Predicting Productivity Index of Horizontal Wells

2006 ◽  
Vol 129 (2) ◽  
pp. 89-95 ◽  
Author(s):  
Shaojun Wang ◽  
Joe Eaton
Keyword(s):  
Flow Resistance ◽  
Horizontal Well ◽  
Extreme Case ◽  
Horizontal Wells ◽  
Productivity Index ◽  
Horizontal Flow ◽  
Vertical Flow ◽  
Vertical Permeability ◽  
Horizontal Wellbore ◽  
New Equation

The popular Joshi model slightly overestimated the flow resistance of a horizontal well. As a result of this, the Joshi model underpredicts the productivity index (PI) of a horizontal well by a few percent. In the extreme case in which vertical permeability goes to zero, the Joshi model predicts a 0.0 stb∕day-psi PI, which is wrong. In this paper, the flow for a horizontal well is divided into three flows: the flow in the reservoir above the horizontal wellbore, the flow in the reservoir with a thickness of 2rw containing the horizontal wellbore, and a flow in the reservoir below the horizontal well bore. The second flow is assumed to be pure horizontal flow. The first and third flows can be further divided into a horizontal flow and a vertical flow. In this paper, the equation for each flow is provided, and then combining these flows we give the equation to calculate the effective PI of horizontal wells. In addition, when the horizontal wellbore is not located at the h∕2 midpoint of a reservoir, the Joshi model predicts an increasing PI, which is intuitively and mathematically an incorrect trend. This paper derives a new equation to compute the PI of horizontal wells when the wellbore is eccentric relative to the reservoir midpoint. The new equation generates the correct trend.

scholarly journals Pressure behaviour of a horizontal well sandwiched between two parallel sealing faults

2020 ◽  
Vol 39 (1) ◽  
pp. 148-153
Author(s):  
A.V. Ogbamikhumi ◽  
E.S. Adewole
Keyword(s):  
Horizontal Well ◽  
Source Function ◽  
Solution Method ◽  
Productivity Index ◽  
Production Potential ◽  
Dimensionless Length ◽  
Vertical Permeability ◽  
Dimensionless Pressure ◽  
Reservoir Geometry ◽  
Diffusivity Equation

Generally, reservoir fluid flow is governed by diffusivity equation and solution to this equation helps to investigate pressure behaviour under certain reservoir and wellbore boundary conditions. In this paper however, the analytical solution method of Green and Source function is deployed to determine the performance of a horizontal well located between two parallel sealing faults, assuming simple rectangular reservoir geometry. Also, the dimensionless pressure and derivative approach is applied for all computations as it prevents the problem of unit conversions, reduces longer expressions and it helps to handle numerical values. The pressure expression derived from this work reveals that a maximum of two flow periods occur for the stated reservoir model. It was found out that an inverse relationship exists between dimensionless pressure and dimensionless length while pressure increased with thickness. Also high vertical permeability shortens the effect of the early radial flow period experienced by the horizontal well, thereby increasing productivity index. Finally, it was discovered that increased perforation length reduces the production potential of the horizontal well. Keywords: Dimensionless pressure, pressure derivatives, heterogeneity, pressure performance, reservoir and wellbore characterization.

A Semianalytical Model for Horizontal-Well Productivity With Pressure Drop Along the Wellbore

SPE Journal ◽  
2018 ◽  
Vol 23 (05) ◽  
pp. 1603-1614 ◽  
Author(s):  
Wanjing Luo ◽  
Changfu Tang ◽  
Yin Feng
Keyword(s):  
Reynolds Number ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Productivity Index ◽  
Type Curves ◽  
Penetration Ratio ◽  
New Type ◽  
The One

Summary This study aims to develop a semianalytical model to calculate the productivity index (PI) of a horizontal well with pressure drop along the wellbore. It has been indicated that by introducing novel definitions of horizontal-well permeability and conductivity, the equation of fluid flow along a horizontal well with pressure drop has the same form as the one for fluid flow in a varying-conductivity fracture. Thus, the varying-conductivity-fracture model and PI model can be used to obtain the PI of a horizontal well. Results indicate that the PI of a horizontal well depends on the interaction between horizontal-well conductivity, penetration ratio, and Reynolds number. New type curves of the penetration ratios with various combinations of parameters have been presented. A complete-penetration zone and a partial-penetration zone can be identified on the type curves. Based on the type curves, two examples have also been presented to illustrate the advantages of this work in optimizing parameters of horizontal wells.

Formation of a Methodology for Calculating the Optimal Number of Wells in the Development of Lenticular Formations to Achieve Maximum NPV

2021 ◽  
Author(s):  
Vadim Andreevich Rubailo ◽  
Kirill Dmitrievich Isakov ◽  
Alexey Stanislavovich Osipenko ◽  
Marcel Mansurovich Akhmadiev
Keyword(s):  
Horizontal Well ◽  
Horizontal Wells ◽  
Optimal Number ◽  
Project Development ◽  
Analytical Methodology ◽  
Petrophysical Parameters ◽  
Early Stages ◽  
Reservoir Fluid ◽  
Economic Parameters ◽  
New Equation

Abstract The work is devoted to the analytical methodology for the development of oil lenticular formations. The method is based on the theory of potentials for vertical and horizontal wells. The work takes into account the interference of wells, geological and petrophysical parameters of lenses, as well as the properties of the reservoir fluid, and a new equation for estimating the inflow to a horizontal well is derived. An assessment of the correctness of this work on the company's assets was made. The dependence for the express estimation of the number of wells depending on the economic parameters at the early stages of project development is obtained.

Estimating the Specific Productivity Index in Horizontal Wells From Distributed-Pressure Measurements Using an Adjoint-Based Minimization Algorithm

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 742-751 ◽  
Author(s):  
F.. Farshbaf Zinati ◽  
J.D.. D. Jansen ◽  
S.M.. M. Luthi
Keyword(s):  
Horizontal Well ◽  
Adjoint Method ◽  
Horizontal Wells ◽  
Measurement Noise ◽  
Productivity Index ◽  
Specific Productivity ◽  
Inversion Method ◽  
Pressure Measurements ◽  
Sensor Resolution ◽  
Distributed Pressure

Summary Recent developments in the deployment of distributed-pressure-measurement devices in horizontal wells promise to lead to a new, low-cost, and reliable method of monitoring production and reservoir performance. Practical applicability of distributed-pressure sensing for quantitative-inflow detection will strongly depend on the specifications of the sensors, details of which were not publicly available at the time of publication. Therefore, we theoretically examined the possibility of identifying reservoir inflow from distributed-pressure measurements in the well. The wellbore and nearwellbore region were described by semianalytical steady-state models, and a gradient-based inversion method was applied to estimate the specific productivity index (SPI) as a function of along-well position. We employed the adjoint method to obtain the gradients, which resulted in a computationally efficient inversion scheme. With the aid of two numerical experiments (one of which was based on a real well and reservoir), we investigated the effects of well and reservoir parameters, sensor spacing, sensor resolution, and measurement noise on the quality of the inversion results. In both experiments, we generated synthetic measurements with the aid of a high-resolution reservoir-simulation model and used these to test the semianalytical inversion algorithm. In the first experiment, we considered a 2000-m horizontal well passing through two 300-m high-permeability streaks in a background with a permeability that was 10 times lower. The location of the streaks and the SPIs along the well were detected with fair accuracy using 20 unknown parameters (SPI values) and 20 pressure measurements. Decreasing the number of measurements resulted in a poorer detection of the streaks and their SPIs. The detection performance also decreased for increasing noise levels and deteriorated sensor resolution, though the negative effect of random measurement noise was cancelled out primarily by stacking multiple measurements. The detrimental effects of measurement noise and low sensor resolution were strongest in areas where the inflow was lowest (usually close to the toe). The second experiment concerned a high-rate near-horizontal well with slightly varying inclination that intersected a dipping package of formations with strongly variable permeabilities. Additionally, a satisfactory detection of SPIs was obtained even though the heterogeneities were no longer perpendicular to the well as in the first experiment. As a result of using the simple semianalytical forward model and the adjoint method, the inversions typically required less than 90 seconds on a standard laptop. This offered the opportunity to extend the algorithm to multiphase flow and dynamic applications (pressure-transient testing), while still maintaining sufficient computational speed to perform the inversion in real time.

scholarly journals Productivity Evaluation for Long Horizontal Well Test in Deep-Water Faulted Sandstone Reservoir

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zhiwang Yuan ◽  
Li Yang ◽  
Yingchun Zhang ◽  
Rui Duan ◽  
Xu Zhang ◽  
...  
Keyword(s):  
Steady State ◽  
Deep Water ◽  
Horizontal Well ◽  
Evaluation Method ◽  
Horizontal Wells ◽  
Productivity Index ◽  
Test Time ◽  
Well Test ◽  
Well Productivity ◽  
Sandstone Reservoir

For deep-water faulted sandstone reservoirs, the general practice is to design long horizontal wells improving well productivity. During the project implementation stage, well tests are performed on all drilled wells to evaluate well productivity accurately. Furthermore, multisize chokes are often utilized in a shorten test time for loosen formation, high test cost, and high well productivity. Nevertheless, the conventional productivity evaluation approach cannot accurately evaluate the well test productivity and has difficulty in determining the underneath pattern. As a result, the objective of this paper is to determine a productivity evaluation method for multisize chokes long horizontal well test in deep-water faulted sandstone reservoir. This approach introduces a productivity model for long horizontal wells in faulted sandstone reservoir. It also includes the determination of steady-state test time and the productivity evaluation method for multisize chokes. In this paper, the EGINA Oilfield, a deep-water faulted sandstone reservoir, located in West Africa was chosen as the research target. Based on Renard and Dupuy’s steady-state equation, the relationship between the productivity index per meter and the length of horizontal section was derived. Consequently, this relationship is used to determine the productivity pattern for long horizontal wells with the same geological features, which can provide more accurate productivity evaluations for tested wells and forecast the well productivity for untested wells. After implementing this approach on the EGINA Oilfield, the determined relationship is capable to accurately evaluate the test productivity for long horizontal wells in reservoirs with similar characteristics and assist in examination and treatment for horizontal wells with abnormal productivity.

Design of Horizontal Wellbore in Dadas Shales of Turkey by Considering Wellbore Stability and Reservoir Geomechanics

2021 ◽  
Author(s):  
Sukru Merey ◽  
Can Polat ◽  
Tuna Eren
Keyword(s):  
Hydraulic Fracturing ◽  
Horizontal Well ◽  
Oil And Gas ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Wellbore Stability ◽  
Horizontal Drilling ◽  
Horizontal Wellbore ◽  
Reservoir Geomechanics ◽  
Maximum Horizontal Stress

Abstract Currently, many horizontal wells are being drilled in Dadas shales of Turkey. Dadas shales have both oil (mostly) and gas potentials. Thus, hydraulic fracturing operations are being held to mobilize hydrocarbons. Up to 1000 m length horizontal wells are drilled for this purpose. However, there is not any study analyzing wellbore stability and reservoir geomechanics in the conditions of Dadas shales. In this study, the directions of horizontal wells, wellbore stability and reservoir geomechanics of Dadas shales were designed by using well log data. In this study, the python code developed by using Kirsch equations was developed. With this python code, it is possible to estimate unconfined compressive strength in along wellbore at different deviations. By analyzing caliper log, density and porosity logs of Dadas shales, vertical stress of Dadas shales was estimated and stress polygon for these shale was prepared in this study. Then, optimum direction of horizontal well was suggested to avoid any wellbore stability problems. According to the results of this study, high stresses are seen in horizontal directions. In this study, it was found that the maximum horizontal stress in almost the direction of North-South. The results of this study revealed that direction of maximum horizontal stress and horizontal well direction fluid affect the wellbore stability significantly. Thus, in this study, better horizontal well design was made for Dadas shales. Currently, Dadas shales are popular in Turkey because of its oil and gas potential so horizontal drilling and hydraulic fracturing operations are being held. However, in literature, there is no study about horizontal wellbore designs for Dadas shales. This study will be novel and provide information about the horizontal drilling design of Dadas shales.

scholarly journals Study of the horizontal sidetracking efficiency using hydrodynamic modeling (on the example of a Kazakhstani field)

2022 ◽  
Vol 320 (1) ◽  
pp. 42-50
Author(s):  
K.A. Soltanbekova ◽  
◽  
B.K. Assilbekov ◽  
A.B. Zolotukhin ◽  
◽  
...  
Keyword(s):  
Horizontal Well ◽  
Horizontal Wells ◽  
Vertical Wells ◽  
Optimal Length ◽  
Pressure Losses ◽  
Rate Versus ◽  
Horizontal Wellbore ◽  
Effective Development ◽  
Complex Architecture ◽  
Economic Criteria

One of the modern approaches for the effective development of small deposits is the construction and operation of wells with a complex architecture: horizontal wells (HW), sidetracks (BS, BGS), multilateral wells (MLW). Sidetracking makes it possible to reanimate an old well that is in an emergency state or inactivity for technological reasons, by opening layers that have not been previously developed, bypassing contamination zones, or watering the formation. This study examines the possibility of using horizontal sidetracks in the operating wells of the field of the Zhetybai group. To select the optimal length of the horizontal sidetrack of the wells, graphs of the dependences of the change in flow rate versus length of the horizontal well were built, taking into account the pressure losses due to friction. It can be seen from the dependence of NPV versus length of the horizontal wellbore that the maximum NPV is achieved with a horizontal wellbore length of 100 m. A further increase in the length of the horizontal wellbore leads to a decrease in NPV. This is due, firstly, to a decrease in oil prices, and secondly, interference of wells, a small number of residual reserves, and a small oil-bearing area. As a result of a comparison of technical and economic criteria, the optimal length of a horizontal wellbore is from 100-300 meters. Comparison of the flow rates of vertical wells and wells with horizontal sidetracks showed a clear advantage over the latter in all respects.

The Effect of Skins at a Natural Fracture Crossed Normally by a Finite Horizontal Well

SPE Journal ◽  
2013 ◽  
Vol 18 (02) ◽  
pp. 233-242
Author(s):  
Michael Prats ◽  
R.. Raghavan
Keyword(s):  
Flow Resistance ◽  
Horizontal Well ◽  
Natural Fracture ◽  
Productivity Index ◽  
Pressure Gradients ◽  
Fracture Permeability ◽  
Positive Skin ◽  
Linear Flow ◽  
Matrix Production ◽  
Small Improvement

Summary The effect of zones of impaired permeability at the faces of natural fractures on the performance of a finite-length well, completed normal to the fracture in an infinite 3D system, is analyzed by use of known analytical procedures capable of considering large ratios of fracture permeability to matrix. The zones of impaired permeability, called fracture skins, are represented as planes of equivalent flow resistance. The most important findings of this scoping study on the influence of natural fracture skins on reservoir behavior are that they have much less effect on the productivity index (PI) of a horizontal well than a skin on a well, which is considered to be because of the large differences in the skin areas through which the flows occur, as well as the adverse effect of radial compared with linear flow and the fact that matrix production from the well is not affected by the fracture skin; they lead to a small improvement in the steady-state PI of a well, which is counterintuitive (on the basis of the experience of positive skin on a well always reducing its PI); and they affect how the flux entering the fracture is distributed with distance from the well: the larger the skin, the more dispersed the flux. It is surmised the improvement in PI is associated with the reduction in local reservoir pressure gradients accompanying the reduced fluxes entering the fracture near the well. Unequal fracture skins, even with the fracture at the midpoint of the finite well, result in crossflow across the fracture over significant distances from the well.

SUCCESSFUL APPLICATION AND LIMITATIONS OF HORIZONTAL WELLS

2021 ◽  
Vol 5 (12(81)) ◽  
pp. 4-8
Author(s):  
S. Abbasova
Keyword(s):  
Oil Recovery ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Field Application ◽  
Vertical Wells ◽  
Flow Rates ◽  
Reservoir Conditions ◽  
Horizontal Wellbore ◽  
The Impact ◽  
Working Agent

In fields with low-permeable reservoirs, the use of vertical wells becomes economically unprofitable, since a significant amount of reserves remains not involved in development. In these conditions, the most rational use of horizontal wells becomes. A horizontal well is drilled parallel to the plane of the reservoir and can drain a larger area than a vertical one, which makes it possible to increase the impact of the working agent. This, in turn, leads to an increase in well productivity and, ultimately, to an increase in oil recovery of productive formations. Due to the horizontal wellbore, fractured areas are exposed, due to which the flow rates of these wells increase somewhat compared to vertical ones. It becomes possible to develop a reservoir with minimal drawdowns with a much smaller number of wells. The purpose of this article is to provide a brief overview of the field application of horizontal wells in various reservoir conditions. The review of economically successful and unsuccessful wells allows the creation of a certain kind of list of parameters that are of the greatest importance for consideration in order to select a commercially successful application of horizontal wells.

A Holistic Study on Performance Evaluation of Horizontal Wells and its Implications on Tight Spacing Drilling Strategy in Mauddud Reservoir

2021 ◽  
Author(s):  
Lakshi Konwar ◽  
Bader Alhammadi ◽  
Ebrahim Alawainati ◽  
Ajithkumar Panicker
Keyword(s):  
Performance Evaluation ◽  
Future Development ◽  
Horizontal Well ◽  
Horizontal Wells ◽  
Productivity Index ◽  
Water Production ◽  
Vertical Wells ◽  
Productivity Improvement ◽  
Well Productivity ◽  
Improvement Factor

Abstract The objective of this paper is to present the comparative results of comprehensive analysis of horizontal well productivity and completion performance with vertical wells drilled and completed within same time window in the Mauddud reservoir in the Bahrain Oil Field. The study also focuses on performance evaluation of horizontal wells drilled in different areas of the field. Key reservoir risks and uncertainties associated with horizontal wells are identified, and contingency and mitigation plans are devised to address them. Besides controlling gas production, the benefits of using cemented horizontal wells over vertical wells are highlighted based on performance of recently completed workovers and economic evaluation. Reservoir and well performance are analyzed using a variety of analytical techniques such as well productivity index (PI), productivity improvement factor (PIF), normalized productivity improvement factor (PIFn), well productivity coefficient (Cwp), in conjunction with a statistical distribution function to reflect the average and most likely values. In addition, average oil/gas/water production, cumulative production, reserves, and estimated ultimate recovery (EUR) are compared for both vertical and horizontal wells using decline curve analysis. Furthermore, economics are evaluated for tight spacing drilling with vertical wells, as well as horizontal cemented wells, to optimize future development of Mauddud reservoir. Based on the evaluation, it is inferred that the average horizontal well outperforms a vertical well in terms of production rate, PI, PIF, reserves, and EUR in the field except in waterflood areas. Based on average cumulative oil, reserves and EUR, and well productivity coefficient, overall performance of horizontal wells are better in the GI area in comparison their counterparts in the North/South areas of the Mauddud reservoir, where the dominant mechanism is strong water drive. High gas and water production in horizontal wells are attributed to open-hole completions of the wells and the possibility of poor cementing. A trial has been completed recently in a few horizontal wells using cased-hole cemented completion with selected perforations, resulting in improved oil rates and the drastic reduction of gas to oil ratio. Furthermore, two new cased-hole cemented horizontal wells are planned in 2021 as a trial. A detailed cost-benefit analysis using a net present value concept is performed, leading to a rethink of future development strategies with a mix of both vertical as well as horizontal wells in the GI area. Using the dimensionless correlations and distribution functions, the productivity and PIF of new horizontal wells to be drilled in any area can be predicted during early prognosis given the values of average reservoir permeability, well length, and fluid properties. This study can be used as a benchmark for the development of a thin oil column with a large and expanding gas cap under crestal gas injection using both vertical and horizontal wells.

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