bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymer Adsorption/Retention in Porous Media: Effects of Core Wettability and Residual Oil
Authors: Broseta D. , Medjahed F. , Lecourtier J. , Robin M. 
Published: June 2014

ABSTRACT
Low polymer retention in the reservoir is essential to the success of a polymer EOR operation. It is usually estimated from laboratory core flood experiments conducted under conditions as close as possible to those prevailing in the field. This paper addresses the effects of core wettability and oil saturation on polymer adsorption/retention.
Adsorption of EOR water-soluble polymers onto oil or, more generally, hydrophobic substrates was estimated from a series of core flood experiments on alkane-coated (silane-treated) substrates and compared to adsorption on the bare siliceous substrates. A significant adsorption onto hydrophobic surfaces was found, the effect being stronger for nonionic Polyacrylamide and polysaccharides (scleroglucan and xanthan) than for anionic (hydrolyzed) Polyacrylamides.
In a second series of core flood experiments, Polyacrylamide adsorption/retention in cores under residual oil saturation was measured and compared to the adsorption/retention in similar oil-free, 100% brine saturated, cores. In oil-wet cores, retention decreased considerably in the presence of oil, while it increased slightly in water-wet systems.
These effects may be explained in terms of water/rock and water/oil interfacial area distribution within the pore space, which is governed by wettability. In water-wet cores, droplets of residual oil offer an additional adsorbing surface to the polymer, whereas in oil-wet cores the oil wetting film offers the polymer an adsorbing surface much smaller than the (no longer accessible) rock surface.
Applying Fractional-Flow Theory to Foam Processes at the "Limiting Capillary Pressure"
Authors: Zhou Z. H. , Rossen W. R. 
Published: June 2014

SUMMARYA fractional-flow analysis is extrapolated from laboratory data for foams at the "limiting capillary pressure." This analysis suggests that for continuous-injection foam processes, the best surfactant should drive water saturation to the lowest possible value and be sensitive to permeability. For WAG processes, the best surfactant should cause foam to degrade over a range of water saturations.
Effect of Conductivity on Horizontal-Well Pressure-Behavior
Authors: Ozkan E. , Sarica C. , Haciislamoglu M. , Raghavan R. 
Published: June 2014

SUMMARYThis study investigates the effect of pressure drop within the horizontal section on horizontal-well responses. A general, semi-analytical model that couples wellbore and reservoir hydraulics is presented. Dimensionless groups are defined to correlate the effect of wellbore hydraulics on horizontal-well responses. Flux and pressure distributions along the length of the well are investigated and the validity of the infinite-conductivity assumption is discussed. Short- and long-term characteristics of pressure responses along with asymptotic expressions are documented.
Interpretation of Oil-Water Relative Permeabilities from Centrifuge Experiments
Authors: Hirasaki G. J. , Rohan J. A. , Dudley J. W. 
Published: June 2014

ABSTRACTCollection of production data from centrifuge displacement with a time resolution of seconds and volume resolution of 4 µl provides the precision for interpreting the transient data for the displaced phase relative permeability curve. Interpretation for the relative permeability requires a simulation model that includes all relevant phenomena that affects the displacement. This includes the variation of the centrifugal force within the sample and during the centrifuge start-up period. Capillary pressure is a significant factor in both the initiation and cessation of production and thus must also be included in the analysis. The finite mobility of the invading phase places limitations on the portion of the relative permeability curve that is in the region of the shock. In addition, the finite mobility of the invading phase reduces the sensitivity to the initial (end ppinf) relative permeability of the displaced phase. The design of experiments in mixed wet systems require a balance between the Brownell-Katz (or Bond) number criteria for displacement of a disconnected phase and retention due to a capillary end effect.
Effect of Gas Enrichment and Dispersion on Nearly Miscible Displacements in Condensing/Vaporizing Drives
Authors: Johns R. T. , Fayers F. J. , Orr F. M. 
Published: June 2014

ABSTRACT
Compositional simulation and analytical solutions are presented that model enriched gas drive processes using only four pseudocomponents. A four-component model is used and compared to a more detailed 12-component model to examine the effects of dispersion, gas enrichment and pressure on oil recovery.
We show that a simple four-component lumping method can give a model with acceptable average front velocities that exhibits features of both condensing and vaporizing displacements. Furthermore, we show that a four-component model can achieve a nearly exact match to the 12-component model if the four-component enrichment level is adjusted. We also compare the dispersion-free analytical four-component solution with a dispersive four-component compositional simulation to demonstrate that dispersion causes some two-phase flow in a displacement that would otherwise be multicontact miscible (MCM). As dispersion increases in both the four and 12-component models, the oil recovery is reduced, especially near the minimum enrichment for miscibility (MME).
The Validation of Horizontal Well Models Using a Physical Model of Heat Flow in Anisotropic Conductor
Authors: Sabeh Michael A. , Enick Robert M. 
Published: June 2014

ABSTRACT
Two recently proposed models of fluid flow in anisotropic media yield different expressions for horizontal well productivity due to their representation of the wellbore. The model developed by Babu and Odeh used a point source/sink for the wellbore, while Peaceman's model implemented an isobaric boundary along the surface of the wellbore. Babu and Odeh's model predicted elliptical isobars, even in the immediate vicinity of the wellbore. Peaceman's model predicted a rapid transition from circular to elliptical isobars as the distance from the wellbore increased. Both models were mathematically correct and seemed plausible, but only one could have been accurate with respect to the actual system. Therefore the more appropriate model to use in reservoir simulation was determined experimentally.
The temperature-induced flow of heat from an anisotropic conductor into a circular heat sink is analogous to the pressure-induced flow of fluids from an anisotropic porous medium into a circular wellbore since the governing differential equations for both processes are identical in form. Heat transfer experiments were therefore used to model this fluid flow problem. The position and shape of isotherms in an anisotropic conductor corresponded to the position and shape of an isobar in a porous medium.
The results clearly indicated that a transition from circular to elliptical isopotentials occurred, in agreement with Peaceman's model. It is therefore more appropriate to model a wellbore as an isopotential of finite diameter when studying near-wellbore problems, such as the calculation of well productivity. If one desires to use the point representation, the modifications suggested by Brigham and Peaceman should be employed.
Component Partitioning in CO2/Crude Oil Systems: Effects of Oil Composition on CO2 Displacement Performance
Authors: Hagedorn K. D. , Orr F. M. 
Published: June 2014

Abstract
Gas chromatography/mass spectrometry (GC/MS) was used to analyze equilibrium phase samples from CO2/crude oil mixtures. K-values, or partitioning coefficients, are presented for over 250 individual components in these CO2/crude oil mixtures. The data show that both molecular size and structure affect the way a molecule partitions into a CO2-rich phase. Multi-ring aromatic compounds partition much less favorably into the CO2-rich phase than other components with similar molecular size or similar GC elution time.
Two crude oils which have similar carbon number distributions, but different slim tube displacement behavior, were analyzed by GC/MS. The oil containing a significant quantity of multi-ring aromatics produced a much lower slim tube recovery at given pressure, and had a correspondingly higher minimum miscibility pressure (MMP).
Equation of state (EOS) flash calculations and compositional simulations indicate that inclusion of the properties of the multi-ring aromatic compounds in an oil characterization is required if the types of behavior observed experimentally in both the single contact partitioning experiments and in slim tube experiments are to be reproduced numerically for oils containing significant quantities of multi-ring aromatic compounds.
The Transformational Decomposition (TD) Method for Compressible Fluid Flow Simulations
Authors: Moridis G. J. 
Published: June 2014

SUMMARY
A new method, the Transformational Decomposition (TD) method, is developed for the solution of the Partial Differential Equations (PDE's) of single-phase, compressible liquid flow through porous media. The major advantage of the TD method is that it eliminates the need for time discretization, and significantly reduces space discretization. There are two stages in the TD method: a Decomposition stage and a Reconstitution stage. In the Decomposition stage the original PDE is decomposed by using a Laplace transform for time, and successive levels of finite integral transforms for space. Each level of finite integral transform eliminates one active dimension, until a small set of algebraic equations remain. The original PDE is thus decomposed into much simpler algebraic equations, for which solutions are obtained in the transformed space. In the Reconstitution stage, solutions in space and time are obtained by applying succesive levels of inverse transforms. In contrast to traditional numerical techniques, the TD method requires no discretization of time and only a very coarse space discretization. The TD method is tested against results from one- and two-dimensional test cases obtained from a Finite Difference (FD) simulator, as well as from analytical models. The TD method may significantly reduce memory requirements because discretization in time is not needed, and a very coarse grid suffices for the space discretization. Execution times may be substantially reduced because smaller matrices are inverted and solutions are obtained at the desired points in space and time only.
Nuclear Magnetic Resonance Measurements of Wettability and Fluid Saturations in Chalk
Authors: Howard J. J. , Spinier E. A. 
Published: June 2014

SUMMARY
Laboratory Nuclear Magnetic Resonance (NMR) measurements on chalk cores are used for a rapid and accurate determination of fluid saturations and a qualitative estimate of wettability. Relaxation-time populations generated by a non-linear optimization technique clearly distinguish between the water and hydrocarbon phases in pores at various water-saturation states. Shifts of these relaxation time populations are interpreted as indicators of pore-wall wettability. These relaxation time shifts also correlate with changes in saturation exponents determined from resistivity measurements at initial water saturation, Swi. Quantitative estimates of water saturation in these predominantly water-wet chalks at both initial irreducible water and after spontaneous water imbibition are in excellent agreement with more conventional core analyses.
Scaling Fluid Flow Through Heterogeneous Permeable Media
Authors: Li Dachang , Lake Larry W. 
Published: June 2014

ABSTRACT
Despite several decades of study, there is no rigorous method for scaling flow through heterogeneous permeable media. Existing methods neglect heterogeneity and spatial correlation, which we now know to be of fundamental importance in many processes. On the basis of statistical techniques and inspectional analysis, we present a general method to scale flow through heterogeneous permeable media for an immiscible displacement of oil by water in a two-dimensional, anisotropic, heterogeneous cross section with statistically stationary properties.
Our results illustrate the interplay among local heterogeneity (the variance at a lower cutoff in a power-law variogram), global heterogeneity (the variance at an upper cutoff) and zonal heterogeneity (the power-law upper cutoff and exponent). The effects of the scaling groups obtained from the method have been examined in detail, and some important flow characteristics, which were unknown or poorly understood before, have been revealed.
Safety Management Systems: Questioning Some Fundamentals
Authors: KEARNS JOHN , SHARP LAN , TAYLOR DONALD 
Published: June 2014

1.0 Abstract
The Gullen Enquiry into the Piper Alpha disaster emphasised the importance of work practices as well as equipment hardware in ensuring safety offshore. In the complex offshore environment, the need to dovetail the various work practices and safety initiatives is paramount. The resulting integrated corpus is termed a Safety Management System (SMS). Many SMS concepts have been borrowed from the related discipline of Quality Management. Sometimes these concepts are used without thought as to what specific benefits they bring to safety.
The authors believe that the industry is beginning to loose sight of utility when putting in place certain elements of SMS. Some work practices and initiatives are instigated because they are expected to be there rather than because of need. In three specific areas, BHP Petroleum has developed novel elements of their Safety Management System for North Sea Production operations in order to satisfy specific needs.
The first element is Safety Auditing. BHP has developed a custom designed auditing system which focuses on the offshore installation rather than the overall Safety Management System. This auditing system takes as its point of departure the specific hazards that exist on the installation in question.
The second element relates to safety responsibilities. In defining safety responsibilities, it is very easy to give individual members of the workforce too much direction. The result can be an overly proceduralised and rigid organisation. BHP are in the process of developing a system for delineating safety responsibilities in order to support training goals. This allows members of the workforce scope to apply good judgement in a goal setting way.
The third element concerns the management of safety in contractors operations. Rather than requiring a contractor to import the Operators SMS, BHP has developed a mechanism for using and enhancing the Contractors existing Safety Management System.
This paper provides a description of how these systems work.
A Model for the Production Interference of Multiple Reservoirs Sharing a Common Aquifer
Authors: Rodriguez F. , Samaniego-V F. , Cinco-Ley H. 
Published: June 2014

Abstract
A semi-analytical model for the production interference of multiple reservoirs sharing a common aquifer is presented in this work. A two dimensional finite aquifer is considered, with nr reservoirs located across the aquifer domain. Water injection is allowed through nw arbitrarily located injection wells. The solution to this problem provides the pressure distribution in the aquifer and the average pressure and water influx for each of the reservoirs, as a function of time.
The flow behavior in a given aquifer-reservoirs system was found to be governed by the hydraulic diffusivity of the aquifer, ηα, the pore volume-total compressibility of the aquifer, (Vpct)a, and of the reservoirs, (Vpct)r, r = 1,2,…,nr the aquifer dimensions, xe,ye, and the location of the reservoirs within the aquifer. These parameters can be estimated through the model by history matching the average pressure of the reservoirs; the estimation of the water influx in each reservoir is obtained through the matching process.
A field application of the model is presented, which consists of the characterization of a system of three naturally fractured reservoirs sharing a common aquifer in the Gulf of México. Parameters estimated through the model were found most valuable as input data for numerical reservoir simulation of the system.
A Horizontal Well in a Depleted Reservoir in Lake Maracaibo: A Case Study
Authors: Suarez Tony 
Published: June 2014

Summary
This paper describes an integrated reservoir study performed to select a location for Maraven's first horizontal well in Lake Maracaibo, Venezuela. A depleted reservoir producing for 40 years, and with over 80 % of its recoverable book reserves produced, was selected to place the horizontal drainhole. The field has been yielding high water cuts since 1975, ranging from 85 to 95 %, and vertical new wells would water out within weeks. The reservoir study used a synergetic approach from a team composed of Petrophysicists, Geologists, Sedimentologists and reservoir engineers, from both the operator and the service company, aimed at choosing the reservoir and the best location within it. The selected reservoir has a dip of 30 degrees and leans against one of the major faults defined in the Lake Maracaibo basin.
Field Cases for Permeability Determination from Minifracs
Authors: Mayerhofer M. J. , Economides M. J. 
Published: June 2014

Abstract
The estimation of the reservoir permeability, a variable of great importance in hydraulic fracture design, is frequently inaccessible because candidate wells either do not flow or a pretreatment pressure transient test would be inordinately long (and expensive). A methodology for the interpretation of a fracture calibration treatment has been developed that allows the calculation of the permeability in addition to the traditional results of the "leakoff coefficient", closure pressure and fluid efficiency. Here, gas reservoir field cases are presented and interpreted with this method. A log-log diagnostic plot of the rate-normalized pressure and its derivative was employed to account for a multi-rate injection (fluid leakoff) and it is used to identify the transient reservoir response during fracture closing. The reservoir permeability can then be estimated from a specialized plot. This procedure is verified by a pressure match.
Transport Phenomena in Chemical Flooding
Authors: Porcelli P. C. , Bidner M. S. 
Published: June 2014

Abstract
A chemical flood simulator of a three-component, two phase system has been extended to include concentration dependent functions: phase behavior, relative permeabilities, capillary pressure, interfacial tension, residual saturations, phase viscosities, wettability, etc.. Their influence on concentration profiles and on oil recovery is analyzed hereupon.
Enhanced Oil Recovery by Means of Microorganisms: Pilot Test
Authors: Buciak J. , Vazquez A. , Frydman R. , Mediavilla J. , Bryant Rebecca 
Published: June 2014

Abstract
The paper presents the design, implementation and results of a microbial single-well stimulation test performed at the Diadema field in Argentina. The purpose of the test was to achieve increased production by injecting a microbial formulation and nutrients, and to gain experience with this procedure under actual field conditions. Two out of five treated wells showed excellent oil production response to the microbial stimulation.
The results suggest that a microbial-enhanced waterflood could be implemented successfully at the Diadema field.
Impact of Asphaltene Presence in Some Rock Properties
Authors: de Pedroza T. M. , Calderon G. , Rico A. 
Published: June 2014

Abstract
Several studies have shown that asphaltene precipitation at porous medium level leads to changes in some of its properties, such as wettability and hydraulic conductivity. This work shows the results obtained in a study aimed at assessing the effect of asphaltenes and its occasional precipitation on wettability and permeability of rocks found in Venezuelan oil reservoirs. Fluids and cores from five crude reservoirs having different asphaltene contents and Berea cores plugs were used. Wettability measurements were performed by using a variation of Amott method. Similarly, measurements were effected on cores in which precipitation was induced by n-pentane injection. Permeability reduction was evaluated by carrying out displacements tests before and after the precipitation induction.
All cases indicated the presence of changes in wettability. Such changes depend on the specific crude asphaltene content and always tend to an intermediate or preferential oil wettability condition, which does not increase during asphaltene precipitation.
Mean hydraulic radius reductions in tests where the precipitation was induced were in the range of 93.3 – 47%, which corresponded to asphaltene retention values of 19 and 3.6 %PV, respectively. These reductions depend on the rock nature and the core properties: permeability, porosity and pore size distribution.
Effects on the Marine Environment of Produced Formation Water Discharges from Offshore Development in Bass Strait, Australia
Authors: Terrens G. W. , Tait R. D. 
Published: June 2014

Abstract
An environmental effects study was undertaken to assess the potential environmental effects of discharged produced formation water from offshore oil and gas platforms in Bass Strait, Australia. The focus was on potential effects on the fisheries of Bass Strait. Produced formation water discharged to the ocean from the Halibut platform, one of the largest Australian oil fields and now the most prolific produced formation water field, was modelled for dilution versus distance from the platform. Characterisation of produced formation water from 10 Bass Strait platforms for chemical constituents and toxicity to local marine organisms was performed.
It was found that produced formation water discharged into Bass Strait presents a very low risk to marine organisms due to very low toxicity and very high dilution rates. For the Halibut platform, acceptable acute toxicity concentration of produced formation water can be obtained with dilution of less than 2:1. Actual dilution rates are approximately 30:1 within 10m of the discharge point, and concentrations reach an indicative "no chronic" toxicity effect level within 25m of the discharge point. The discharge plume is also spatially limited and mobile and any organism would be exposed to potentially lethal concentrations of produced formation water for the order of less than 30 seconds for median current conditions.
Remediation of Ponds and Landfills at a Gas Plant in Alberta
Authors: Kent R. P. , Beresford C. R. 
Published: June 2014

Abstract
Work is in progress on the remediation of contaminated ponds and landfills at a gas plant in central Alberta. Previous experience in the excavation and disposal of large quantities of heterogeneous, contaminated industrial wastes is limited. Through studies, investigations and pilot work a cost effective strategy for remediation has been developed.