Reservoir with Vertical Wells
Advanced Materials Research, 2009Co-Authors: D. Akhipemelo, E. Steve AdewoleAbstract:Layered Reservoir systems present a huge challenge to both Reservoir and production engineers, because of difficulty encountered in Reservoir management and well completions. In this paper, the solution to a 2D Reservoir model is utilized to study pressure and pressure derivatives of a two-Layered crossflow Reservoir with a vertical well. No skin and wellbore effects are included. The interlayer fluid transmissibility ratio is varied for the same layers properties, to study the effects of layers heterogeneity and well completion choice on flow performance. Results show that decreasing values of specific transmissibility ratio, , signifies completion in the more permeable layer, a shift in the pressure response to the left and a short transition period to depletion of the second layer. Furthermore, increasing values means that the well is completed in the lower permeability layer causing delay in the depletion of the second layer as a result of long transition period.