scholarly journals Investigation on Interference Test for Wells Connected by a Large Fracture

2019 ◽  
Vol 9 (1) ◽  
pp. 206
Author(s):  
Guofeng Han ◽  
Yuewu Liu ◽  
Wenchao Liu ◽  
Dapeng Gao
Keyword(s):  
Double Porosity ◽  
Flow In Porous Media ◽  
Connection Form ◽  
Analysis Model ◽  
Pressure Derivative ◽  
Type Curve ◽  
Type Curves ◽  
Multi Stage ◽  
Interference Test ◽  
Straight Lines

Pressure communication between adjacent wells is frequently encountered in multi-stage hydraulic fractured shale gas reservoirs. An interference test is one of the most popular methods for testing the connectivity of a reservoir. Currently, there is no practical analysis model of an interference test for wells connected by large fractures. A one-dimensional equation of flow in porous media is established, and an analytical solution under the constant production rate is obtained using a similarity transformation. Based on this solution, the extremum equation of the interference test for wells connected by a large fracture is derived. The type-curve of pressure and the pressure derivative of an interference test of wells connected by a large fracture are plotted, and verified against interference test data. The extremum equation of wells connected by a large fracture differs from that for homogeneous reservoirs by a factor 2. Considering the difference of the flowing distance, it can be concluded that the pressure conductivity coefficient computed by the extremum equation of homogeneous reservoirs is accurate in the order of magnitude. On the double logarithmic type-curve, as time increases, the curves of pressure and the pressure derivative tend to be parallel straight lines with a slope of 0.5. When the crossflow of the reservoir matrix to the large fracture cannot be ignored, the slope of the parallel straight lines is 0.25. They are different from the type-curves of homogeneous and double porosity reservoirs. Therefore, the pressure derivative curve is proposed to diagnose the connection form of wells.

Pressure Transient Behavior for Alternating Polymer Flooding in a Three-zone Composite Reservoir

2017 ◽  
Vol 25 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Changyu Zhu ◽  
Shiqing Cheng ◽  
Youwei He ◽  
Engao Tang ◽  
Xiaodong Kang ◽  
...  
Keyword(s):  
History Matching ◽  
Petroleum Industry ◽  
Composite Model ◽  
Polymer Flooding ◽  
Analysis Model ◽  
High Concentration ◽  
Pressure Derivative ◽  
Type Curves ◽  
Formation Evaluation ◽  
Pressure Analysis

Alternating polymer flooding has achieved great attractions recently in oil industry, however, the research of pressure analysis in alternating polymer flooding reservoir is rare. This work presents a numerical pressure analysis method of three-zone composite model for formation evaluation. A new numerical pressure analysis model (three-zone composite model) is established by considering diffusion, convection, shear, and inaccessible pore volume, which is based on the rheology experiments. Based on this model, the type curves are then developed and sensitivity analysis is further conducted. The type curves have seven regimes in three-zone composite model. The characteristic is the obvious upturn of pressure derivative curve in transient regime between low concentration and high concentration polymer solution. Formation parameters can be interpreted by history matching and formation evaluation can be conducted based on this model. As an important part of formation evaluation, formation damage as a result of adsorption of polymers in porous media is evaluated by comparing the interpreted permeability with the original value before polymer flooding. The field test data proves that this proposed method can accurately evaluate reservoir characteristics in alternating polymer flooding reservoirs, which emphasizes the potential application of this method in petroleum industry.

scholarly journals Solution and type curves for the seepage model of the water-bearing coalbed with leakage recharge

2017 ◽  
Vol 21 (1) ◽  
pp. 17 ◽  
Author(s):  
Wangang Chen ◽  
Yu Yang ◽  
Hansen Sun ◽  
Chengwei Zhang ◽  
Qin Wen ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Radial Flow ◽  
Curve Matching ◽  
Pressure Derivative ◽  
Type Curve ◽  
Type Curves ◽  
Reservoir Permeability ◽  
Leakage Coefficient ◽  
Seepage Theory ◽  
Seepage Model

To analyze the effects of the leakage recharge of the aquifer on the initial dewatering of coalbed methane wells, the mathematical seepage model of water in the coalbed considering the aquifer leakage was established by using the leakage coefficient according to the unsteady seepage theory. The model was solved after Laplace transform and the Stehfest numerical reverse inversion was used to obtain the solution in right space. Then, the log-log type curves of pressure and pressure derivative were created with new combinations of parameters. Based on the natural seepage mechanism, the influence of aquifer leakage on curve shape was judged. It is found that the radial flow ends earlier as the leakage coefficient increases. Moreover, it was proposed to obtain reservoir permeability, skin factor, and leakage coefficient by using type curve matching. The type curves are useful for quantitatively evaluating the level of leakage, thereby guiding the adjustment of the following production system for CBM wells. Curvas de solución y tipo para el modelo de filtración de capas carboníferas acuíferas con recarga de fugasResumenEste estudio estableció el modelo matemático de filtración de agua en una capa carbonífera al estimar la salida acuífera con el uso del coeficiente de fuga, de acuerdo con la teoría de filtración inestable, para analizar los efectos en la recarga de pérdida de fluidos de un acuífero en el drenado inicial para pozos de gas metano.  El modelo se resolvió tras usar la transformación Laplace y la inversión numérica Stehfest para encontrar la respuesta en el lugar indicado. Luego, se creó la representación algorítmica de la presión y la presión derivativa con nuevas combinaciones de parámetros. Se evaluó la influencia de la pérdida de fluido del acuífero en la forma de la curva con base al mecanismo físico de filtración. Se estableció que el flujo radial finaliza antes de que el coeficiente de pérdida de fluido se incremente. Además, se propone el uso de la curva tipo correspondiente para obtener la permeabilidad del reservorio, el factor de daño y el coeficiente de pérdida de fluido. Las curvas tipo son útiles para evaluar cuantitativamente el nivel de la pérdida de fluido, y de esta manera guiar el ajuste de un sistema de producción consecuente para pozos de gas metano de carbón.

Analytical Model for Vertical Interference Tests Across Low-Permeability Zones

1985 ◽  
Vol 25 (03) ◽  
pp. 407-418 ◽  
Author(s):  
R.E. Bremer ◽  
Winston Hubert ◽  
Vela Saul
Keyword(s):  
Point Source ◽  
Test Data ◽  
Low Permeability ◽  
Test Analysis ◽  
Type Curve ◽  
Type Curves ◽  
Pulse Test ◽  
Vertical Permeability ◽  
Interference Test ◽  
Interference Tests

Abstract A mathematical model is developed that describes fluid flow and pressure behavior in a reservoir consisting of two permeable zones separated by a zone of low permeability, Or a "tight zone." This model can be used to design and to interpret buildup, vertical, interference, and pulse tests conducted in a single well or multiple wells across lithological strata. Dimensionless pressure functions and corresponding parametric type curves are derived to interpret vertical interference test data for tight-zone vertical penneability. Application of these type curves is illustrated using field data from two vertical interference tests. Test results obtained with the tight-zone model are shown to compare favorably with results obtained by usingcomputer simulations andBurns' method based on the uniform anisotropy assumption. Computer simulation using a numerical model also shows that high near-wellbore conductivity from a packer leak or poor cement job could not have adversely affected test results. The model presented and the type-curve interpretation method outlined are accurate for designing and interpreting single-well vertical interference tests across low-permeability zones. Introduction The knowledge of vertical flow properties across a low-permeability stratum is becoming increasingly important in reservoir development, especially when enhanced recovery projects are proposed for stratified reservoirs. Vertical well testing is a technique commonly used to determine values for the in-situ vertical permeability of a formation. Either the vertical interference or vertical pulse test may be used, depending on the amount of time required to obtain the necessary pressure response. The method of vertical interterence testing first was introduced by Burns,1 and later developed by Prats.2 Burns' model is based on the assumption of a homogeneous, infinite-acting reservoir with an average vertical permeability smaller than horizontal permeability. Four geometric parameters are used to computer-generate a type curve for analyzing the test data. One difficulty is that each type curve generated is specific to the four geometric parameters and, hence, to the well completion used. The analysis method proposed by Prats uses a plotting technique that does not require computer solutions. However, his technique is restricted by a point-source assumption; that is, the perforated production and observation intervals must be short compared with the distance between them. The most widely used vertical pulse test analysis technique was developed by Falade and Brigham.3–5 Briefly, the method uses sets of correlation curves relating a dimensionless pulse length and dimensionless pulse amplitude. Corrections can be made to account for the upper and lower formation boundaries. It should be noted that the times as given in the Falade and Brigham technique4,5 are too low by a factor of four.6 A second vertical pulse test analysis method, published by Hirasaki,7 is less general in that it considers only the situation with perforations at the upper and lower boundaries. Both methods use a point-source assumption. All previous vertical interference1,2 and vertical pulse3,4,7 test interpretation techniques were developed to determine vertical permeability in a homogeneous single-layer reservoir. These methods may be applied to stratified reservoirs where permeability contrasts are known to occur; however, they may yield misleading results in these cases where the homogeneous reservoir assumption is not justified. This paper presents an analytical model and interpretation technique to analyze vertical interference test data for tight-zone vertical permeability in a reservoir consisting of two permeable zones separated by a tight zone or a zone of low permeability. Pressure response data in the observation zone are plotted in a ?p vs. ?t format on log-log coordinates and matched against one of two type curves. The result of this match is a value for horizontal permeability in the upper and lower layers and a value for the effective vertical permeability across the tight zone. The type curves included are applicable for a wide range of thickness ratios between the permeable and low-permeability layers. Additionally, use of the model is not restricted by a point-source assumption.

Mahakam Field Characterization Using Production Type-Curve With Business Intelligence Application

2020 ◽  
Author(s):  
P. Noverri
Keyword(s):  
Business Intelligence ◽  
Data Gathering ◽  
Production Data ◽  
Type Curve ◽  
Type Curves ◽  
Production Type ◽  
Efficient Data ◽  
Production Behavior ◽  
Factor Type ◽  
Mahakam Delta

Delta Mahakam is a giant hydrocarbon block which is comprised two oil fields and five gas fields. The giant block has been considered mature after production for more than 40 years. More than 2,000 wells have been drilled to optimize hydrocarbon recovery. From those wells, a huge amount of production data is available and documented in a well-structured manner. Gaining insight from this data is highly beneficial to understand fields behavior and their characteristics. The fields production characterization is analyzed with Production Type-Curve method. In this case, type curves were generated from production data ratio such as CGR, WGR and GOR to field recovery factor. Type curve is considered as a simple approach to find patterns and capture a helicopter view from a huge volume of production data. Utilization of business intelligence enables efficient data gathering from different data sources, data preparation and data visualization through dashboards. Each dashboard provides a different perspective which consists of field view, zone view, sector view and POD view. Dashboards allow users to perform comprehensive analysis in describing production behavior. Production type-curve analysis through dashboards show that fields in the Mahakam Delta can be grouped based on their production behavior and effectively provide global field understanding Discovery of production key information from proposed methods can be used as reference for prospective and existing fields development in the Mahakam Delta. This paper demonstrates an example of production type-curve as a simple yet efficient method in characterizing field production behaviors which is realized by a Business Intelligent application

Effect of Non-Darcy Flow on the Constant-Pressure Production of Fractured Wells

1981 ◽  
Vol 21 (03) ◽  
pp. 390-400 ◽  
Author(s):  
K.H. Guppy ◽  
Heber Cinco-Ley ◽  
Henry J. Ramey
Keyword(s):  
Constant Pressure ◽  
Darcy Flow ◽  
Flow In Porous Media ◽  
Graphical Form ◽  
Finite Conductivity ◽  
Fracture Conductivity ◽  
Type Curves ◽  
Pressure Behavior ◽  
Apparent Conductivity ◽  
Constant Rate

Abstract In many low-permeability gas reservoirs, producing a well at constant rate is very difficult or, in many cases, impossible. Constant-pressure production is much easier to attain and more realistic in practice. This is seen when production occurs into a constant-pressure separator or during the reservoir depletion phase, when the rate-decline period occurs. Geothermal reservoirs, which produce fluids that drive backpressure turbines, and open-well production both incorporate the constant-pressure behavior. For finite-conductivity vertically fractured systems, solutions for the constant-pressure case have been presented in the literature. In many high-flow-rate wells, however, these solutions may not be useful since high velocities are attained in the fracture, which results in non-Darcy effects within the fracture. In this study, the effects of non-Darcy flow within the fracture are investigated. Unlike the constant-rate case, it was found that the fracture conductivity does not have a constant apparent conductivity but rather an apparent conductivity that varies with time. Semianalytical solutions as well as graphical solutions in the form of type curves are presented to illustrate this effect. An example is presented for analyzing rate data by using both solutions for Darcy and non-Darcy flow within the fracture. This example relies on good reservoir permeability from prefracture data to predict the non-Darcy effect accurately. Introduction To fully analyze the effects of constant-bottomhole-pressure production of hydraulically fractured wells, it is necessary that we understand the pressure behavior of finite-conductivity fracture systems producing at constant rate as well as the effects of non-Darcy flow on gas flow in porous media. Probably one of the most significant contributions in the transient pressure analysis theory for fractured wells was made by Gringarten et al.1,2 In the 1974 paper,2 general solutions were made for infinite-conductivity fractures. Cinco et al.3 found a more general solution for the case of finite-conductivity fractures and further extended this analysis in 1978 to present a graphical technique to estimate fracture conductivity.4 For the case of constant pressure at the wellbore, solutions were presented in graphical form by Agarwal et al.5 In his paper, a graph of log (1/qD) vs. log (tDxf) can be used to determine the conductivity of the fracture by using type-curve matching. Although such a contribution is of great interest, unique solutions are difficult to obtain. More recently, Guppy et al.6 showed that the Agarwal et al. solutions may be in error and presented new type curves for the solution to the constant-pressure case assuming Darcy flow in the fracture. That paper developed analytical solutions which can be applied directly to field data so as to calculate the fracture permeability-width (kfbf) product.

Guest Editorial: Spacing Ourselves to Death

2021 ◽  
Vol 73 (09) ◽  
pp. 8-10
Author(s):  
Justin Hayes
Keyword(s):  
Oil And Gas ◽  
Cash Flows ◽  
Simple Type ◽  
Financial Model ◽  
Type Curve ◽  
Type Curves ◽  
Technical Staff ◽  
Future Performance ◽  
Well Spacing ◽  
Proper Name

If you talk to a typical subsurface professional working on unconventionals today (e.g., a reservoir engineer, completion engineer, geologist, petrophysicist, etc.) as I have in person and through media such as LinkedIn, you will find that many lament one key thing: Our sophisticated models have been reduced too much. Of course, I am generalizing and those are not the words they use; the lamentations come in many forms. The dissatisfaction with oversimplification is most easily observed as dis-taste for the type curve, the simplified model we use to predict upcoming new drills. (Yes, I know many of you will want to refer to them by their “proper” name: type well curve; I will be sticking with the colloquial version.) A simple meme posted on LinkedIn about type curves garnered one of the most engaged conversations I have seen amongst technical staff. The responses varied from something like “Thank God someone finally said this out loud” to comments such as “I don’t know anything better than type curves.” Most comments were closer to the former than the latter. What is even more remarkable is that our investors feel the same. In personal conversations, many of them refer to our type curves simply as “lies.” This perception, coupled with the historical lack of corporate returns, led investors away from our industry in droves. Many within the industry see it differently and want to blame the exodus on other factors such as oil and gas prices, climate change, competition from renewables, other environmental, social, and governance (ESG) issues, the pandemic, or OPEC’s unwillingness to “hold the bag” any longer. If you ask them, though, investors will tell you a simple answer: The unconventional business destroyed way too much capital and lied too much through the type curves. Why is it that both investors and technical staff are unhappy with our ability to accurately model future performance? Why can’t we deliver returns? The typical unconventional-focused oil and gas company has two models that are critical to the business. First is the subsurface model, with which we are all intimately familiar in its various forms, and the second is the corporate financial model, which is focused on cash flows, income, and assets/liabilities. It is unfortunate that the two models are separate. It means we must simplify one or both so they can communicate with each other. How can you observe this oversimplification while it is happening? It is happening when the finance staff say, “Please just give me a simple type curve and well count; I need to model, optimize, and account for debt/leverage, equity, and cash flows.” Meanwhile, the technical staff say, “Please just give me a CAPEX budget or a well count; I need to model, optimize, and account for well spacing, completion design, land constraints, and operational constraints.” Looking back, we know that the winner in this tug-of-war of competing needs was the type curve.

Fully Coupled Finite Element Analysis of an Automatic Multi-Stage Cold Forging Process

2020 ◽  
Vol 311 ◽  
pp. 88-93
Author(s):  
Jong Bok Byun ◽  
Hyun Joon Lee ◽  
Jong Bok Park ◽  
Il Dong Seo ◽  
Man Soo Joun
Keyword(s):  
High Strength ◽  
Material Model ◽  
Die Design ◽  
Cold Forging ◽  
Complete Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
Forging Process ◽  
Multi Stage ◽  
Analysis Scheme

In this paper, non-isothermal analysis of an automatic multi-stage cold forging process of a ball-stud is conducted using a new material model which is a closed form function of strain, temperature and strain rate covering low and warm temperatures for high-strength stainless steel SUS304. An assembled die structural analysis scheme is employed for revealing the detailed die stresses, which is of great importance for process and die design for metal forming of the materials with high strengths. Die elastic deformation is dealt with to predict final geometries of material with higher accuracy. A complete analysis model is proposed to be used for optimal design of process and die designs in automatic multi-stage cold forging of high-strength materials.

scholarly journals A New DEA Model for Evaluation of Supply Chains: A Case of Selection and Evaluation of Environmental Efficiency of Suppliers

Symmetry ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 565 ◽  
Author(s):  
Krmac ◽  
Djordjević
Keyword(s):  
Sensitivity Analysis ◽  
Complex Problem ◽  
Environmental Efficiency ◽  
Data Envelopment Analysis Model ◽  
Data Envelopment ◽  
Analysis Model ◽  
Chain Management ◽  
Dea Model ◽  
Multi Stage ◽  
Stage System

Supply Chain Management (SCM) represents an example of a complex multi-stage system. The SCM involves and connects different activities, from customer’s orders to received services, all with the aim of satisfying customers. The evaluation of a particular SCM is a complex problem because of the internally linked hierarchical activities and multiple entities. In this paper, the introduction of a non-radial DEA (Data Envelopment Analysis) model for the evaluation of different components of SCM, primarily in terms of sustainability, is the main contribution. However, in order to confirm the novelty and benefits of this new model in the field of SCM, a literature review of past applications of DEA-based models and methods are also presented. The non-radial DEA model was applied for the selection and evaluation of the environmental efficiency of suppliers considering undesirable inputs and outputs resulting in a better ranking of suppliers. Via perturbation of the data used, behavior, as well as the benefits and weaknesses of the introduced model are presented through sensitivity analysis.

scholarly journals Multi-stage preconditioners for thermal–compositional–reactive flow in porous media

2020 ◽  
Vol 418 ◽  
pp. 109607
Author(s):  
Matthias A. Cremon ◽  
Nicola Castelletto ◽  
Joshua A. White
Keyword(s):  
Porous Media ◽  
Flow In Porous Media ◽  
Reactive Flow ◽  
Multi Stage
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