bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-Temperature, High-Pressure Rheology of Water-Based Muds
Authors: Alderman N. J. , Gavignet A. , Guillot D. , Maitland G. C. 
Published: December 2007

ABSTRACT
This paper reports measurements of the rheology of a range of water-based drilling muds at temperatures up to 130°C and pressures up to 1000 bar. The fluids are highly thixotropic; decoupling of temperature/pressure effects from those due to time-dependent structural changes was achieved by developing a sample preparation and handling procedure which ensures that all samples experience identical shear histories prior to study in the rheometer. This enabled essentially equilibrium flow curves to be determined over a shear rate range of 0 – 1200 s−1 with a reproducibility of better than ±1 Pa in stress.
The data were best fitted using a three parameter Herschel-Bulkley yield/power-law model although in many cases, particularly at low temperatures and high pressures, the two parameter Casson equation gave an acceptable fit for engineering purposes. For both models the behaviour of the high-shear viscosity reflected the viscous behaviour of the continuous phase: a weak pressure dependence and an exponential temperature dependence matching that of water. The pressure dependence increased with mud density. In all cases the fluid yield stress was essentially independent of pressure. In contrast to oil-based muds, where this quantity decreases with temperature, for these water-based systems it remained constant below some characteristic temperature, whereafter it increased exponentially with inverse temperature.
The physical origins of the observed behaviour are discussed and a simple model for representing the data is given. It is shown how this may be used for reliable extrapolation of surface measurements to downhole conditions for well-circulated water-based muds.
Dynamic Filtration of Bentonite Muds Under Different Flow Conditions
Authors: Fordham E. J. , Ladva H. K. J. , Hall C. , Baret J-F. , Sherwood J. D. 
Published: December 2007

ABSTRACT
The variation of key parameters describing the dynamic fluid loss behaviour of two water-based drilling muds, barite-weighted and unweighted, has been systematically investigated in an annular flow dynamic filtration cell designed to provide well-controlled laminar flows over a wall shear rate typical of those in the wellbore during drilling.
An axial section of the cell inner wall is formed from a 10 millidarcy ceramic filter. The permeability and low particle penetration decouples the cake filtration from formation invasion or formation damage effects. A variable annulus gap was designed to reveal possible Reynolds number effects as well as the dominant wall shear rate effects.
Numerous dynamic fluid loss histories at a filtration pressure of 280 p.s.i. (1.93 MPa) (typical duration 22 hours) show that the fluid loss can be described by three key parameters: one describing the early (‘quasi-static’) behaviour, a second describing the late (‘dynamic’) behaviour of near-constant fluid loss rate, and thirdly a timescale for the transition between these two regimes.
The variation of these parameters with mud flow wall shear rates between 50 and 650 s−1 has been quantified empirically. The early behaviour is virtually independent of shear, but the timescale for transition to ‘dynamic’ behaviour decreases sharply with increasing shear rate from 5 hours to about 14 hour. The final ‘dynamic’ fluid loss rate correlates approximately with the 0.6 power of the shear rate; other theoretically postulated variations are not supported. The irreversible deposition of mudcake under dynamic conditions reported by others has also been observed.
The results have direct application to the modelling of fluid loss in drilling and in well completions. The quantitative laws obtained have also enabled some discrimination to be made between theoretical models for the fundamental mechanisms of mud particle deposition and erosion.
Environmental Impact of Ocean Dumping of Drilling Muds and Cuttings in San Pedro Basin, Offshore California
Authors: Otott G. E. , Mikel T. K. 
Published: December 2007

ABSTRACT
From July 1985 to August 1986 Thums Long Beach Company disposed of waste drilling muds and cuttings in San Pedro Basin of the Southern California offshore area. Higher costs for onshore disposal had made ocean disposal economical during a multi-well drilling program. Ocean dumping was discontinued due to a decline in drilling activity.
Ocean dumping was conducted according to conditions of a U.S. Environmental Protection Agency (EPA) Ocean Dumping Permit for disposal of specific types and amounts of drilling muds and cuttings. A dumpsite specifically for muds and cuttings was designated by the EPA and is located 16 miles from Long Beach Harbor in water depth of 3000 feet. The disposed material consisted of water-based drilling mud and formation cuttings. The drilling mud was similar to Generic Mud #7, one of eight generic muds established by EPA for use in the National Pollutant Discharge Elimination System permit program. The cuttings were from unconsolidated sandstone and shale formations. Disposal of muds and cuttings was via a specially designed barge that can hold up to 6000 barrels of waste material. The muds and cuttings were blended together when loaded onto the barge and the, slurry was pumped overboard through a hose that extended below the water surface.
Ocean monitoring was conducted at the dumpsite during the three year permit period. Ocean monitoring included seafloor sampling and testing, water sampling from surface to 3000 feet, continuous water column profiling, and field verification of the discharge plume model. Results of the water quality and benthic monitoring program show that ocean dumping operations conducted by Thums in San Pedro Basin appear to have had no significant impact on the marine environment. Results of the discharge plume verification study show that the plume was rapidly dissociated and diluted below detection limits.
An Interpretation of the Displacement Behavior of Rich Gas Drives Using an Equation-of-State Compositional Model
Authors: Mansoori J. , Gupta S. P. 
Published: December 2007

ABSTRACT
This paper presents the results of a compositional simulation study to investigate the relationship between the displacement mechanism, the minimum enrichment requirement, and the oil recovery efficiency for a rich gas system. The simulation results indicated that the displacement mechanism over a wide range of solvent enrichment was governed by a condensing/vaporizing process; however, the relative importance of the condensing or vaporizing mass transfer processes, and their impact on the overall displacement efficiency, was a function of the enrichment level. For displacements simulated at or above the slim tube minimum enrichment (ME) level (determined from the recovery breakover point on a recovery versus enrichment plot), recovery was high and the process behaved very similar to a classical condensing mechanism. Displacements simulated below the slim tube ME were less efficient; however, both condensing and vaporizing mass transfer processes contributed to the overall recovery efficiency. At enrichment levels considerably above the slim tube ME, the effect of the condensing mass transfer process on the displacement became less significant and the behavior approached that of a classical vaporizing mechanism.
The slim tube technique for determining the ME requirement based on simulation results was further compared with two other computational methods: one based on Hutchinson and Braun's multiple contact mixing,1 and the other based on displacement behavior at the limit of zero dispersion.2 For this rich gas system, the minimum enrichment level predicted by these methods was significantly higher than the slim tube ME and corresponded to conditions of thermodynamic miscibility development by a classical vaporizing mechanism. Despite such a high enrichment requirement needed to achieve thermodynamic miscibility, the oil recovery did not increase significantly beyond that achieved at the slim tube ME.
Simulation results for the condensing/vaporizing system were also compared with those predicted by a classical condensing mechanism. These comparisons showed that: a) for a classical condensing mechanism, the thermodynamic and the slim tube methods predicted the same minimum enrichment requirement; b) at low dispersion the two mechanisms showed similar displacement behavior; and c) higher values of dispersion had a bigger impact in reducing the displacement efficiency of the condensing/vaporizing mechanism compared with the classical condensing process.
Measurement and Correlation of Miscibility Pressures of Reservoir Oils
Authors: Eakin B. E. , Mitch F. J. 
Published: December 2007

ABSTRACT
Minimum Miscibility Pressures (MMP) for 102 combinations of oils, temperatures, and solvents were observed with a Rising Bubble Apparatus. The data were represented with a 4.5% standard deviation by an equation which needs only the solvent composition, oil C7+ fraction molecular weight, and the pseudoreduced temperature. A slightly better standard deviation of 3.5% was obtained by extending Peng's procedure for critical points of mixtures to calculate MMP.
A Study of Remedial Measures for Water-Coning By Means of a Two-Dimensional Simulator
Authors: Pirson S.J. , Mehta M.M. 
Published: December 2007

American Institute of Mining, Metallurgical and Petroleum Engineers, Inc.
This paper was prepared for the 42nd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Oct. 1–4, 1967. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
A computer program based on the Welge-Weber mathematical model to simulate water coding is developed. Computational characteristics such as rate of convergence, criteria for convergence, level of material balance error, sensitivity of convergence to iteration parameters, grid size and time step size are discussed.
The simulator is verified by studying the effects of various factors such as vertical to horizontal permeability ratio, mobility ratio between oil and water, specific gravity differential between the two phases and flow rate on the advance of a water-cone. The cone shapes and positions are drawn for each case and the results are found to agree with known phenomena.
The model is applied to the study of a stable cone height with known production rates and the results are compared with Muskat's approximate method. Muskat's prediction gives high values for stablized cone positions for reservoirs having a substantial water-oil transition zone.
The simulator is applied to study the relative effectiveness of remedial measures to water-coding such as injection of oil below the perforations, production of water from the underlying aquifer through a double string and the presence of a horizontal impermeable barrier such as a cement pancake.
A new method to prevent water-coning by circulation of oil as a hydraulic doublet placed at the production interval is investigated. It is found to be an effective remedial measure for water-coning problems. The oil doublet so formed is most efficient when its strength is about 20 per cent of the total fluid production.
Reinjection of oil into the reservoir suppresses cone growth in agreement with the Smith-Pirson conclusions. Selective production of water and oil from their respective zones reduces the cone growth, but it gives the same overall water -oil ratio at all times and large volumes of water need to be reinjected for disposal. However, the oil doublet technique appears to be a more suitable remedial measure.
Discount Rates, Cost of Capital, and Property Acquisition Evaluations
Authors: Miller R. J. , Vasquez R. 
Published: December 2007

ABSTRACT
The purpose of this paper is to examine the role of the discount rate in determining the fair market value of a producing oil and gas property; to assess the validity of a discount rate based on a derived source and on an observed or market source, and to evaluate the relationship between discount rates obtained from these two sources. The derivation of a discount rate based on a Cost of Capital approach is compared to the observed effective rate-of-return obtained from analysis of actual producing property acquisitions to (1) determine if a rational relationship occurs between discount rates obtained from the two methods, and (2) how the discount rates obtained from the two methods may reflect changes in the oil and gas industry. The use of derived and observed discount rates in FMV analysis is examined and discussed, particularly as it applies to property acquisitions.
Restructuring of Natural Gas Markets by Regulations and Legislations
Authors: Kumar J. 
Published: December 2007

ABSTRACT
As the natural gas industry in the United States started expanding, states started imposing regulations on the sale, transportation and distribution of gas. In the 1920's, the U.S. Supreme Court issued three famous decisions which spawned the birth of the federal regulation of interstate sale and transportation of gas. In 1938, the U.S. Congress passed the Natural Gas Act (NGA) which empowered the Federal Power Commission to regulate interstate commerce of gas. In 1954, the Supreme Court, in its Phillips Petroleum decision, imposed federal regulation on the wellhead prices of natural gas sold in the interstate market which eventually resulted in low prices and gas shortages in the 1970's. In 1978, the Congress passed the Natural Gas Policy Act (NGPA) which resulted in increased gas prices. The higher prices increased supplies and decreased demand, thus causing a gas surplus. The unprecedented gas surplus in the 1980's resulted in competition at wellhead but this competition could not be extended to the burnertip due to the monopoly ownership of the gas transportation and distribution facilities. In response to this situation, both federal and state regulatory agencies have issued a number of decisions during the last three to four years which are causing a revolutionary changes in the natural gas industry and it is expected that the competitive forces will play a bigger role than at any time in the past in the restructuring of the gas industry.
The Effects of Noise on Interval Correlation Methods Part I: Accuracy and Precision
Authors: Waid C. C. , Faraguna J. K. , Easton S. B. 
Published: December 2007

ABSTRACT
Highly accurate estimates of displacements between dipmeter button curves are essential for computing dips of bedding surfaces. The Pearson product moment correlation coefficient has long been employed to estimate these displacements because it can reduce the effects of uncorrelated, additive noise. Other types of curve similarity measures, namely the L1 and L2 norms, semblance, and the phase correlation coefficient, have similar noise reduction capabilities. This paper reports the results of a comparative study of the effects of noise on the ability of these techniques to accurately estimate displacements. In addition, the effects of displacement magnitude as well as correlation interval length and search length were studied. These experiments indicate that phase correlation coefficient is by far the most accurate of these similarity measures in the presence of uncorrelated, additive noise.
Noise sequences, whose spectra were shaped to cover the range of noise processes encountered during well logging, were added to both real and artificial button data to achieve a wide range of signal-to-noise ratios. Each correlation method was used to estimate the displacements between the noisy curves. The probability of finding the exact displacement as well as the distribution of displacement error was computed.
Design and Evaluation of Pumpin Temperature Surveys for Detecting Cement Channels above Perforations
Authors: Bergren F. E. , Bradley D. A. 
Published: December 2007

Abstract
Movement of fluids in cement channels outside of well casing is a frequently-occuring problem in the production of hydrocarbons. This may result in cross-flow between formations, or fluids being injected into – or produced from – unintended formations. Although channels above perforations are sometimes suspected, their existence is often difficult to detect. An improved method of detecting channels above perforations was developed by computer simulation and correlation of field data. This method, the pump-in temperature survey (PITS), has been proved reliable with recent usage on producing wells at the Prudhoe Bay Field.
A wellbore simulation computer program was used to determine the thermal state of a well during a PITS assuming various combinations of pumped fluid inlet temperature, flowrate, and volume. An optimum volume of pumped fluid to achieve the required temperature depression at the perforations was thus determined. Also, relationships between easily-calculated and measured parameters and the interpretability of PITS logs have been determined. The most important variable in PITS design was found to be pumped volume. The success of a PITS log is also dependent on the temperature depression experienced at the perforations. These findings have been incorporated into design and logging recommendations.
The results of several successful PITS logs are summarized to illustrate the relationship of PITS log response to the existence of cement channels. This summary of log responses may be used as a guide to interpret future PITS logs.
The PITS logs run recently at Prudhoe Bay have shown that, in most cases, it is possible to determine if a channel above the perforations exists. Although a PITS designed to find a channel above the perforations requires substantial logging finesse, it is more economical than the alternatives (cement quality logs and radioactive-tracer logs).
A Technique for Evaluation of Hydraulic Fractures Using Quantitative Concentrations Derived from the Natural Gamma Ray Spectrum
Authors: Jackson C. E. , Gartner M. L. 
Published: December 2007

Abstract
Logging tools that record the entire natural gamma ray spectrum are designed to measure concentrations of the naturally occurring radioactive elements Potassium (K), Uranium (U), and Thorium (Th). Concentrations are determined by applying a device-dependent algorithm to the counts in three or more energy windows (regions of the spectrum).1 A similar technique is used to evaluate induced fractures where the fracturing fluid and/or the proppant is tagged with radioactive tracers (such as Scandium-46 or Iridium-192). The concentration of each tracer element after fracturing operations is used to determine the extent of the fracture network.
A sophisticated mathematical method is used to compute the calibration spectrum for each of the tracer elements in a range of environments. The Boltzmann transport equation is solved for the gamma ray flux at the detector surface and convolved with a detector response function determined by Monte Carlo simulation to obtain the spectra. Once properly calibrated, a spectral stripping technique computes quantitative concentrations for all radioactive isotopes in the formation.
Techniques for utilization of these concentrations is discussed. Several log interpretation examples illustrate the discussion.
Reservoir Modeling of Marginal Aeolian/Sabkha Sequences, Southern North Sea (U.K. Sector)
Authors: Martin J. H. , Evans P. F. 
Published: December 2007

ABSTRACT
Sedimentological core description, log-facies interpretation and well correlation demonstrates the vertical heterogeneity but lateral homogeneity of Permian Rotliegend gas sands in the North Viking Field area. Here, marginal to the main dune belt, the sequence is strongly layered with a harsh permeability distribution.
Intercalated sabkha facies form potential vertical permeability barriers. It is inferred that these represent lacustrine transgressive horizons passing laterally into major first order bounding surfaces formed by the deflation of dune sands down to the water table. Even beds less than 0.5m thick are laterally extensive: detailed correlation has been achieved over a distance of 35km parallel to depositional strike, and 15km parallel to depositional dip.
These conclusions contrast with those of previous work carried out in this area, and differ from a generalised reservoir model for this environmental setting.
Pressure Transient Analysis of Wells with Finite Conductivity Vertical Fractures in Double Porosity Reservoirs
Authors: Cinco-Ley H. , Meng H. -Z. 
Published: December 2007

ABSTRACT
This paper presents the results obtained in the study of the transient behavior of a well intersected by a finite conductivity vertical fracture in a double porosity reservoir. Two models are considered to take into account the fluid transfer between matrix blocks and fractures: the pseudo-steady-state matrix flow model and the transient matrix flow model.
A general semianalytical model and simplified fully analytical models are presented. It is demonstrated that these systems exhibit the basic behavior of a well with a finite conductivity fracture: that is bilinear flow, pseudolinear flow and pseudoradial flow in addition to the transition flow periods. Each of these flow periods is under the influence of the different states of the fluid transfer between matrix and fractures; that is fracture dominated period, transition period and total system dominated period.
It is shown that correlating parameters are the dimension-less fracture conductivity (kfbf)D, the fracture storativity coefficient ω and the interporosity flow parameter λf(or the dimension-less matrix hydraulic diffusivity ηmaD).
It was found, for the transient matrix flow model, that the pressure behavior exhibits 1/8 slope in a log-log graph during the bilinear flow dominated by the transition period of the fluid transfer. Hence a graph of pressure versus t1/8 yields a straight line passing through the origin.
During the pseudolinear flow, and if the fluid transfer is in the transition period, a log-log graph of the prerssure versus time exhibits 1/4 slope straight line. This means that a graph of p versus t1/4 yields a straight line. Hence it is concluded that bilinear flow is not the only type of flow that exhibits the one quarter slope type of behavior.
Type curves are presented to analyze data falling in the bilinear – pseudolinear flow regions. The effect of wellbore storage are also included. The general semianalytical models yields simultaneous the constant flow rate and the constant pressure solutions as well as the pressure derivative function for the constant rate case.
Well Test Intepretation for Naturally Fractured Reservoirs
Authors: Stewart G. , Ascharsobbi F. 
Published: December 2007

ABSTRACT
An analysis of a large number of well tests in naturally fractured reservoirs has confirmed the validity of the pseudo-semi-steady-state model of matrix block support. This is due to interporosity skin as a result of fracture face alteration. Fracture network theory shows that wells in fractured reservoirs should exhibit a negative skin for an ideal connection to the fracture system. A new dimensionless derivative type curve for estimation of dual porosity parameters has been developed.