bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lessons from the First Successful Oil Producer Multistage Acid Fracturing in Saudi Arabia: The QA/QC Process from the Laboratory to the Field
Authors: Almubarak Tariq , Bataweel Mohammed , Rafie Majid , Said Rifat , Al-Ibrahim Hussain , Osode Peter , Alfaifi Mohammed , Alenizi Sultan , Aldajani Omar , Karadkar Prasad 
Published: June 2014

Abstract
The increasing demand for energy has extended the development horizon towards relatively tighter formations. However, experience has shown that the most successful technique to optimize production from these tight carbonate formations would require multistage acid fracture stimulation treatment. Generally, laboratory tests, computer simulation and technical expert opinions yield optimistic results which are not always replicated in the field due to the absence of strong QA/QC follow-up. This field support was considered critical for a recent multi stage acid fracture treatment which involved many variables and fluid additives in an onshore Saudi Arabia multi-lateral well. This report will discuss the pre-job laboratory tests and fluid optimization process which included core flooding, compatibility, stability, and rheology tests. In addition, this paper will outline the QA/QC process adopted throughout the various operational stages and provide flowchart as recommendations for subsequent multistage acid fracture treatments in the field. Also presented is a case study from the first successful oil field multistage acid fracture treatment in Saudi Arabia.
Laboratory results obtained reflected the negative impact of increased salinity on the crosslinked viscosity. In addition, a new low temperature-instant crosslinker was evaluated as an alternative which resulted in higher viscosity and faster break time. Further laboratory tests showed the sensitivity of the emulsifier used to mix emulsified acid and this led to corrective changes to the on-site mixing process. These and many other operational adjustments enabled bridging the gap between laboratory design and field implementation, thereby ensuring a successful acid fracturing treatment.
Optimization and Post-Job Analysis of the First Successful Oil Field Multistage Acid Fracture Treatment in Saudi Arabia
Authors: Almubarak Tariq , Bataweel Mohammed , Rafie Majid , Said Rifat , Al-Ibrahim Hussain , Al-Hajri Mohammad , Osode Peter , Al-Rustum Abdullah , Aldajani Omar 
Published: June 2014

Abstract
Multistage acid fracture treatments are utilized in low-permeability carbonate reservoirs (permeability &lt;10 md) to stimulate the formation by creating highly conductive fractures in the formation and bypassing near wellbore damage. The fracture is generated at high pressures that are required to break the rock open while using a viscous pad. The fracture is then kept open by adding gelled or emulsified acid to create uneven etches on the surface of the fracture.
Pre-job acid fracturing treatment fluids’ reaction and compatibility analysis in the laboratory are crucial as the operational success is highly dependent on its chemicals’ reactions. The key problem with acid fracturing treatments is the difficulty in appraising the actual downhole reactions and performance of the treatment chemicals within the heterogeneous rock. This problem can be resolved when flow back fluids and the chemical ions are analyzed to understand the reactions that occurred down hole. Also, since acid fracture treatments require pumping large volume of fluids, flowing back the entire fluids becomes a challenge due to the low reservoir permeability and the associated reservoir rock capillary pressure effects.
This paper will discuss the pre-fracture treatment evaluation based on laboratory experiments - core flood, rock dissolving capacity, and fluid compatibility in addition to comparing the expected chemical ion returns with the actual ions observed in the flow-back fluids.
The results of this flow-back fluid analysis showed a recovery of 17% of the chemicals pumped during the treatment with a stabilized production rate of 3 MBOPD. Further water analysis indicated the presence of 25-30% formation water while the critical ions analyzed showed the effectiveness of the corrosion inhibitor package, acid system dissolving capacity, and crosslinker fluid recovery. It is expected that this paper will provide a learning process for optimizing future multistage acid fracture treatment in Saudi Arabia.
Pressure-Up Blowdown Combustion: A Channeled Reservoir Recovery Process
Authors: Hallam R. J. , Donnelly J. K. 
Published: June 2014

Summary
The cyclic pressure-up blowdown combustion process was developed as a follow-up to cyclic steam stimulations that used fracturing to create injectivity. The process was designed to exploit a reservoir that had a high contrast between the mobility of the heated channels, left as a remnant of the cyclic steam operations, and the adjacent cold reservoir. The combined process of cyclic steam followed by combustion has the potential to achieve a recovery factor of about 30%.
A New Semi-Analytical Method for Numerical Simulation of Fluid and Heat Flow in Fractured Reservoirs
Authors: Pruess Karsten , Wu Yu-Shu 
Published: June 2014

ABSTRACT
Permeability and flow in many petroleum, gas, and geothermal reservoirs are dominated by fractures. Despite major advances in recent years, mathematical modeling of fluid and heat flow in fractured reservoirs remains a difficult problem. Porous medium approximations have been shown to be inadequate for many flow processes in fractured systems, while double- or multiple-porosity techniques may involve excessive amounts of numerical work or large discretization errors.
We have developed a new method for modeling fluid and heat flow in fractured reservoirs which is an extension of a technique developed by Vinsome and Westerveld (1980), for calculating heat exchange between permeable layers and impermeable semi-infinite confining beds during thermally enhanced oil recovery. Our method combines a finite-difference description of global flow in the fractures with an analytical representation of interporosity flow by means of trial functions for fluid pressures and temperatures in the matrix blocks. The trial functions contain adjustable parameters which are calculated for each time step in a fully coupled way based on matrix block shapes and dimensions, utilizing simple mass and energy conservation principles.
We have incorporated the semi-analytical technique into our general-purpose multiphase simulator MULKOM. The method was verified by comparison with exact analytical solutions for fluid and heat exchange with individual matrix blocks. Applications were made to geothermal well test and production-injection problems with interporosity fluid and heat flow. The calculations show excellent agreement with numerical simulations using the method of "multiple interacting continua" (MINC), with no noticeable increase in computing work compared to porous medium calculations.
Simulation of Miscible Viscous Fingering Using a Modified Method of Characteristics: Effects of Gravity and Heterogeneity
Authors: Moissis D. E. , Wheeler M. F. , Miller C. A. 
Published: June 2014

ABSTRACT
The effects of gravity and of the structure of the porous medium on unstable miscible displacement are studied by means of numerical simulation. The numerical method combines a modified method of characteristics with a mixed finite element method. The permeability fields used in the simulations are generated by a statistical method so that they have a given coefficient of variation and a given correlation length.
Results indicate that a displacement may be dominated by gravity override or by viscous fingering or both mechanisms may be important. When gravity tonguing is dominant, the results are early breakthrough and little oil recovery after breakthrough.
Finger generation is governed by the permeability distribution near the inflow end. Shielding and merging during the displacement reduce the initial number of fingers to a smaller number of "active fingers", which dominate the displacement. The number of active fingers is a decreasing function of the correlation length, the coefficient of permeability variation and the viscosity ratio, but, with these parameters fixed, it is largely independent of the specific permeability distribution. The root mean square growth rate of the fingers stays approximately constant throughout the displacement; its value is an increasing function of the viscosity ratio and coefficient of variation, while its dependence on the correlation length is of a more complex character.
Thermally Stable Gels for Near-Wellbore Permeability Contrast Corrections
Authors: Moradi-Aragbx A. , Bjornson G. , Doe P. H. 
Published: June 2014

ABSTRACT
The application of metallic or organic crosslinkers for gelation of polyacrylamides or polysaccharides is limited to relatively low temperatures and hardness levels. These polymers will initially produce good gels under hostile environment conditions (Hardness &gt; 200 ppm, Temperature&gt;167°F (75°C)), but the acrylamide gels undergo substantial syneresis due to the hydrolysis of the amide groups followed by additional crosslinking with the divalent cations present in the brine. Due to chain scission of the inherently weak ether linkages in the polymer structure, polysaccharide gels do not survive extended aging under hostile environment conditions.
Copolymerization of acrylamide with other monomers can provide protection against excessive thermal hydrolysis. These acrylamide containing polymers can be crosslinked with mixtures of phenolic compounds and formaldehyde to produce gels which are tolerant to the harsh conditions common to most deeper reservoirs. The gels produced by the reaction of these polymers with phenol and formaldehyde in a brine such as seawater containing 3.4% TDS and 1700 ppm hardness have survived over 2 1/2 years of aging at 235°F (113°C). A similar gel had survived over 9 months of aging at 300°F (149°C) in seawater when the test was terminated.
Metallic crosslinkers such as Cr(III) produced in-situ, when used in conjunction with a different thermally stable polymer, resulted in the formation of a stable gel in a brine containing 2.45% TDS and 1, 555 ppm Ca(II). This gel had survived 2 years of aging at 220°F (104°C) before the test was terminated. A similar gel made with polyacrylamide began to synerese within a month and shrank more than 80% in less than three months of aging at 200°F (93°C).
A producing oil well with a bottomhole temperature of 230°F (110°C), treated with organic crosslinking of a thermally stable polymer, has produced over 33, 000 bbls of incremental oil in 54 months since the treatment.
Three-Phase Studies of Gas-Condensate Flow Behavior
Authors: Fishlock T. P. , Smith R. A. K. 
Published: June 2014

Summary
Experiments have shown that an oil phase introduced by condensation reduces gas relative permeability in the presence of an immobile water saturation. Such an oil phase, however, reduces both the waterflood residual gas saturation and the critical gas saturation for remobilization by depressurization after a waterflood almost to the extent of the oil-phase saturation.
An Analytical Solution for Steam/Oil/Water Displacements
Authors: Wingard J. S. , Orr F. M. 
Published: June 2014

SUMMARY
Analytical solutions, obtained by the method of characteristics, are reported for displacement of oil and water by injected steam in one dimension. We describe a mathematical model of purely convective flow of two or three phases with temperature variation. The model includes effects of volume change with changes of temperature and phase but excludes efFects of longitudinal conduction or transverse heat loss. We outline the formulation of the resulting eigenvalue problem, and we state and solve the shock balances that are an essential part of the solutions.
We report and compare example solutions for displacement of two oils. The first is a light oil, and the second is an oil with a high viscosity and a strong temperature dependence. The solutions obtained show a steam/oil zone near the injection end, an oil/water zone at the downstream end, and a three-phase steam/oil/water zone in between. We show, for the oil properties and relative permeabilities used, (1) that the steam saturation in the steam/oil zone and the three-phase region is a strong function of oil viscosity, (2) that the overall flow velocity is nearly constant except at shocks where the number of phases change, and (3) that the formation of an oil bank ahead of the three-phase region is possible only for a sufficiently viscous oil.
An Explicit Phase-Behavior Model for Pseudocompositional Reservoir Simulation
Authors: Hustad O. S. , Dalen V. 
Published: June 2014

SUMMARY
An efficient phase behavior model for pseudocompositional reservoir simulation has been developed.1 The model is based on relatively few pseudocomponents and permits an explicit solution of the phase equilibrium problem. The model parameters are generated from a (simulated) laboratory experiment, that gives suitable compositional and volumetric data. A principal component analysis2 is performed on the compositions from the experiment for the selection of optimal pseudocomponents. The model has been implemented in a compositional reservoir simulator, and comparisons between results obtained with an equation of state approach and the proposed model indicate that the proposed model in many cases may be an attractive alternative to a full compositional treatment for cases where a black oil model is not representative.
Effective Relative Permeabilities for Viscously-Dominated Flow Through Cross-Bedded Units
Authors: Kasap Ekrem , Lake Larry W. 
Published: June 2014

ABSTRACT
The size of the local heterogeneity of most naturally-occurring permeable media is too small to be included in a numerical simulation. However, we can characterize the medium with prototype regularities in the heterogeneity and express the effects of these prototypes through effective relative permeability functions. Cross-bedded flow units, found mainly in sandstone reservoirs, are good candidates for this procedure.
This study describes an analytic method to generate effective relative permeabilities that account for the effects of heterogeneity on a miscible displacement in viscously dominated (gravity-free) flow. The method consists of discretizing a flow unit into subunits to which is assigned an effective permeability tensor that resolves cross bedding and cross-bed orientation. The effective permeability is, in general, a tensor that has nonzero off-diagonal elements. We then analytically generate effective (pseudo) relative permeabilities to account for vertical efficiency sweep caused by differences between the subunits.
We validate the proposed procedure with results that model permeability laminations explicitly on a very fine scale with a finite element simulator. The comparison indicates that analytically generated effective relative permeabilities can accurately account for small heterogeneities in numerical simulations. Thus, effective relative permeabilities, an immiscible flow concept, are used to represent heterogeneities in a miscible displacement. The procedure is limited, however, to viscously-dominated flow.
An Improved Viscosity Correlation for CO2/Reservoir Oil Systems
Authors: Lansangan R. M. , Taylor M. , Smith J. L. , Kovarik F. S. 
Published: June 2014

SUMMARY
This paper presents a correlation for predicting viscosities of CO2/-hydrocarbon mixtures. Viscosities were measured with a piezoelectric quartz crystal over a range of conditions from 32.2°C [90°F] to 121.1°C [250°F] and 6.89 MPa [1000 psi] to 34.5 MPa [5000 psi]. Crude oils and several synthetic oils were used in the study. The Lohrenz, Bray, and Clark (LBC) correlation was modified using the Corresponding States Principle coupled with new mixing rules to include mixtures with CO2 concentrations of up to 98 mole%. The new correlation showed about 70% improvement in average absolute deviation compared to the LBC procedure. The new correlation is expected to improve our capability to predict oil recovery performance both in the laboratory and in the field.
A Comprehensive Approach to In-Situ Combustion Modeling
Authors: Belgrave J. D. M. , Moore R. G. , Ursenbach M. G. , Bennion D. W. 
Published: June 2014

ABSTRACT
Low temperature oxidation (LTO) has long been recognized as one of the dominant mechanisms controlling fuel availability in in-situ combustion. Its effect on the physical properties of crude oils is also well known. In spite of these findings, the prevailing conceptual model of in-situ combustion still hinges on thermal cracking (in isolation) ahead of the firefront, to provide sufficient fuel (coke) for propagation of the reaction zone. Previous simulation studies, which purported to include LTO as part of the reaction scheme, have unrealistically specified the reaction products as carbon oxides and water. Furthermore, oil compositional changes due to oxidation have been completely neglected.
This paper describes a unified pseudo-mechanistic reaction model for mathematical modeling of in-situ combustion of Athabasca bitumen. The model represents a consolidation of individual experimental kinetic studies on thermal cracking and low temperature oxidation of Athabasca bitumen, and reported data for the high temperature oxidation of coke. The formulation is comprehensive in that it allows bitumen to undergo density and viscosity increases, as well as reduced reactivity to oxidation, with increased oxidation extent. Hydrocarbon bypassing due to quenching of the combustion front is also permitted with the proposed kinetic model.
The paper includes application of the reaction model in numerical simulations of adiabatic combustion tube tests performed on Athabasca bitumen. A significant feature of the model is its ability to predict the dual oxidation uptake peaks associated with ramped temperature oxidation experiments.
Effect of Rock type and Brine Composition on Adsorption of Two Foam-Forming Surfactants
Authors: Mannhardt Karin , Schramm L. L. , Novosad J. J. 
Published: June 2014

SUMMARY
Adsorption levels of two surfactants (anionic and amphoteric) suitable for foam flooding in high-salinity and high-hardness conditions were measured on sandstone and limestone with different brines. The anionic surfactant adsorbed more strongly on limestone than on sandstone, while the opposite behavior was observed with the amphoteric surfactant. The presence of divalent ions increased adsorption levels of both surfactants on both rocks. Adsorption mechanisms are suggested from measured surface charge properties of the rocks.
Effect of Drying on Travis Peak Cores Containing Fibrous lllite
Authors: Luffel D. L. , Herrington K. L. , Walls J. D. 
Published: June 2014

Summary
We conducted a laboratory study in the east Texas Travis Peak sandstone, which contains a small but significant amount of fibrous illite, to determine properties of preserved cores compared with those of dried and resaturated cores. Results showed that the drying process significantly changed effective water permeability, capillary pressure behavior, and electrical properties but that effective gas permeability as a function of water saturation did not change.
Experimental Micro-modeling and Numerical Simulation of Gas/Water Injection/Withdrawal Cycles as Applied to Underground Gas Storage Reservoir
Authors: Billiotte J. , de Moegen H. , Oren P. E. 
Published: June 2014

SUMMARY
This paper presents the results of an experimental and theoretical study of mechanisms responsible for the evolution and structure of the gas bubble during air-water injection-withdrawal cycles in 2D glass micromodels. Wetting films located in the corners of throat section conduct flow. Wetting film flow generates gas loop structure which increases injection efficiency and also the amount of trapped gas during withdrawal. During the next injection, blob distribution and wetting film flow induce a quicker breakthrough. Using a network simulator which takes into account wetting film flow, the influence of flow-rate on cycling is highlighted
Investigation of Crude-Oil/Mineral Interactions: Factors Influencing Wettability Alteration
Authors: Wolcott J. M. , Groves F. R. , Trujillo D. E. , Lee H. G. 
Published: June 2014

SUMMARYThe influences of core-pretreatment, brine saturation, and CO2-flooding on wettability alteration, and the site, nature and extent of organic deposition in Berea sandstone cores were investigated. Core samples were evaluated using the Amott method for wettability determination, pyrolysis, thin-section microscopy, and scanning electron microscopy (SEM). Investigations showed that CO2-flooding, KOH-treatment, and the presence of brine influenced wettability and the extent of organic deposition; however, there was little correlation between the degree of wettability alteration and the extent of organic deposition.
Scale Problems in Namorado Field
Authors: de Almeida Armando Ferreira , Ferreira Deise Massulo , Tavares Antônio Fernando Cabral , Bezerra Maria Carmen Moreira , Khalil Carlos N. 
Published: June 2014

ABSTRACT
Namorado field was discovered in November, 1975, and is located in the Campos Basin (Brazil) at about 80 kilometers from the sea-shore, in a water depth that varies from 130 to 240 m. The main reservoir is the Namorado Sandstone 1 with an original oil-in-place of 100 MM m3 (630 MMSTB).
The production was started in June, 1979, and the reservoir showed, initially, a great pressure decline caused by the absence of natural mechanisms of pressure maintainance. In order to maintain the reservoir pressure (energy) and obtain the maximum oil recovery, a sea water injection was started in May, 1984.
Today the field is producing around 7600 m3/d (48,000 BPD) with a recovery efficiency higher than 20%. A final recovery factor of 40% is expected to be reached with the water injection.
The water injection project has shown to be very efficient until now and the pressure has been stabilized around the bubble point pressure since the beggining of the injection. As a result of incompatibilities between the formation water and sea water, several wells have presented production problems caused by scale formation, mainly barium sulfate and strontium sulfate.
This paper presents the several problems caused by scale formation and gives an overview of what has been done to find a definitive and economically viable solution. This experience will help solving similar problems that may appear in other fields.
Numerical Simulation of Two-Phase Flow Using Locally Refined Grids in Three Space Dimensions
Authors: Mulder W. A. , Meyling R. H. J. Gmelig 
Published: June 2014

SUMMARY
A numerical method for incompressible, immiscible, two-phase flow is presented, that uses dynamic local grid refinement and operator splitting. Elliptic equations are solved by a multigrid method, hyperbolic equations by a nonlinear characteristic method. Large time steps are permitted and high accuracy and efficiency are obtained if the total flow field does not strongly depend on the saturation distribution.
Analysis of a Hydraulically Fractured, Low Permeability Gas Reservoir Using Numerical Simulation
Authors: Bastian Peter A. , Sherman Jan B. 
Published: June 2014

ABSTRACTWe have used a three-dimensional, multi-phase reservoir model to history match the post-fracture performance data of two separate completions in the complex, low permeability Travis Peak formation. This model consists of a two-layer, two-phase (gas-water) reservoir in communication with the wellbore via a vertical hydraulic fracture. The two-layer, two-phase reservoir model accurately matches post-fracture production data and pressure buildup test data from each Travis Peak completion interval.Our results show that the properties of the hydraulic fractures determined by this reservoir simulation are in good agreement with the fracture properties determined by a three-dimensional (3-D) fracture propagation model. In addition, reservoir simulation history matching determined that a multi-layer reservoir system was necessary to model the performance in the lower Travis Peak completion interval.