bluuebunny/crossref_metadata_2025_split huggingface dataset:
History Matching of a North Sea Flowline Startup
Authors: Burke N.E. , Kashou S.F. , Hawker P.C. 
Published: December 2007

Summary
This paper presents a history match of the startup conditions measured for a buried offshore North Sea oil flowline. Wellhead and platform-arrival temperatures, pressures, and flow rates were predicted as the production rate varied during startup. The simulation study was performed with the new workstation version of OLGA® (Version 1.4), a transient and steady-state multiphase-fluid-flow simulator. The OLGA simulator rigorously models the transient hydraulic and heat-transfer effects that occur during flowline startup. The effects of surface production devices, such as variable area chokes, were included in this study. Results from steady-state and transient runs are compared with field data. Good agreement was obtained between field and predicted values. This study also illustrates the importance of the phase behavior of the oil, fluid properties, and heat transfer on the simulation performance. Simulated steady-state results compared favorably with results predicted by PIPEPHASE®, a steady-state multiphase-flow simulator.

Introduction
There is an increasing need to develop more oil and gas fields in harsh offshore environments. The special problems associated with offshore operations pose new challenges in the design and development of economical offshore production systems. Problems specific to the offshore environment include hydrates, wax deposition, and transient slugging. In an offshore cold-water environment, the transient effects during production system startup and shutdown become more pronounced. New transient simulation tools, such as OLGA, are becoming available that aid in the design and modeling of these transient effects. OLGA also can be used to predict the slugging and depressurization behavior of the flowline system to aid in the design of topside facilities.
This study uses the OLGA transient multiphase-flow simulator to history match actual startup data from a North Sea field. The transient data matched included mass flow rate, platform temperature and pressure, and wellhead temperature and pressure. This type of data study is useful for designing treatment and prevention programs for hydrate and wax deposition in offshore flowlines.
Case History: Design, Implementation, and Results of Separator Retrofits
Authors: Broussard G.C. , Meldrum Neil , Choi M.S. 
Published: December 2007

Summary
Dubai Petroleum Co. (DPC) performed two in-situ offshore separator retrofit projects during 1989-91. Significant cost savings were achieved over the alternatives of separator replacement, addition, or modification onshore. The retrofits were accomplished without production loss or compromised operating safety. DPC's experience demonstrates that in-situ offshore facility modifications can be done successfully and simultaneously with normal operations. Improved performance after the retrofits strongly supports the need for properly designed internals to realize the full potential of a separator. Although the two retrofits share a common objective, they differ significantly in design, planning, and execution. First, a three-phase separator critical for uninterrupted production was modified during a 6-day scheduled fieldwide shutdown using only "cold work." This was followed by the conversion of a two-phase, double-barrel separator to three-phase service without a field shutdown. The work took place during 6 months with the use of "hot work." The success of both field modifications was attributed to innovative engineering and careful planning.

Introduction
Production is gathered from 67 platforms offshore Dubai, through a network of subsea multiphase pipelines to the central facilities at Fateh and S.W. Fateh (Fig. 1). Gas is separated and compressed for gas lift and pipeline export. Water is removed, processed, and disposed overboard. Separated oil from the S.W. Fateh central facilities is pumped to Fateh for further stabilization, dehydration, storage, and tanker offtake in three "khazzans." Khazzans are large, openbottom, underwater storage containers that resemble inverted champagne glasses. The oil floats on top of the water within the khazzans and displaces seawater out the bottom as more oil is introduced. During the 6 or more hours that the oil resides in the khazzans, its basic sediment and water (BS&W) is reduced to less than 0.5% for tanker sale.
Before 1987, all production separators in the system operated in the two-phase mode. They removed the gas from the produced fluid before it was sent to the khazzans. Oil and water separation took place entirely in the khazzans. This method of water separation and disposal was abandoned for three-phase separation when water production increased to levels that exceeded the capacity of the khazzans.
Description and Analysis of Cored Hydraulic Fractures—Lost Hills Field, Kern County, California
Authors: Fast R. E. , Murer A. S. , Timmer R. S. 
Published: December 2007

Summary
An inclined observation well was drilled in shallow (2,000 ft) Opal-A diatomite. Seven sand-propped hydraulic fractures were cored and recovered. The hydraulic fractures were found within 5° of the azimuth measured with tiltmeters and were tilted 15° from vertical, oriented perpendicular to the formation bedding dip. Hydraulic fracture widths ranged from less than one sand grain (40/60 mesh) to 0.4 in. Scanning electron microscopy (SEM) examination of fracture faces showed no damage to the matrix from proppant embedment or compaction, and no evidence of guar residue was detected in the proppant pack or on the formation face. Fractures appear to be considerably longer than modeled. Three closely spaced fractures are interpreted to be branches of a single hydraulic fracture treatment. This paper presents a description of the fractures recovered during coring in Well OO2. Findings related to fracture dimensions and orientations, fracture sources, fracture permeability measurements, and fracture characteristics (proppant embedment, presence of gel residue) are presented. Implications related to field development are discussed.
Fracture-Liquid Transmissibility in Fractured Porous Media
Authors: Firoozabadi Abbas , Markeset Tore 
Published: December 2007

Summary
The flow of oil phase in the gas/oil two-phase region in fractures is a key to production performance of fractured petroleum reservoirs where gravity drainage is the dominant mechanism. In this study, data on a set of experiments that center on flow of the oil phase in the fractures are presented. The experiments cover fracture apertures ranging from 50 to 1,200 µm, and the contact area is varied by a factor of 16. The data reveal that the rate of oil drainage across a stack of matrix blocks is very sensitive to fracture aperture size.
Borehole Stability in Shales
Authors: Bol G. M. , Wong S-W. , Davidson C. J. , Woodland D. C. 
Published: December 2007

Summary
Downhole mud/shale interaction can only be properly understood if rock mechanical, shale hydration, and fluid transport phenomena are taken into account. This paper presents a review of Koninklijke Shell E&P Laboratorium's research on borehole stability in shales. Mechanisms relevant to shale stability, including pore pressure penetration (the gradual increase in pore pressure resulting from high mud weight), capillary threshold pressures, compressive and tensile failure, postfailure stabilization, hydration stress, inhibition, and osmotic phenomena are discussed. We attempt to integrate these mechanisms into a comprehensive model for shale behavior.
Calculation of Voidage for Water Injection Fillup Requirements in a Reservoir Without Initial Gas Cap When Past Production Data Are Available
Authors: Earlougher R.C. , Turner W.J. 
Published: December 2007

Data required:Symbol Cumulative oil production, STB Np
Cumulative gas production, Mcf Gp
Cumulative water production, bbl Wp
Original formation volume factor Boi
Formation volume factor at zeroreservoir pressure and atreservoir temperature Boa
Original solution GOR Rsi
Cumulative water injection, bbl Wi
Desired:
Gross liquid voidage from the reservoir, in barrels, resulting from production of oil, gas, and water. This value represents the volume of net waterinjection required to fill the reservoir with liquidand thus regain initial bottom-hole pressure. Whenthat condition has been fulfilled, "fillup" will havebeen attained.
Vt = cumulative gross voidage, bbl
Vtn = cumulative net voidage, bbl
Vt = current gross voidage, B/D
Vtn = current net voidage, B/D
Fillup = Vt at start of water injection
Solution:
Vt =
Vtn =
Vt =
where
Vt2 = cumulative gross voidage at end ofmonth,
Vt1 = cumulative voidage at end of previousmonth, and
d = days in the month.
Vt =
This calculation assumes that all free gas in the reservoir will go back into solution as reservoir pressure is increased by injection. Field performance pressure is increased by injection. Field performance of waterfloods confirms this assumption. Average reservoir pressure will increase relatively slowly up to 50 to 80 percent of fillup and then build up rapidly.
P. 931
Annular Re-injection of Drilling Wastes
Authors: Minton R.C. , Secoy Byron 
Published: December 2007

Summary
Annular reinjection offers a cost-effective disposal mechanism for the oily cuttings and associated wastes generated when oil-based muds are used during drilling. This disposal method eliminates overboard cuttings discharge and hence removes any environmental impact. Continued use of oil-based muds is therefore feasible. A 12-member Drilling Engineering Assn. in Europe (DEAE) project was initiated in 1990 to study the engineering aspects of this approach in the North Sea. This paper reports on the first trial off a fixed platform in the North Sea and discusses the preliminary engineering studies, injection, and analysis of fracture propagation. It demonstrates that, with proper regard to the engineering of the injection well, the process is a safe, efficient, and effective disposal technique.

Introduction
Low-toxicity oil-based muds (LTOBM's), used widely in the North Sea operating area, offer significant operational benefits, especially for exploration and appraisal drilling and, more importantly, for development drilling. However, the overboard discharge of the oil-contaminated cuttings leads to environmental damage that, although localized, is unacceptable.
To resolve this conundrum, novel water-based muds were evaluated and a range of cleaning and disposal options for the cuttings was reviewed. From these options, cuttings slurrying and reinjection appeared to offer the most cost-effective solution because this approach would also address the problem of oily liquids from the drilling unit. Cuttings slurrying and reinjection is established practice in Alaska and the Gulf of Mexico, but the technique had not been used previously in the North Sea.
We knew that the legislative authorities would have some concerns. Therefore, 12 operating companies sponsored a joint project, through the auspices of the DEAE, to evaluate the engineering issues associated with this approach. The project was established with three objectives in mind:to demonstrate that cuttings slurrying and reinjection was technically viable for the North Sea,to gain acceptance of this approach to waste management from North Sea legislative authorities, andto evaluate a novel approach to cuttings grinding.
A Transform Approach to the Simulation of Transient Gas Flow in Porous Media
Authors: Andre H. , Bennion D.W. 
Published: December 2007

Abstract
The mathematical description of transient gas flow through porous media leads to a second-order nonlinear partial differential equation for which no analytical solution bas been found. For flow in one linear dimension, this paper outlines a procedure for using finite Fourier transforms to reduce the partial differential equations to a set of first-order, partial differential equations to a set of first-order, nonlinear ordinary differential equations with time as the independent variable. The dependent variables of these equations are the Fourier transform coefficients of the gas pressure in the porous media The procedure is applied to an porous media The procedure is applied to an example problem and calculated results are compared with other published results obtained by a numerical finite-difference technique. The good agreement shown between the two sets of results tends to confirm the validity of both solutions.

Introduction
The differential equation describing one-dimensional gas flow in porous media is a nonlinear equation with no known analytical solution. Numerical finite-difference methods are normally used to solve the flow equation. This paper presents a method which uses linear analysis to transform a second-order problem into a set of first-order problems. Basically the approach used is to assume an approximation of the solution consisting of known functions and unknown parameters and apply some error distribution parameters and apply some error distribution principles to determine the parameters of the principles to determine the parameters of the approximation. Although there are several error distribution principles, one of the most common is the orthogonal method. Recently special cases of the orthogonal method, the Galerkin or Bubnov-Galerkin have been applied by Price et al., to petroleum reservoir problems with considerable success. A classical orthogonal method is finite Fourier transforms. Recently several authors have demonstrated that this method can be used with considerable success in the simulation of systems described by a limited class of linear partial differential equations. This paper is intended to demonstrate that the finite Fourier transform method can be used to reduce the nonlinear partial differential equation describing gas flow in a linear porous media to a set of ordinary differential equations.

THEORY
The basic equation being studied is:
............(1)
which is derived from the continuity equation
...............(2)
the equation of state
..............(3)
and Darcy's law
................(4)
For the orthogonal method of error distribution, the procedure is to assume an approximate solution Pa, define an error L[pa] and require that this error Pa, define an error L[pa] and require that this error be orthogonal to N independent functions n(x) (n=1,2.... N)
...................(5)
SPEJ
P. 135
Relation Between Chemistry and Flow Mechanics of Borate-Crosslinked Fracturing Fluids
Authors: Kruijf de A. S. , Roodhart L. P. , Davies D. R. 
Published: December 2007

Summary
Borate-crosslinked guar or hydroxypropyl guar (HPG) polymer solutions have become increasingly popular as hydraulic fracturing fluids. These fluids are cheap and environmentally friendly, and they minimally impair a propped fracture while yielding maximum viscosity. The drawbacks, which have limited their use, are a restricted temperature range of applicability, relatively high tubing friction, and poor stability when prepared with seawater. This paper shows how these drawbacks can be eliminated by a fundamental understanding of the relation between fluid chemistry (as a function of borate crosslinker, pH, and polymer/crosslinker concentration) and its physical properties (proppant-carrying capacity, viscoelasticity, and the temperature stability of the resulting crosslinked structure).
Interaction of Viscous Fingering, Permeability Heterogeneity, and Gravity Segregation in Three Dimensions
Authors: Tchelepi H. A. , Orr F. M. 
Published: December 2007

Summary
Two- and three-dimensional computations with a hybrid finite-difference/particle-tracking technique are compared for unstable displacements. In both homogeneous and heterogeneous porous media, gravity segregation is much more effective in 3D than in 2D computations. Whether flow is 2D or 3D, the presence of correlated heterogeneities lowers the range of viscous/gravity ratio over which the transition from gravity- to fingering-dominated flow occurs.
Comparison of 2D and 3D Fractal Distributions in Reservoir Simulations
Authors: Beier R. A. , Hardy H. H. 
Published: December 2007

Summary
Fractal geostatistics can be used to generate distributions of such reservoir properties as porosity and permeability. We compare three different methods that use these distributions in reservoir simulations. The first method is a hybrid finite-difference/stream-tube method that starts with 2D vertical cross sections with relatively fine grids, the second uses pseudo-relative permeabilities and also is based on 2D cross sections, and the third uses 3D distributions. A mature waterflood in a carbonate reservoir serves as a field test case.
Effect of Phase Behavior on Bypassing in Enriched Gasfloods
Authors: Burger J. E. , Bhogeswara Rao , Mohanty K. K. 
Published: December 2007

SummaryEnriched gasfloods incorporate a complex interaction of heterogeneity, fingering, multiphase flow, and phase behavior. Experiments and simulations indicate that the optimum solvent enrichment in high-viscosity-ratio secondary gasfloods can be below minimum miscibility enrichment (MME). The compositional path and resulting mobility profile in multidimensional multiple-contact miscible (MCM) or immiscible floods are different from their ID counterparts for high-viscosity-ratio floods in heterogeneous media.
The Impact of Wettability on Waterflooding: Pore-Scale Simulation
Authors: McDougall S. R. , Sorbie K. S. 
Published: December 2007

Summary
This paper describes the development and implementation of a pore-scale simulator into which pore-wettability effects have been incorporated. Relative permeability and capillary pressure curves from this steady-state model have been analyzed to allow better interpretation of experimental observations from a microscopic standpoint. The simulated capillary pressure data demonstrate that some standard wettability tests (such as Amott-Harvey and free imbibition) may give misleading results when the sample is fractionally wet in nature. Waterflood displacement efficiencies for a range of wettability conditions have been calculated, and recovery is shown to be maximum when the oil-wet pore fraction approaches 0.5. Furthermore, a novel experimental test is proposed that can be used to distinguish between fractionally wet and mixed-wet porous media. To date, no such satisfactory test exists.
A Comprehensive Model of Fluid Loss in Hydraulic Fracturing
Authors: Yi Tongchun , Peden J. M. 
Published: December 2007

SummaryThis paper presents a comprehensive model of the fluid-loss process that occurs in hydraulic fracturing. The model treats the three flow regions in the leakoff process—the filter cake, the invaded zone and the reservoir zone—as a composite system with a rigorous account of the interface between the last two zones. This allows automatic consideration of the variation in pressure drops across the three zones and the inclusion of many variable physical aspects in each region. For the description of the filter cake behavior, effects of the internal filter cake, core length, shear rate, and non-Newtonian behavior of fluids have been taken into account. In the invaded zone, the non-Newtonian behavior of the filtrate, the permeability damage caused by the filtrate invasion, and rock and fluid compressibility have been simulated. Different boundary conditions, such as no-flow, constant-pressure, finite, and infinite boundaries, have been incorporated into the model, making it applicable for simulating both laboratory tests and the real leakoff process in fracturing treatments under a variety of conditions.The model has been validated against laboratory and published data. Excellent agreement between predicted results and test data has been achieved. The analyses show that the non-Newtonian behavior of the filtrate represented by the model has a significant effect on leakoff. Leakoff would be considerably underestimated if a Newtonian fluid filtrate, as in the classic theory, were assumed instead of the non-Newtonian system. We also show that the variation in pressure drops across the three zones may cause a strong nonlinear relation between leakoff and t½ that cannot be explained by the classic theory because constant pressure drops are assumed.
A Multidisciplined Approach to Designing Targets for Horizontal Wells
Authors: Solomon S.T. , Ross K.C. , Burton R.C. , Wellborn J.E. 
Published: December 2007

Summary
A multidisciplined approach to developing 3D target diagrams and their associated tolerances provides a cost-effective method for designing horizontal wells. The key to this approach is that the diagram quantifies and communicates the uncertainty of the target boundary conditions to others involved in designing and drilling a well. Field examples show how a multidisciplined team creates a 3D target diagram. The preliminary 3D diagram is used to examine the combined uncertainty in the position of the features constraining the target. To maximize the target size, the team must decide on the relative importance of each constraining feature and assign target tolerance limits. The final target diagram minimizes both risk and cost to produce the optimum well design.

Introduction
With horizontal drilling equipment and technology improvements, efforts are now being directed toward optimizing the horizontal drilling process by lowering costs. Planning is widely acknowledged as the key to success in any horizontal drilling project; however, the importance of target design in well planning is not always as well recognized.
Targets for horizontal wells are by necessity 3D. Initially, this concept was a challenge to an industry more familiar with using 2D geometric figures to design vertical or conventional directional well targets. For the first horizontal wells, the simple 2D geometric target shape became a 3D "box." Drilling engineers discovered that these simplistic well targets were inadequate and caused severe problems during drilling be cause they fail to address geological and reservoir uncertainties. Targets were often missed entirely when the formation top of a thin zone "came in" too high or too low. Drilling personnel discovered very quickly how inefficient and expensive it was to "chase" a horizontal target that dipped away. Experiences like these prompted interdisciplinary discussion. Drilling engineers sought to become more informed on the geological aspects of the horizontal prospect. In response, geoscientists found that they needed more information on the horizontal drilling process. It was soon (re)discovered that a well's success was directly related to the amount and quality of information shared among the different people responsible for the drilling project. It was also found that this information and its reliability could be communicated best through pictures by a 3D well target diagram.
This paper discusses the multidisciplined process of designing 3D horizontal well diagrams and provides field examples of their use. The importance of communicating the uncertainty of each target constraint between disciplines is emphasized as the key to cost-effective target design.