bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geological Sequestration of Carbon Dioxide in Depleted Gas Reservoirs
Authors: Sobers L. E. , Frailey S. M. , Lawal A. S. 
Published: December 2007

Abstract
The purpose of this paper is to investigate the effects of phase behavior on the sequestration CO2 of in depleted gas reservoirs (dry gas, wet gas and retrograde gas). Carbon dioxide sequestration in depleted and abandoned gas reservoirs can accomplish two important objectives. Firstly, it could be important part of present climate control initiative to reduce the concentration of carbon dioxide in the atmosphere. Secondly, it could be instrumental to enhance gas and condensate recovery. Using the pressure-temperature diagrams and two phase flash calculations, the phase behavior of natural gas-carbon dioxide mixtures were analyzed to provide enlightenment on the sequestration process. From analysis of simulated results, it was found that carbon dioxide exhibited a drying effect on wet and retrograde gas mixtures and a wetting effect on dry gas. The results for retrograde gas condensate depended on the composition of reservoir fluids at abandonment conditions. The main difference being the liquid volume present with increasing pressure and carbon dioxide concentration. This influenced the volume of condensate vaporized with addition of carbon dioxide. It was also determined that carbon dioxide lowers the compressibility factor of all gas types. These results are favorable for carbon dioxide sequestration because decreasing compressibility factors represents increasing storage capacity.
Improved Mappings for Streamline-Based Simulation
Authors: Mallison B. T. , Gerritsen M. G. , Matringe S. F. 
Published: December 2007

Abstract
Our interest lies in extending the streamline method compositional simulation. In this paper we develop improved mappings to and from streamlines that are necessary to obtain reliable predictions of gas injection processes. Our improved mapping to streamlines utilizes a piecewise linear representation of saturations on the background grid in order to minimize numerical smearing. Our strategy for mapping saturations from streamlines to the background grid is based on Kriging. We test our improvements to the streamline method using a simple model for miscible flooding based on incompressible, Darcy flow. Results indicate that our mappings offer improved resolution and reduce mass balance errors relative to the standard mappings. Our mappings also require fewer streamlines to achieve a desired level of accuracy. In compositional cases where the computational cost of a streamline solve is high, we anticipate that this will lead to significant improvement in the efficiency of streamline-based simulation.
Experimental Study of Tertiary Immiscible WAG Injection
Authors: Righi E. Fernández , Royo J. , Gentil P. , Castelo R. , Del Monte A. , Bosco S. 
Published: December 2007

Abstract
An experimental study of immiscible WAG (water-alternating gas) injection is presented. The target reservoir is the waterflooded Troncoso sandstone in Chihuido de la Sierra Negra Field in Argentina. The original reservoir fluid was an undersaturated light oil with a viscosity of about 1 cp and 13 to 20 mole percent carbon dioxide.
Phase behavior tests were conducted using live reservoir oil and synthetic candidate injection gases. They were aimed at assessing the extent to which compositional effects could affect oil recovery at current reservoir pressure.
Coreflooding experiments were performed on field core composites using current field production gas which has 65 mole % CO2. The samples were initially saturated with live oil and irreducible formation water and then flooded with formation water to residual oil saturation at reservoir conditions. Following waterflood, a number or WAG cycles were injected. The displacements were conducted at pressures well below the estimated minimum miscibility pressure for this system.
Tertiary oil recovery efficiency resulting from WAG injection was significant, leading to final residual oil saturations as low as 13 % pore volume (PV). Results of corefloods and compositional laboratory tests suggest that the displacement mechanism is a combination of compositional effects and fluid mechanical effects. The former include interfacial tension reduction, oil swelling and viscosity reduction. Mechanical, fluid distribution effects result from the presence of the free gas phase in the pore system and the cyclic variation in gas and water saturations, as accounted for in a recently developed immiscible WAG phenomenological model that has been used to simulate the process presented here.
Streamline Technology for the Evaluation of Full Field Compositional Processes; Midale, A Case Study
Authors: McKishnie R. A. , Malik S. , Chugh S. , Lavoie R. G. , Griffith P. J. 
Published: December 2007

Abstract
Traditionally, the evaluation of CO2 flooding processes is performed using finite difference compositional simulation models. However, compositional simulation is impractical for modeling large-scale CO2 floods due to computational runtime restrictions. In cases where reservoir heterogeneity and fluid mobility dominate the reservoir recovery mechanism, streamline simulation offers a viable alternative to compositional simulation. The "reduced" physics in streamline simulation allows field scale CO2 flood modeling to be feasible, as long as the streamline PVT model can be calibrated such that the streamline model will produce accurate results for CO2 injection processes. Using streamline simulation allows for the evaluation of multiple full field development scenarios that would otherwise not be possible using compositional simulation.
The objective of the study was to provide CO2 flood performance forecasts under various full field development scenarios for the Midale field. This paper focuses on the methodology and results from the 1000 well, &gt;400,000 grid blocks, and 45+ years of history streamline simulation of the Midale field. In particular, it discusses the construction and history match of the full field model, calibration of the streamline model with the compositional model and development of the full field CO2 forecasts.
Improved Oil Recovery by In-fill Drilling in a Mature Field; A Success Story
Authors: Ghosh B. N. , Sarkar Soma. D. , Lohiya J. P. , Das T. K. 
Published: December 2007

Proposal
North Kadi oil field in North Cambay Basin, India has been under production since 1969. The hydrocarbon accumulation in the field is mainly in Middle Miocene sandstone of Kalol Formation having high permeability and strong aquifer support. The development plan of the reservoir had been drawn on the basis of simulation studies carried out at various stages. Recently, remodeling of the field has been done for rational exploitation of the reservoirs.
Improved Oil Recovery (IOR) Scheme was formulated after updating the geological model. In-fill drilling of 33 locations were firmed up to achieve the optimal recovery. It envisaged 1.7% additional recovery of in-place oil in 20 years over the primary component of 31.23%. At the time of implementation of the scheme, the field had already produced 20% of 67.0 MMt OIIP. Thirty two IOR locations have been drilled during last three years. As of now, the incremental production from IOR wells is 26% higher than envisaged production profile. The in-fill wells have shown no interference on the performance of nearby wells within their past two years of production history.
The drilling and completion cost of the wells break-evened in 20 months. The IOR Scheme involving in-fill drilling rejuvenated the declining trend of a mature oil field.
Enhanced Oil Recovery with Horizontal Waterflooding, Osage County, Oklahoma
Authors: Westermark R. V. , Dauben D. , Robinowitz S. , Weyland H. V. 
Published: December 2007

Abstract
This paper provides details of a project to test horizontal waterflooding as a means of improved oil recovery in Osage County, OK. Supported by a grant from the Department of Energy (DOE), an independent operator, Grand Resources, Inc., has developed a process for selecting and developing candidate reservoirs for horizontal waterflooding. Reservoir screening is the first step in the process and then rock mechanics are used to predict wellbore stability for determining the most efficient completion method. Geologic and reservoir parameters are considered when selecting the radius of curvature for the horizontal well to be drilled and the air/foam drilling fluids to be utilized to avoid formation damage. The final step is to run a comprehensive set of logs through the curve and out into the reservoir allowing for petrophysical evaluation.
To accomplish an economically successful project, given the basic assumption of an existing field infrastructure having an adequate water supply well available, the following three goals must be met: 1) demonstrate that horizontal waterflooding is technically and economically feasible for recovering additional oil in shallow low permeability reservoirs; 2) demonstrate that open hole completions are a viable technique based on wellbore stability considerations; 3) demonstrate that short radius rotary steerable technology can drill horizontal wells at low cost and without reservoir damage.
A New Way to Diagnose Injectivity Decline During Fractured Water Injection By Modifying Conventional Hall Analysis
Authors: Ojukwu K. I. , van den Hoek P. J. 
Published: December 2007

Abstract
For many years, unfiltered produced water has been used in the flooding of heavy oil reservoir in Southern Oman for pressure maintenance. Initially it was thought that the water injection was under matrix conditions. However, it is well accepted in the industry that water injection and particularly produced water injection almost, always takes place under fracturing condition. Significant decline in injectivity was repeatedly seen due to downhole blockages. Routine clean-ups and acidizations were carried out without success. Early 2003, a dedicated study was conducted to identify the root cause of this problem and recommend a remedial action. The purpose was to determine if the decline is due to poor water quality, reservoir compartmentalization, matrix/fracture or wellbore plugging.
An unconventional approach was used to conduct a comprehensive study using historical data by modifying the Hall-Analysis technique. It was concluded that poor water quality was the problem. The interpretation of the Modified Hall Plot together with Bottomhole Pressure (BHP) vs. Rate plot also provided evidence of wellbore and/or fracture plugging. Both qualitative and quantitative analyses characterized the initial matrix injection period and fracturing injection regime that followed. Fracture plugging, routine well stimulations and fracture propagation trends were interpreted from the plots. A 3D in-house simulation package for waterflood under fracturing conditions was used, independently, to simulate injection conditions and confirm the results. Simulated injection pressure was much lower than actual field data confirming severe plugging. Further analysis showed that the plugging was due to unconventional particulates different from solids and oil contaminants in water. Recommendation was made to identify the contaminant and maintain a maximum suspended solid concentration of 100ppm to contain fracture propagation. A recent filter trial confirmed the presence of FeS contaminant.
Successful remedial action was taken followed by recommissioning and water treatment facility design to realize estimated 150m3/d/well and improving ultimate recovery. Recently, another field study has successfully completed adopting same technique. By modifying Hall Analysis technique, it is possible to use field data for diagnosing matrix/fracturing regimes, assessing degree of damage and determining the location of the damage.
Cyclic Water Injection Simulations for Evaluations of its Potential in Lagocinco Field
Authors: Stirpe M. T. , Guzman J. , Manrique E. , Alvarado V. 
Published: December 2007

Abstract
Cyclic Water Injection (CWI) has been proposed as a technique to improve water sweep in stratified and fractured reservoirs. This recovery process takes advantage of the pressure transient response in regions of different permeability, leading to forced imbibition of the lesser permeable layers, in the case of stratified reservoirs. A process such as this is expected to yield an additional recovery between 2 and 7% over continuous waterflooding and a significant reduction in watercut, reason why it has been proposed as a zero cost EOR process, wherever facilities for water injection are already available. Several mechanisms have been attributed the additional oil production, among which are listed pressure differences between layers with limited communication and hysterisis of the capillary pressure and relative permeability curves. Here we have taken a full-field model of an extensively investigated reservoir of Western Venezuela, the VLE-305, located in the Lagocinco field to analyze some of the critical variables of the process and determine the potential for cyclic water flooding. The reservoir has been proposed as a candidate for immiscible WAG injection and a successful pilot test has been carried out. This deep, stratified sandstone reservoir meets the characteristics sought in cyclic water injection projects. In recent work, it was shown that some potential exists for water cyclic injection in the WAG pilot area. Production history of the field has been used to help with the analysis of critical variables of this process, including injector-to-producer well distance and reservoir pressure relative to the bubble point pressure, among others. Additionally, a recently developed analytical model of the process was also tested to determine its potential as a fast evaluation tool for CWI. Results show that permeability trends, reservoir pressure, well distance and water saturation at the startup of the process have high impact on the potential additional recovery, leading to recommendations for the application schedule of the process.
Improve Injection Profile by Combining Plugging Agent Treatment and Acid Stimulation
Authors: Zhao Puchun , Zhao Huating , Bai Baojun , Yang Xinming 
Published: December 2007

Abstract
Plugging agent treatment and acid stimulation has completely different mechanisms for improving injection profiles. In this paper, a hybrid procedure is introduced to reduce the damage of plugging agent to low and medium permeability zones and the penetration radius of acid into high permeability zones. The procedure is: first inject plugging agent to block high permeability zones, and then inject acid to remove plugging agent damage from the low and medium permeability zones and stimulate them. For performing this procedure successfully, three kinds of plugging agents were screened out for using in different reservoirs:
Strong strength plugging agent for the wells with fractures or high permeability streaks;
Weak gel for those with thick layer in which serious heterogeneity exists;
Temporary plugging agent for those in which the absorption ability of high permeability zones needs maintaining.
Several acid systems were evaluated to be compatible with the three kinds of plugging agents.
The objectives of this paper are: (1) To show the screen results about the compatible plugging agent and acid; (2) To show how to optimize the operation process; (3) To tell some experiences learnt from the oilfield applications of this technique.
From Jan. 2001 to Dec. 2002, 46 operations using this procedure were carried out in Weicheng and Mazhai Oilfields of SINOPEC. Results show that the average benefit/cost ratio is over 3.5. Experience learnt from these applications was summarized in the paper.
Foam Displacements With Multiple Steady States
Authors: Rossen W. R. , Bruining J. 
Published: December 2007

Abstract
A number of experimental and theoretical studies suggest that the fractional-flow function for foam can be either multivalued in water saturation or else comprise distinct fractional-flow curves for two or more foam regimes, with jumps between them where each regime reaches its limiting condition. We construct fractional-flow solutions for these cases. When such a foam is employed in a surfactant-alternating-gas (SAG) process, the usual "tangency" condition is modified and the foam can be considerably weaker than the foam formed at what appears to be the point of tangency of the multi-valued fractional-flow function. If the capillary-pressure function differs between foam regimes, that difference can substantially change the nature of the displacement. This alters the effective fractional-flow function and hence the global solution of the equations. It is therefore important to determine how capillary pressure varies in foam displacements, by direct measurement in situ if possible. Special care is needed in numerical simulation of processes using fixed grids if capillary pressure depends directly on foam regime. Using grid blocks that are too large can weaken the effect of capillary pressure enforcing the correct shock on the small scale. Using an upscaled fractional-flow function appears to eliminate this problem, however.
A Simple Approximate Method to Predict Inflow Performance of Selectively Perforated Vertical Wells
Authors: Guerra E. , Yildiz T. 
Published: December 2007

AbstractThis paper presents an approximate model to forecast the productivity of selective perforated wells. The model includes algebraic equations and it could be easily computed using a programmable calculator or spreadsheet program. The model has been compared against the rigorous 3D semi-analytical model and software existing in the literature. The approximate model compares well against the 3D model and the software. The model is useful for designing perforation parameters.
Application of DLVO Theory to Characterize Spreading in Crude oil-Brine-Rock Systems
Authors: Busireddy Chandrasekhar , Rao Dandina N. 
Published: December 2007

Abstract
The presence of thin aqueous films and their stability has a profound effect on reservoir rock-fluids interactions involving spreading and adhesion. The stability of thin wetting aqueous films on rock surfaces is governed by several variables including pH, brine and crude oil compositions, and capillary pressure. These variables govern the wetting states in the solidliquid-liquid systems. The wetting states influence the residual oil saturation and the oil-water relative permeabilities and consequently the oil recovery.
The objective of this study is to deduce a functional dependence of thin film stability on the above parameters by considering intermolecular and surface interactions in crude oil-brine-rock systems. The surface forces are manifested as disjoining pressure in thin films. The disjoining pressure isotherms for the selected solid-liquid-liquid system have been computed in terms of the bulk properties of the media. The equilibrium contact angles have also been computed from the integration of the Young-Laplace equation, which relates contact angle to the capillary pressure and disjoining pressure isotherms of the system. The contact angle data obtained from sessile drop experiments have been compared with the calculated results as well as with other published results. Adhesion maps, which relate the film stability to brine pH and molarity, have been developed.
The rock-fluids system considered for study consisted of smooth Glass, Quartz and Yates reservoir fluids. The DLVO theory has been used to model the intermolecular forces. The structural forces are incorporated to overcome the limitations of the DLVO theory. A charge regulation model was used to analyze the crude oil-brine and Glass-brine interfaces. The effects of multivalent ions have been incorporated by an equivalent molarity concept. The overall computational model being developed in this study is aimed at providing a-priori prediction capability of rock-fluids interactions in petroleum reservoirs for inclusion in reservoir simulators.
Adomian Solution of Forchheimer Model to Describe Porous Media Flow
Authors: Belhaj Hadi , Biazar Jafar , Butt Stephen , Islam Rafiq 
Published: December 2007

Abstract
Currently, fluid flow in porous media is mostly calculated by utilizing the well known diffusivity equation based on Darcy’s law. This diffusivity equation is the core fluid flow equation in all modern reservoir simulators used to predict flow behaviors. Inaccurate predictions of reservoir simulators have been reported nevertheless, history matching has been achieved. This dilemma led to questioning the adequacy of the basic governing equation of fluid flow behavior in porous media.
This paper suggesting a new governing equation that includes Darcy’s viscous term, Forchheimer’s inertial term and Brinkman’s viscous term all in one model called the Modified Brinkman Model "MBM". MBM proven to accurately describe fluid flow in porous media in both Darcian and non-Darcian domains and can be used in both oil and gas reservoirs for both matrix and fracture systems. A genuine mathematical solution "Adomian decomposition technique" has been successfully employed to solve the partial differential model with great deal of accuracy and ease. The proposed MBM is expected to have wide applications in oil, gas and underground water reservoirs.
Laboratory Investigation of Stress-Sensitivity of Non-Darcy Gas Flow Parameters
Authors: Zeng Zhengwen , Grigg Reid B. , Gupta D. B. 
Published: December 2007

Abstract
Non-Darcy flow parameters were investigated in 159 series of high pressure/high temperature/high velocity gas flooding experiments on five different rock samples under field reservoir conditions. The results of these experiments reconfirm and extend to new conditions that permeability increase, while non-Darcy flow coefficient decreases with effective stresses; both are independent of shear stresses. General formulas have been developed to quantify the stress-sensitivity in terms of nominal non-Darcy parameters. General equations have been proposed to predict the change of permeability and non-Darcy flow coefficient with given effective stresses and nominal non-Darcy flow parameters.
Modelling Asphaltene Precipitation and Deposition in a Compositional Reservoir Simulator
Authors: Kohse Bruce F. , Nghiem Long X. 
Published: December 2007

Abstract
This paper describes asphaltene precipitation and deposition models implemented in a compositional reservoir simulator. The asphaltene precipitate is modelled as two solids: Solid 1 is thermodynamically reversible and is in equilibrium with the asphaltene component in the oil phase. Solid 2 is created from Solid 1 via a chemical reaction. Solid 2 can be used to represent the flocculation of smaller precipitated asphaltene particles into larger aggregates. This aggregation can be made fully reversible, fully irreversible or partially irreversible. Solid 1 flows as suspended particles in the oil phase, while Solid 2 may flow with the oil or deposit in the rock matrix.
The deposition model incorporates surface deposition, pore-throat plugging and re-entrainment of deposited solid into the flowing liquid phase. Porosity and permeability impairment due to asphaltene deposition are also modelled. Model results are compared to laboratory core floods illustrating core damage due to asphaltene deposition. The model is also applied to studies of primary depletion, and core flood simulations of miscible gas injection for light oils.