bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Findings From Over Pressure Detection Curves In Tectonically Stressed Beds
Authors: Harper Douglas 
Published: December 2007

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
During the last few years, much work has been done on over pressure detection and predictions. predictions. The established rules have been applied, and are reliable in the Delta Country of South Louisiana and Nigeria. In these locales the beds are relatively flat or tectonically relaxed.
Some recent work has been done, utilizing shale densities and drilling data "d" Exponent over a large area that has been tectonically stressed. These areas of concern are the formations around the Andes of South America, the Coastal Regions of California, and Alaska.
The findings of this work seem to bear out the fact that the same rules apply in the tectonically stressed beds as would apply in the relaxed beds of the Delta Country. The big difference is in interpretation of the resulting curves.
In almost all cases in which over pressure could have been predicted prior to drilling, it was best to have at least two curves. These curves may not, in tectonically stressed beds, give the same slope change.
One may trend one direction and the other trend completely reverse. In cases where this has been observed, the fact that the curves changed is the important thing.
The curves have been used in the past on different occasions to predict over pressures, which allows proper pipe setting depth, and to solve problems of hole drag when formation pressure was near hydrostatic or trip pressure. pressure was near hydrostatic or trip pressure. It has been noted on several occasions that abrupt changes in a trend causes concern among the rig crews. This in turn has made them watch pit levels more closely and catch small "kicks" rather than large ones.

Introduction
The Drilling Industry dreamed for years of a way to predict over pressures. This would permit the people involved in drilling a remote "wild cat"' well to determine transition zones while the well is in progress.
Over pressure predictions were made in the past by Electric Logs and by other data compiled from what was termed, Similar Wells. Such practices resulted in wells being drilled with excessive mud weights, and subsequent loss of circulation by induced fracturing.
Miscible or Near-Miscible Gas Injection, Which is Better?
Authors: Thomas F. B. , Holowach Nancy , Zhou XueLong , Bennion D. B. , Bennion D. W. 
Published: December 2007

Abstract
Miscible flooding was invented many years ago, and in the 1950's it was viewed as one of the most promising techniques to use for improving oil recovery from a reservoir.1,2,3,4,5,6,7 Since that time many groups have researched what would be the most important parameters to optimize in the lab, have developed theoretical models to correlate these parameters, and then have implemented these "optimally designed" gas injection systems in the field. Amidst all the increase in technology and sophistication there is still ongoing debate as to whether one needs to achieve miscibility in order to optimize the recovery or whether a degree of immiscibility, characterized by the name "near miscible", is equally adequate for field implementation in enhanced oil recovery processes.
This paper seeks to provide insight into these questions by reviewing some of the parameters which are at work in gas injection EOR as well as qualifying some of the techniques which can be used in designing gases for injection. Moreover, case histories are described herein where laboratory work was performed, phase behavior described, and then the gas injected into the reservoir. Results from the field are then shown and commentary included on the field performance.
An Evaluation of Oil Recovery by Vaporisation
Authors: Espie A. A. , Brown C. E. , Merrill R. C. , Newley T. M. J. 
Published: December 2007

Abstract
Injection of lean gas into volatile oil reservoirs to recover oil by vaporisation is frequently identified as an attractive development option. This mechanism is a significant feature in reservoirs with large-scale gas recycling projects.
A fundamental evaluation of the process has been undertaken for a specific reservoir application to validate our understanding of the physical mechanisms. The local contact efficiency on a microscopic scale and the rescaling of data from the laboratory scale to simulator grid block scale were identified as areas of significant uncertainty.
In this study, accurate measurements of the local contact efficiency for a lean gas stream vaporising residual oil from a gravity drainage process have been made. The experiments were conducted at reservoir conditions using core from the Prudhoe Bay reservoir.
Use of the experimental measurements to validate a field scale model capable of process optimisation requires a number of steps. Firstly, a detailed simulation analysis of the core scale displacement is required to validate the model of the physical process on the microscopic scale. Then, as model length scales increase the effects of heterogeneity become increasingly important. The outstanding steps in the validation procedure are outlined.
Experimental Measurement and Modelling of Transition Zone Fluids
Authors: Nighswander J. A. , Chang-Yen D. A. , Perez Jorge , Kalra Harish 
Published: December 2007

Abstract
Current practice in the evaluation of suitable EOR solvents involves performing a number of slim tube displacement experiments. The information obtained from these tests is generally sufficient for the determination of minimum miscibility pressure (MMP) or minimum miscibility composition (MMC). However, in a standard slim tube displacement test, it is not possible to obtain quantitative information with regard to the phase behaviour of the transition zone fluids. This information is crucial for the development and tuning of compositional reservoir models used for simulating miscible displacement processes. Presently, this information is obtained from static fluid property tests such as P-х (swelling) or Benham multiple contact tests.
In this work, new experimental data for live transition zone fluid properties and compositions generated during a multi-component hydrocarbon displacement process are presented.
In addition, the experimental transition zone fluid properties have been predicted using an equation of state (EOS) model based on a fluid characterization obtained by matching P-х data. Results of these calculations indicate that it is not possible to predict transition zone fluid behaviour for the system under consideration using an EOS characterization based only on P-х data.
Minimum Miscibility Pressure, Rising Bubble Apparatus, and Phase Behavior
Authors: Mihcakan Metin , Poettmann F. H. 
Published: December 2007

Abstract
The objective of this study was to determine the minimum miscibility pressure (MMP) as a function of temperature using the rising bubble apparatus for a ternary system consisting of CO2, normal pentane, and normal hexadecane. The MMP's were compared and interpreted with the phase behavior of the ternary system. In addition, the MMP was determined for a dead oil of 41.7° API gravity and a live oil having a bubble point pressure of 2266 psia at a reservoir temperature of 240°F for CO2 and CO2 enriched with normal butane.
The MMP's as a function of temperature were determined using a modified rising bubble apparatus (RBA). Bubble behavior was monitored using a motion tracking optical system (MTOS) and a cell pressure data acquisition and monitoring system (CPMS). The MTOS consists of a video camera mounted on a rail table parallel to the path of the rising bubble in the sight gauge (or cell). The magnified bubble image is monitored on a screen and recorded on a video cassette for subsequent viewing. The VCR can playback the recorded image frame-by-frame or at any desired speed for detailed study of bubble behavior and shape. An image processor installed on the computer captures and digitizes selected bubble images that are printed out on a laser printer with high resolution. The CPMS records the pressure behavior in the cell as a function of time as the bubble rises in the oil column and aids in the determination of the MMP.
The MMP measured with the RBA for the ternary system agreed with the MMP as determined from the phase behavior of the ternary system. For the dead oil and the ternary system the MMP measured as a function of temperature terminates at a low temperature at the critical temperature and pressure of the injected gas for both the vaporizing and condensing systems. For the ternary system the MMP as a function of temperature for an enriched gas goes from a multiple contact condensing system to a multiple contact vaporizing system at the temperature where the enriched gas ternary system MMP curve crosses the CO2 -Ternary System MMP curve. At the cross-over temperature and pressure both the liquid composition and the enriched gas composition lie on the termini of the limiting tie line of the ternary system and thus the enriched gas is single contact miscible with the liquid.
A Polymer Thermal Decomposition Model and its Application in Chemical EOR Process Simulation
Authors: Lange E. A. , Huh Chun 
Published: December 2007

Abstract
Accurate assessment of the potential of high temperature chemical flood processes utilizing biopolymers for mobility control requires not only a model of polymer rheology and retention but also a model of polymer thermal decomposition. A detailed model for the thermal decomposition of a polymer flowing in a high-temperature reservoir was developed for use in simulation and several example enhanced oil recovery process simulations were conducted using model parameters obtained experimentally for xanthan biopolymer.
The model consists of three parts. First, a thermal decomposition rate expression for the decline of average molecular weight of polymer was derived from a fundamental consideration of polymer bond breakage. Second, a scheme to calculate the apparent viscosity of polymer in reservoir rock as a function of polymer concentration and average molecular weight was established. Third, a novel simulation scheme was developed that calculates the polymer concentration and average molecular weight as functions of time and position in the reservoir. One advantage of the proposed scheme is that conventional chemical flood simulators can be easily modified to account for the effects of polymer degradation.
Experimental studies to support the model development included measurements of xanthan thermal decomposition rates in brines at low oxygen concentration as well as several other xanthan physical and rheological properties. Results indicated that xanthan decomposition under anaerobic conditions could be modeled as simple random scission of the chain. Average molecular weight could then be directly related to viscosity in the low-shear-rate limit at any concentration through an expression of the Mark-Houwink form and through the empirical Martin equation. The dependence of viscosity on shear rate was described through the Carreau-Yasuda equation and the effects of temperature on the rheogram were predicted with the method of reduced variables. Finally, the viscosity as measured in a viscometer was related to flow properties in porous media through an effective shear rate correlation. Example calculations for a surfactant flood process using this model illustrate quantitatively the impact of high temperature and thermal decomposition on polymer propagation and oil recovery.
Application of Low-Toxicity Crosslinking Systems in Production of Thermally Stable Gels
Authors: Moradi-Araghi Ahmad 
Published: December 2007

Abstract
Earlier reports from our laboratory described a number of thermally-stable water-soluble polymers which tolerate extensive aging times in brines with high salinity and hardness levels at temperatures up to 149° C (300°F). These polymers can be crosslinked with phenol and formaldehyde crosslinking system to produce stable gels under hostile environment conditions typically defined as temperatures higher than 167° F (75° C) and brine hardness levels above 2000 ppm. The resulting gels can be used for profile modification and water shutoff treatments under hostile environment conditions.
In one paper we proposed a mechanism for the gelation of acrylamide containing polymers. This mechanism postulates the formation of salicyl alcohol as an intermediate through the condensation of phenol and formaldehyde. Formation of a thermally stable gel by direct reaction of salicyl alcohol and formaldehyde, with a thermally stable acrylamide containing polymer, is consistent with this mechanism. Concerns about the toxicity of phenol and especially the carcinogenic character of formaldehyde motivated us to search for alternative crosslinkers with lower toxicity, which can be used in place of phenol and formaldehyde to produce stable gels. Through an extensive study, we have identified and tested several compounds which can be used in place of phenol. These compounds include o- or p-aminobenzoic acid, m-aminophenol, aspirin, furfuryl alcohol, methyl phydroxybenzoate, phenyl acetate, phenyl salicylate, salicylamide and salicylic acid. The only suitable compound identified in our study, which can be used in place of formaldehyde and produce stable gels, is hexamethylenetetramine (HMTA), a precursor of formaldehyde. HMTA thermally hydrolyzes to formaldehyde and ammonia at elevated temperatures which will go on to crosslink with acrylamide containing polymers and phenol or its replacements. However, not all formaldehyde precursors can produce thermally stable gels when used in combination with phenol or with an alternative compound to phenol. No suitable gels were produced with glyoxal or 1,3,5-trioxane as formaldehyde precursors.
This paper will describe a number of low toxicity thermally stable gels suitable for applications under hostile environment conditions. The gels described here exhibit a lot of flexibility in terms of gelation time. With the choice of proper crosslinking system, one can produce gels which can set from a few hours to several months. The slower gelation systems could be used for in-depth treatments of hot reservoirs such as those in the North Sea. The bulk gels produced in synthetic seawater or brines containing up to 20% sodium chloride and 2% calcium chloride, have remained stable for several years of aging at 250° F (121° C). This study has only been directed at evaluating thermal stability of bulk gels. The performance of these gels in porous media will be the subject of future studies.
Brine-Initiated Gels: A New Water Shut-Off Agent
Authors: Whittington L. E. , Naae D. G. , Braun R. W. 
Published: December 2007

Abstract
There is increasing concern among domestic operators for reducing water production as fields mature. A new polymer gel, with several unique advantages over conventional gelling systems, has been developed which could serve as a water shut-off agent. The gel forms in place when a freshwater solution of a water-soluble polymer (hydroxypropylcellulose, HPC) and a surfactant (sodium dodecyl sulfate, SDS) mixes with brine. While conventional gels use a chemical initiator or activator, often a heavy metal like chromium, to form the gel, the new HPC/SDS gel uses the salinity of the connate brine to initiate immediate gel formation.
The low-viscosity freshwater HPC/SDS solution injects easily into core material. Upon mixing with the connate brine, a stable high-viscosity gel forms that effectively reduces brine permeability by over 95% in both linear and radial sandstone corefloods. The gel viscosity was measured at about 70,000 centipoise. Permeability reduction is maintained, both in the forward and reverse flow direction, even after several pore volumes of brine flow. In a parallel coreflood test, the gel diverted 90% of the fractional flow of brine.
Progress With Compositional Studies in Heterogeneous Systems for Slightly Submiscible Gas Displacement
Authors: Fayers F. J. , Aleonard Bruno , Jouaux François 
Published: December 2007

ABSTRACT
In this paper we examine factors influencing the characteristics of slightly sub-miscible gas displacement of oil in a heterogeneous system. 2D fine grid compositional solutions are obtained using a fast simulator, MORE, on a Cray YMP computer for a stochastically generated heterogeneity distribution. It is shown that only four pseudo-components are needed to represent the phase behavior adequately and that although fairly low interfacial tensions are obtained, there is not a discernible need to modify the immiscible relative permeabilities. Comparisons are made with heterogeneous results based on the simpler first contact miscible assumptions often used in two-component high resolution simulations of viscous fingering. The fully compositional flow is less unstable than its miscible counterpart, but it is found that the latter can be made to reproduce a compositional solution through reducing the mobility ratio from M = 20 to M = 5. A method for determining this effective mobility ratio is described. Cases with gravity give moderate agreement using M = 5, provided an ad hoc adjustment is also made to the gravity number.
Experimental Study of the Parameters Affecting Cutting Transportation in a Vertical Wellbore Annulus
Authors: Belavadi M. N. , Chukwu G. A. 
Published: December 2007

ABSTRACT
Transportation of cuttings is a mechanism which is a vital factor for a good drilling program. Though many researchers have studied different parameters affecting the transportation of cuttings, a system of equations completely describing the mechanism has not been arrived at. Experimental observation of cutting transportation has been the most effective and accurate method to explain the behavior of cuttings and fluids in the cutting transportation mechanism to a realistic degree of accuracy.
To better understand the effects of some of the parameters affecting the cutting transportation, a well simulation unit was constructed and the transportation of cuttings in the annulus was observed in a test section. The effects of fluid and cutting densities, fluid viscosity, cutting size and pipe rotation were studied using Bingham Plastic fluids of four different densities. The data collected were graphically correlated in the form of non-dimensional units with transport ratio, which was used as a measure of the transportation efficiency.
Analysis of the results showed that the ratio of the density difference between the cuttings to the fluid viscosity had a significant effect on the transport ratio. The effect of density alone on the transport ratio was significant but was not as profound as the density to viscosity ratio. The graphical correlation of transport ratio to the drag coefficient helped to illustrate the magnitude of the effect of drag coefficient on transport ratio.
Sunray Gas Plant: A State-of-the-Art Gas Plant Designed for Today's Environment
Authors: Norton D. G. , Maloney J. J. 
Published: December 2007

ABSTRACT
Maxus Energy Corporation's Texas Panhandle Sunray Gas Plant (70 miles north of Amarillo) is unique, in that it utilizes practically every unit operation available to the gas processing industry (Table 1). This permits extensive processing and operating flexibility, and compliance with tighter environmental criteria, while minimizing operating expenses.
An Economic Assessment of Artificial Lift in Low-Pressure, Tight Gas Sands in Ochiltree County, Texas
Authors: Brady C. L. , Morrow S. J. 
Published: December 2007

Abstract
A review of 289 completions in Ochiltree County, Texas, shows 137 classified gas completions currently produce with the aid of artificial lift. Two methods of artificial lift, beam pumping units and plunger lift, were identified in the review. The study revealed that 130 gas wells produce with the aid of a plunger lift, while only 7 gas wells produce with the aid of a beam pumping unit. This paper reports on historical results obtained from using plunger lift systems. The historical results are compared to published methods for predicting liquid loading and plunger lift production responses. An evaluation of the historical plunger lift production responses and installation workover costs show that an impressive 32 BCF of reserves were added at a cost of less than $0.06/MCF.
How To Conduct an Environmental Audit
Authors: Dancy J. R. , Snell G. A. 
Published: December 2007

ABSTRACT
Environmental legislation enacted over the last several decades has produced a complex matrix of regulations. Environmental compliance now represents a significant cost of doing business, both in terms of the cost of compliance and in terms of the possible penalties and fines which could be incurred as a result of non-compliance.
When making informed corporate decisions involving the acquisition and divestiture of oil and gas properties environmental audits can be used to evaluate the compliance status of a facility.1
Advancements in Two-Phase Slug How Modeling
Authors: Fabre J. 
Published: December 2007

Abstract
Since it was presented by Wallis1 the unit cell model for slug flow has proved its superiority in predicting the phase fractions and pressure gradient with a reasonable accuracy. However it relies on some crucial assumptions and on the choice of four closure laws. These fundamental issues are addressed in the present paper.
On the one hand, the closure laws guarantees the accuracy of the model. The scientific papers provide abundance of these laws whose physical value is unequal. The effectiveness and weakness of some of these laws are discussed from a comparison with existing data. Their critical role for certain ranges of flow rates is emphasised.
On the other hand, some specific assumptions limit the potentiality of the model. In particular the fully developed flow assumption in long bubble and liquid slug is discussed. A route to improve the model is explored.
Barriers to Flow in Tidal Sandstone Reservoirs, Sun Ranch Field, Wyoming
Authors: Tillman R. W. , Pittman E. D. 
Published: December 2007

Abstract
Tidal1y deposited valley-fill sandstones, when sourced from the sea, as is the case in Sun Ranch field, Wyoming, generally form sand bodies which contain smaller pores, (finer grained) and contain significantly more pore throat plugging by detrital (and diagenetic) clay than most superficially similar fluvial or distributary channel sandstones. The detrital clay occurs as thin beds, drapes, clasts and "grains." Calculated log porosities are significantly lower where clay occurs in otherwise high quality reservoir sandstones. The quality of the reservoir is commonly masked on logs by the effect of the clay clasts.
Individual tidal valley-fill deposits are demonstrably separable laterally and generally have several locally continuous horizontal shaley beds which form baffles or barriers that slow or prevent vertical flow. These very thin horizontal beds are: (1) dominantly clay and fine sand and silts deposited during marine to brackish flooding events; (2) are easily recognizable in core but not on most logs; (3) have very low porosity and permeability; (4) prevent or deter vertical flow between reservoir compartments and act as baffles to flow; and (5) are the focus of diagenetic clay formation. Because of the significant amounts of clay present in some tidal and tidally-reworked fluvial valley fills, they have significantly lower porosity and permeability and smaller "port sizes" than most fluvial and deltaic deposits.