A Model of Oil-Water Coning for Two-Dimensional, Areal Reservoir Simulation

1976 ◽  
Vol 16 (02) ◽  
pp. 65-72 ◽  
Author(s):  
J.E. Chappelear ◽  
G.J. Hirasaki
Keyword(s):  
Finite Difference ◽  
Flow Resistance ◽  
Bottom Water ◽  
Effective Radius ◽  
Vertical Equilibrium ◽  
Well Model ◽  
Water Coning ◽  
Partial Completion ◽  
Oil Water ◽  
Reservoir Simulator

Abstract A model for oil-water coning in a partially perforated well has been developed and tested by perforated well has been developed and tested by comparison with numerical simulations. The effect of oil-water coning, including down-coning of oil, on field production is demonstrated by studying a small water drive reservoir whose complete production data arc known. production data arc known.The coning model is derived by assuming vertical equilibrium and segregated flow. A necessary correction for departure from vertical equilibrium in the immediate neighborhood of the well is developed The coning model is suitable for single-well studies or for inclusion in a reservoir simulator for two-dimensional, areal studies. Introduction The objective of this investigation of oil-water coning was to develop tools to evaluate operational problems for reservoirs with bottom water. Although problems for reservoirs with bottom water. Although any specific question can be answered (a least in principle) by finite-difference simulation, a practical principle) by finite-difference simulation, a practical problem occurs. Great detail may be necessary for problem occurs. Great detail may be necessary for a reservoir-wide simulation of problems involving coning. Two approaches are possible. One can use more accurate finite-difference equations (such as those derived by some type of Galerkin procedure) to solve the problem of insufficient accuracy. Or one can include in his simulator a "well model" that accurately predicts coning on the basis of near-well properties. The well model could be either another finite-difference subsystem or a formula theoretical or empirical (or both) in character. Our approach is to develop a theoretical model that can be installed in a finite-difference reservoir simulator. We feel that such a model, particularly if it is simple and widely applicable, has several advantages:(1)the assumptions made in the derivation aid in understanding coning;(2)the formula guides the engineer by indicating significant parameters and their relationships;(3)the existence parameters and their relationships;(3)the existence of a simple formula permits preliminary studies without a full simulation; and(4)the simple formula is easy to install in a reservoir simulator. This model for oil-water coning differs from others presented previously in two respects. First, presented previously in two respects. First, partial completion that does not necessarily extend partial completion that does not necessarily extend to the top of the formation is treated. Second, an effective radius that allows for vertical flow resistance is introduced. DESCRIPTION OF MODEL ASSUMPTIONS The geometric configuration for the coning model is a radially symmetric, homogeneous, anisotropic system with inflow at the outer boundary and with a partially perforated well. The fluid distribution is shown in Fig. 1. The presence of initial bottom water at 100-percent water saturation is considered. The perforated interval is assumed to be within the original oil column. The fluids are assumed to be incompressible. The model will be developed in steady-state flow. It is shown in Ref. 6 that the transient time for the start of flow is short for most practical problems and, thus, the rise of the cone can be represented as a succession of steady states. The fluids are assumed to flow in segregated regions, as shown in Fig. 1. The fractional flow into the perforated interval is assumed to be only a function of the fraction of the interval covered by each fluid and of the mobility ratio. The fluids are assumed to be in vertical equilibrium everywhere except near the wellbore. The departure from vertical equilibrium near the well caused by the vertical flow resistance is represented by an "effective radius." The expression for the effective radius represents the anisotropy through the vertical-to-horizontal permeability ratio. permeability ratio.The fluid flow equations are linearized by assuming that the average oil-column thickness over the drainage area can be used to compute the vertically averaged relative-permeability functions for the entire drainage area. SPEJ P. 65

scholarly journals FILTRATION MODEL OF OIL CONING IN A BOTTOM WATER-DRIVE RESERVOIR

2018 ◽  
Vol 15 (30) ◽  
pp. 725-733
Author(s):  
R. F. YAKUPOV ◽  
V. S. MUKHAMETSHIN ◽  
K. T. TYNCHEROV
Keyword(s):  
Hydrodynamic Model ◽  
Bottom Water ◽  
Water Contact ◽  
Hydrodynamic Simulation ◽  
Water Coning ◽  
Oil Water ◽  
Filtration Modeling ◽  
Water Saturated ◽  
Successive Method ◽  
Filtration Model

The purpose of the paper is the substantiation of the application of the oil coning technology in the process of the hydrodynamic simulation of the successive method, which includes the perforation of the casing below the level of oil-water contact; the drawing of water from the lower water-saturated part of the reservoir; the isolation of this perforation interval; the drilling-in of the near-caprock oil-saturated part of the reservoir and the production of near-caprock oil. The leading approach to the research of this problem is the method of filtration modeling of the oil and water coning processes in the reservoir. As a result of the study, a hydrodynamic model of a well has been created, which corresponds to the requirements of the visualization of the process, the authenticity and the possibility to control the necessary parameters of the model and to estimate the effectiveness of the technology.

Oil-Water Interface Measurements in Bottom Water Drive Pools

1967 ◽  
Vol 6 (02) ◽  
pp. 50-58
Author(s):  
W.J. Gray ◽  
G.J. Willmon
Keyword(s):  
Bottom Water ◽  
Water Interface ◽  
Oil Water

Use of Horizontal Drift-Flux Models For Simulating Wellbore Flow in SAGD Operations

2021 ◽  
Author(s):  
Mohammad Heidari ◽  
Christopher Istchenko ◽  
William Bailey ◽  
Terry Stone
Keyword(s):  
Flux Flow ◽  
Pressure Drops ◽  
Steam Assisted Gravity Drainage ◽  
Drift Flux ◽  
Pressure Profiles ◽  
Well Model ◽  
Inclination Angles ◽  
Operation Pressure ◽  
Reservoir Simulator ◽  
High Degree

Abstract The paper examines new horizontal drift-flux correlations for their ability to accurately model phase flow rates and pressure drops in horizontal and undulating wells that are part of a Steam-Assisted Gravity Drainage (SAGD) field operation. Pressure profiles within each well correlate to the overall performance of the pair. SAGD is a low-pressure process that is sensitive to reservoir heterogeneity and other factors, hence accurate simulation of in situ wellbore pressures is critical for both mitigating uneven steam chamber evolution and optimizing wellbore design and operation. Recently published horizontal drift-flux correlations have been implemented in a commercial thermal reservoir simulator with a multi-segment well model. Valid for horizontally drilled wells with undulations, they complement previously reported drift-flux models developed for vertical and inclined wells down to approximately 5 degrees from horizontal. The formulation of these correlations has a high degree of nonlinearity. These models are tested in simulations of SAGD field operations. First, an overview of drift-flux models is discussed. This differentiates those based on vertical flow with gravity segregation to those that model horizontal flow with stratified and slug flow regimes. Second, the most recent and significant drift-flux correlation by Bailey et al. (2018, and hereafter referred to as Bailey-Tang-Stone) was robustly designed to be used in the well model of a reservoir simulator, can handle all inclination angles and was optimized to experimental data from the largest available databases to date. This and earlier drift-flux models are reviewed as to their strengths and weaknesses. Third, governing equations and implementation details are given of the Bailey-Tang-Stone model. Fourth, six case studies are presented that illustrate homogeneous and drift-flux flow model differences for various well scenarios.

scholarly journals Comparison Between Homogenous and Heterogeneous Reservoirs: A Parametric Study of Water Coning Phenomena

2021 ◽  
Vol 5 (1) ◽  
pp. 119-131
Author(s):  
Frzan F. Ali ◽  
Maha R. Hamoudi ◽  
Akram H. Abdul Wahab
Keyword(s):  
Production Rate ◽  
Oil Production ◽  
Water Production ◽  
Effective Parameters ◽  
Radial Cross Section ◽  
Heterogeneous Reservoirs ◽  
Water Breakthrough ◽  
Water Coning ◽  
Water Cut ◽  
Reservoir Simulator

Water coning is the biggest production problem mechanism in Middle East oil fields, especially in the Kurdistan Region of Iraq. When water production starts to increase, the costs of operations increase. Water production from the coning phenomena results in a reduction in recovery factor from the reservoir. Understanding the key factors impacting this problem can lead to the implementation of efficient methods to prevent and mitigate water coning. The rate of success of any method relies mainly on the ability to identify the mechanism causing the water coning. This is because several reservoir parameters can affect water coning in both homogenous and heterogeneous reservoirs. The objective of this research is to identify the parameters contributing to water coning in both homogenous and heterogeneous reservoirs. A simulation model was created to demonstrate water coning in a single- vertical well in a radial cross-section model in a commercial reservoir simulator. The sensitivity analysis was conducted on a variety of properties separately for both homogenous and heterogeneous reservoirs. The results were categorized by time to water breakthrough, oil production rate and water oil ratio. The results of the simulation work led to a number of conclusions. Firstly, production rate, perforation interval thickness and perforation depth are the most effective parameters on water coning. Secondly, time of water breakthrough is not an adequate indicator on the economic performance of the well, as the water cut is also important. Thirdly, natural fractures have significant contribution on water coning, which leads to less oil production at the end of production time when compared to a conventional reservoir with similar properties.

A Nine-Point, Finite-Difference Reservoir Simulator for Realistic Prediction of Adverse Mobility Ratio Displacements

1979 ◽  
Vol 19 (04) ◽  
pp. 253-262 ◽  
Author(s):  
J.L. Yanosik ◽  
T.A. McCracken
Keyword(s):  
Finite Difference ◽  
Oil Recovery ◽  
Mobility Ratio ◽  
Spot Pattern ◽  
Oil Saturation ◽  
Grid Systems ◽  
Displacement Front ◽  
Grid Orientation ◽  
Recovery Performance ◽  
Reservoir Simulator

Abstract Reservoir simulators based on five-point difference techniques do not predict the correct recovery performance for unfavorable mobility-ratio, piston-type performance for unfavorable mobility-ratio, piston-type displacements. For a developed five-spot pattern, the predicted performance depends on the grid orientation predicted performance depends on the grid orientation (parallel or diagonal) used. This paper discusses the development and testing of a nine-point, finite-difference reservoir simulator. Developed five-spot-pattern flood predictions are presented for piston-type displacements predictions are presented for piston-type displacements with mobility ratios ranging from 0.5 to 50-0. We show that the predicted fronts are realistic and that very little or no difference exists between the results of parallel and diagonal grids. The maximum difference in the recovery curves is less than 1.5 %. The nine-point-difference method is extended to any grid network composed of rectangular elements. Results for two example problems - a linear flood and a direct line-drive flood - indicate the extension is correct. The techniques discussed here can be applied directly in the development of any reservoir simulator. We anticipate that the greatest utility will be in the development of simulators for the improved oil-recovery processes that involve unfavorable mobility ratio processes that involve unfavorable mobility ratio displacements. Examples are miscible flooding, micellar/ polymer flooding (water displacing polymer), and direct polymer flooding (water displacing polymer), and direct steam drive. Introduction Miscible displacement oil-recovery methods often are characterizedby a large viscosity ratio between the oil and its miscible fluid andby a very low immobile oil saturation behind the displacement front. These conditions represent an unfavorable mobility-ratio, piston-type displacement. They differ from a conventional piston-type displacement. They differ from a conventional gas drive, where a substantial mobile oil saturation remains behind the displacement front. Reservoir simulators based on five-point, finitedifference techniques do not predict the correct performance for unfavorable mobility-ratio, piston-type performance for unfavorable mobility-ratio, piston-type displacements. Results of an areal simulation for a developed five-spot flood depend on the grid orientation (diagonal or parallel, Fig. 1). Grid orientation significantly influences the predicted recovery performance and displacement front positions. performance and displacement front positions. A nine-point, finite-difference reservoir simulator is described. Predictions of piston-type displacements in a developed five-spot pattern are presented for mobility ratios ranging from 0.5 to 50. We show that the predicted fronts are realistic and that very little or no predicted fronts are realistic and that very little or no difference exists between the results of parallel and diagonal grid orientations. A formulation of the nine-point, finite-difference technique applicable to any rectangular grid network is presented. Results for two example two-dimensional presented. Results for two example two-dimensional problems, a linear flood, and a direct line-drive flood problems, a linear flood, and a direct line-drive flood indicate that the formulation is correct for nonsquare grid networks. Background Grid-orientation effects for five-point reservoir simulators were demonstrated by Todd et al. They studied two developed five-spot grid systems - a diagonal grid and a parallel grid. These grid systems are shown in Fig. 1. parallel grid. These grid systems are shown in Fig. 1. The diagonal grid represents a quarter of a five-spot pattern, with grid lines at 45 degrees to a line connecting the pattern, with grid lines at 45 degrees to a line connecting the injector and producer. The parallel grid represents one-half of a five-spot pattern, with grid lines either parallel or perpendicular to the lines connecting the parallel or perpendicular to the lines connecting the injector-producer pads. SPEJ P. 253

Stabilized Water-Cut in Carbonate Naturally-Fractured Reservoirs With Bottom Water With an Implication in Well Spacing Design for Recovery Optimization

2018 ◽  
Author(s):  
Samir Prasun ◽  
A. K. Wojtanowicz
Keyword(s):  
Final Stage ◽  
Bottom Water ◽  
Fractured Reservoirs ◽  
Capillary Forces ◽  
Naturally Fractured Reservoirs ◽  
Oil Displacement ◽  
Well Spacing ◽  
Constant Rate ◽  
Water Coning ◽  
Water Cut

Maximum stabilized water-cut (WC), also known as ultimate water-cut in a reservoir with bottom-water coning, provides important information to decide if reservoir development is economical. To date, theory and determination of stabilized water-cut consider only single-permeability systems so there is a need to extend this concept to Naturally Fractured Reservoirs (NFRs) in carbonate rocks — known for severe bottom water invasion. This work provides insight of the water coning mechanism in NFR and proposes an analytical method for computing stabilized water-cut and relating to well-spacing design. Simulated experiments on a variety of bottom-water hydrophobic NFRs have been designed, conducted, and analyzed using dual-porosity/dual-permeability (DPDP) commercial software. They show a pattern of water cut development in NFR comprising the early water breakthrough and very rapid increase followed by water cut-stabilization stage, and the final stage with progressive water-cut. The initial steply increase of water-cut corresponds to water invading the fractures. The stabilized WC production stage occurs when oil is displaced at a constant rate from matrix to the water-producing fractures. During this stage water invades matrix at small values of capillary forces so they do not oppose water invasion. In contrast, during the final stage (with progressing water cut) the capillary forces grow significantly so they effectively oppose water invasion resulting in progressive water cut. A simple analytical model explains the constant rate of oil displacement by considering the driving effect of gravity and viscous forces at a very small value of capillary pressure. The constant oil displacement effect is confirmed with a designed series of simulation experiments for a variety of bottom-water NFRs. Statistical analysis of the results correlates the duration of the stabilized WC stage with production rate and well-spacing and provides the basis for optimizing the recovery. Results show that stabilized water-cut stage does not significantly contribute to recovery, so the stage needs to be avoided. Proposed is a new method for finding the optimum well spacing that eliminates the stabilized WC stage while maximizing recovery. The method is demonstrated for the base-case NFR.

A Study to Prevent Bottom Water From Coning in Heavy-Oil Reservoirs: Design and Simulation Approaches

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Binshan Ju ◽  
Xiaofeng Qiu ◽  
Shugao Dai ◽  
Tailiang Fan ◽  
Haiqing Wu ◽  
...  
Keyword(s):  
Heavy Oil ◽  
Bottom Water ◽  
Horizontal Wells ◽  
Oil Well ◽  
Vertical Wells ◽  
Water Contact ◽  
Water Columns ◽  
Heavy Oil Reservoirs ◽  
Oil Water ◽  
Downhole Water Sink

The coning problems for vertical wells and the ridging problems for horizontal wells are very difficult to solve by conventional methods during oil production from reservoirs with bottom water drives. If oil in a reservoir is too heavy to follow Darcy’s law, the problems may become more complicated for the non-Newtonian properties of heavy oil and its rheology. To solve these problems, an innovative completion design with downhole water sink was presented by dual-completion in oil and water columns with a packer separating the two completions for vertical wells or dual-horizontal wells. The design made it feasible that oil is produced from the formation above the oil water contact (OWC) and water is produced from the formation below the OWC, respectively. To predict quantitatively the production performances of production well using the completion design, a new improved mathematical model considering non-Newtonian properties of oil was presented and a numerical simulator was developed. A series of runs of an oil well was employed to find out the best perforation segment and the fittest production rates from the formations above and below OWC. The study shows that the design is effective for heavy oil reservoir with bottom water though it cannot completely eliminate the water cone formed before using the design. It is a discovery that the design is more favorable for new wells and the best perforation site for water sink (Sink 2) is located at the upper 1/3 of the formation below OWC.

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