bluuebunny/crossref_metadata_2025_split huggingface dataset:
Report on MWD Experimental Downhole Sensors
Authors: Grosso Donald S. , Raynal Jean C. , Rader Dennis 
Published: December 2007

Summary
Measurement while drilling (MWD) provides a means for monitoring drilling and formation parameters as drilling progresses. The technique, based on the use of advanced downhole sensor and telemetry technology, makes possible the real-time acquisition of data that was previously impossible without stopping the drilling previously impossible without stopping the drilling operation. Some downhole data, such as weight and torque on bit (WOB and TOB) can be obtained only while drilling.
In Summer 1976, Teleco Oilfield Services began an experimental program to demonstrate the feasibility and usefulness of a multisensor MWD tool for real-time measurement of drilling mechanics, formation evaluation, and well-control parameters. A package incorporating six sensors was designed and implemented in a downhole tool capable of transmitting data to the surface by means of mud-pulse telemetry.
In this paper we discuss the experimental 6-sensor tool and representative results obtained in a series of 12 field tests in various pails of the world, both onshore and offshore.

Introduction
The MWD tool was introduced in Aug. 1976 on a limited basis. It was designed to provide the directional-drilling industry with real-time measurements of hole deviation, azimuth, and tool facing. Full commercial directional service was made available in the Gulf of Mexico and the North Sea in Sept. 1978. In a parallel effort begun in 1976, an experimental system was built to demonstrate the broader potential of down hole MWD technology for enhancing the safety and efficiency of dulling while simultaneously obtaining formation-evaluation data. Two prototype MWD tools incorporating six downhole sensors and using mud-pulse telemetry were built. More than 1,200 hours of continuous mud-pulse data transmission were accumulated in the field test program.

Telemetry System
Mud-pulse telemetry is a wireless means of communicating data from downhole to the surface. Information in the form of binary bits is communicated through a sequence of pressure pulses generated in the mud column within the drill pipe by a valve located in a special sub near the bit. This information, in the form of pressure waves, propagates through the drilling mud and is detected and displayed at the surface. This technique imposes no restrictions on the drilling operation, is rugged, reliable, safe, and only marginally affected by mud composition or depth.
So far, MWD technology has been applied primarily to directional surveying. Its use in other applications, such as formation evaluation and drilling efficiency, offers great promise to the oil and gas well drilling industry. In the balance of this paper, some of these applications are discussed on the basis of an extensive series of tests with the experimental six-sensor MWD tool. Additional discussions of MWD technology and applications are found in Refs. 1 through 4.
The essential elements of the telemetry system consist of the transmitter and surface receiving equipment.
JPT
P. 899
Surfactant Retention in Berea Sandstone— Effects of Phase Behavior and Temperature
Authors: Novosad J. 
Published: December 2007

Abstract
Experimental procedures designed to differentiate between surfactant retained in porous media because of adsorption and surfactant retained because of unfavorable phase behavior are developed and tested with three types of surfactants. Several series of experiments with systematic changes in one variable such as surfactant/cosurfactant ratio, slug size, or temperature are performed, and overall surfactant retention then is interpreted in terms of adsorption and losses caused by unfavorable phase behavior.
Low-Permeability Laboratory Measurements by Nonsteady-State and Conventional Methods
Authors: Freeman David Louis , Bush Darrell Cleo 
Published: December 2007

Abstract
Evaluation of tight gas reservoirs requires an accurate but rapid and practical method to determine permeability. Such a method is presented for determining both specific and effective gas permeability in the 0.0001- to 0.35-md range for plug-size core samples.
Equipment is described that meets the requirements for calculation of nonsteady-state flow and incorporates the capability of simulating high net overburden pressures by either hydrostatic or triaxial confining pressures with ease of operation. The time required to collect data and calculate Klinkenberg permeability is typically less than 6 minutes per sample. Values normally differ by less than ±5% from those obtained by steady-state methods. This method is well suited for routine laboratory determinations of permeability on samples from reservoirs with tight or very low gas permeability.
Effective gas permeabilities on samples containing nearly irreducible water saturations and the water permeabilities presented are closer to the Klinkenberg permeability values in low-permeability samples than most previously reported.
Production Behavior of Prolific Gas Wells and Optimal Production Policy for a Gas-Reservoir Complex
Authors: Dietz D.N. , Scholten P. , Wilms H. 
Published: December 2007

Summary
A new and simple decline formula facilitates the search for an optimal policy of production with or without compressers from a number of gas reservoirs of different characteristics. Optimizing production policy traditionally is carried out by trial and error. The paper leaves this procedure essentially unaltered but reduces the computer time per trial, thus allowing more trials. Results of some sample calculations are presented.

Introduction
Where numerous wells producing from several as reservoirs feed into a common pipeline system, a great number of alternative production policies present themselves, especially where gas has to be compressed to bring it up to pipeline pressure. To study the alternatives one needs the basic information regarding performance of the individual wells. To describe such performance one may choose among several formulas available in the literature, which are all based on the assumption that, apart from pressures. the physical conditions remain unchanged. A prudent prediction. however, will allow for possible deterioration or even complete loss of one or more wells. On the other hand, one is at liberty, of course, to postulate replacement and infill drilling. Performance of a future producer has to be estimated. Hence the combined performance of all wells in a single gas reservoir can be predicted with only limited accuracy.
Once this unavoidable inaccuracy is accepted we must conclude that it is not justified and not desirable to waste computer capacity on excessively accurate well production performances-, computer capacity is employed more usefully on a large number of alternative production policies.
This philosophy is worked out in the following chapters. For the time being, we have limited ourselves to reservoirs, without water drive.

Performance and Decline
Traditionally, inflow performance is defined as the dependence of production rate on bottomhole pressure (BHP). At low rates Darcy's law prevails and the inflow expressed at standard conditions is described by
q = C (p2-pw2) (1)
This formula is obtained by assuming that the gas has a constant viscosity and follows Boyle's law.
At higher rates the flow becomes turbulent in the proximity of the well. There is an upstream section with a linear resistance and a downstream one with a quadratic resistance This leads to
(2)Aq+Bq2=p2-pw2
This well-known formula is not exact, because the higher the rate, the longer the section with a quadratic resistance.
JPT
P. 2285^
Generalized Theory for Evolution and Dispersion of H2S From Alkaline Muds
Authors: Wendt Richard P. 
Published: December 2007

Abstract
This paper develops a general theory to describe the evolution and dispersion of H2S from alkaline drilling mud into which CH4, H2S, and CO2 have intruded downhole. The theory is based on an assumed general form for the electrical neutrality condition between all dissolved ionic species. Also assumed operative are mass-action laws for the several sulfide and carbonate species and Henry's law for the partial pressure of CO2 and H2S above the mud. These constraints and a modified form of the Pasquill-Gifford equation are then used to calculate H2S levels at any position downwind from the wellhead. Required input variables for the calculation include the initial pH and Pm of the mud, the mud flow rate, total gas intrusion rate, and mole fraction of H2S and CO2 in the intruding gas. The theory provides a rational model for estimating effects of these variables on gaseous H2S levels downwind and indicates severe limitations on the alkaline method for controlling sour gas intrusions.
Economic Factors in Bank Loans on Oil and Gas Production
Authors: Dodson Charles R. , McGee John S. 
Published: December 2007

Introduction
As is now well known, oil producers borrow from banks for operating and capital purposes, including the development and purchase of producing properties. Sound bank loans on oil and gas producing properties depend on a thorough analysis and correct evaluation of numerous credit considerations. These can be segregated, for convenience, into five major groups: management, engineering, legal, regulatory and economic.
All are important to banks. Heretofore, only management and engineering, and to a lesser extent, legal and regulatory considerations have been popular topics for analysis. Purely economic considerations appear to have received too little publicity.
Consequently, our purpose here is to remedy this situation in part by the discussion of several of the important economic considerations and to explain why we think they are important. However, before proceeding we should first review the nature and requirements of commercial banking in order to understand why lending officers must consider these economic factors.

Banker's Point of View
Bank officers are prudent and enterprising business men, capable of evaluating potential loans in the light of the bank's lending and liquidity policies. Bankers respect and honor the requests and needs of their customers who have established banking relationships; i.e., those who have used credit, deposit and other bank services. In the case of loan applications from new customers, the banker is interested in the long-run potentiality for a growing relationship in regard to deposits and use of bank services as well as future loans. A banker has in mind not only his obligations to stockholders and depositors, but also the legal requirements and the relatively low rate of return on loans. Further, the bank must help the borrower to avoid difficulties and accomplish efficiently his financial objectives. Frequently, businessmen do not fully appreciate these obligations and restrictions or realize that these are applicable to oil loans.
The petroleum industry is a complicated giant composed of many interrelated segments - producing, transportation, refining and marketing - which are vital to our economy. As we hope to show later, the industry regardless of its huge size is not independent of or isolated from the national economy. If this is true then sound loans in the oil producing segment require not only a thorough and current knowledge of the industry, but a "feel" for economics as well. This is equally important to the borrower in order to tailor a loan that properly fits his needs and capacity to repay as promised.
Multiphase Dispersion and Relative Permeability Experiments
Authors: Delshad M. , MacAllister D. J. , Pope G. A. , Rouse B. A. 
Published: December 2007

AbstractExperiments in both Berea sandstone and sandpacks have been conducted to measure dispersion and steady-state relative permeabilities. Measurements have been made on both high-tension brine/oil and a low-tension, three-phase, brine/oil/surfactant/alcohol mixture. One interesting aspect of these experiments is the amount of microemulsion phase trapping. The endpoint microemulsion saturations for both the oil/microemulsion and brine/micro-emulsion phase pairs were high even at 10−3 dyne/cm [10−3 mN/m] interfacial tension (IFT). The dispersion was measured for each phase with radioactive and chemical tracers. The dispersivity was found to be a strong function of phase, phase saturation, porous medium, and IFT. Values of the dispersivity varied by two orders of magnitude over conditions investigated to date. Extremely early breakthrough of the tracer used in the oil phase (carbon 14) at high tension is especially remarkable. The brine tracer (tritium) curves were similar to that for 100% brine saturation except for a shift caused by material balance reasons. The classical solution to the convection-diffusion equation for single-phase flow has been generalized to multiphase flow and was used to aid in interpreting these data. This combination of relative permeability and dispersion in each phase of the experiment with a high-concentration, three-phase-microemulsion sulfonate formulation is believed to be new, and more directly applicable to commercial surfactant flooding than previously reported experimental results.
The Thermal Recovery Process - An Analysis of Laboratory Combustion Data
Authors: Benham A.L. , Poettman Fred H. 
Published: December 2007

Abstract
By considering the stoichiometry of the underground combustion process, an equation was derived relating the point velocity of the combustion front as a function of the air flux, fuel content, efficiency of oxygen utilization, hydrogen:carbon ratio, and ratio of carbon dioxide to carbon monoxide produced. In addition, an equation for calculating the amount of injected air necessary to produce the oil from 1 cu ft of reservoir space was derived. This equation has a direct bearing on evaluating compression costs for the process. Values calculated from these equations are in good agreement with experimentally observed values obtained from laboratory tube runs reported in the literature. The equations are also useful for analyzing experimental data for inconsistencies.

Introduction
The injection of energy in the form of heat into an oil-bearing formation as a means of increasing the recovery of oil has been the subject of much discussion and experimentation as far back as 1920. The ideas have ranged from the injection of steam to the direct use of electricity as a means of getting thermal energy into a formation.
However, most laboratory and field studies have been confined to the process whereby a portion of the crude in the reservoir is burned to generate the necessary heat to increase the mobility of the oil by reducing its viscosity. A recent paper by W. L. Martin, et al. described the results of a number of laboratory experiments in which the combustion process was studied in a sandpack. Studies such as this indicate that with the temperatures involved, the oil is partially coked in this process and it is this coke which provides the fuel for combustion. The combustion of this residual coke can be analyzed theoretically by applying simple stoichiometric principles to the combustion process.
It is the purpose of this paper to compare the results reported in these experiments with those obtained from theoretical considerations.
Porosity Balance Verifies Water Saturation Determined From Logs
Authors: Tixier M.P. 
Published: December 2007

Abstract
In several log interpretation methods, water saturation is evaluated by use of the ratio of the readings of a short spacing resistivity device and a long spacing resistivity device plus information on the mud filtrate and connate water resistivities, which is often derivable from the SP. These methods are valid over a certain range of conditions, usually specified by moderate invasion and Rxo greater than Rt. Since these methods involve no explicit evaluation of the formation factor, F, the saturation so found may be used in the standard Archie equation to derive a computed formation factor which, as a check, may be compared with the formation factor known from other independent measurements. Discrepancies in the two values of formation factor generally indicate that the ratio method is not within its range of applicability. If the computed F is too low, the corresponding Sw is too low; if the computed F is too great, the corresponding Sw is too great. By means of this "porosity balance" check, and some knowledge of the probable conditions of invasion, the interpretation can often be improved.
The porosity balance check is discussed for the cases of the Induction-Electrical Log Interpretation Method, the Rocky Mountain Method, and the Rxo/Rt Method. For the first method, a discussion is also given for the case of shaly sands.

Introduction
Although many logging tools are available to obtain a practical value of porosity, the only logging method reflecting the water saturation is electrical logging.
Water saturation is commonly computed from electrical log data by means of the basic Archie formula,
(Equation 1)
where F is the formation factor, Rw the resistivity of the formation water, and Rt the true resistivity of the formation.
One difficulty in this procedure is a possible error in the evaluation of Rt from the logs - for example, in the case of very deep invasion. There is no possibility, inherent in the procedure, which would provide a check of the accuracy of Rt and, hence, of the computed saturation.
Pipe Viscometer Study of Fracturing Fluid Rheology
Authors: Rogers Rudy E. , Veatch Ralph W. , Nolte Kenneth G. 
Published: December 2007

Abstract
The large increase in the use of crosslinked fracturing fluids in the past decade has led to the need for accurate evaluation of their flow properties. Traditional rotational viscometers are inadequate for studying the rheology of these crosslinked fracturing fluids, hereafter called "gels." A recently developed coiled-pipe viscometer is described, and gel response to various temperature and shear histories during preparation and testing is presented as determined by the pipe viscometer.
If gel flow properties in the fracture are to be studied accurately with any viscometer, then preparation of the gel, thermal energy input, and mechanical energy input to the test sample should be controlled to duplicate the gel of the fracture. The pipe viscometer developed has the following attributes.
Gel preparation is an integral part of the viscometer. Each element of the gel is subjected to the same degree of shear while mixing. The gel develops in-line as it moves to the test section of the viscometer. There are no stagnant periods. Heat transfer occurs from the walls of the conduit to the fluid in flow as in the fracture. Parallel flow sections are incorporated for scale-up information.
Results are presented to elucidate the mechanism of gel formation and deterioration, gel stability at high temperatures, and the possible occurrence of slip flow in the fracture. The coiled-pipe viscometer shows potential to stimulate fluid preparation and flow in the fracturing process.
Migration of Alkaline Pulses in Reservoir Sands
Authors: Bunge A. L. , Radke C. J. 
Published: December 2007

Abstract
Establishing the amount of alkali loss by rock reactions is critical because successful application of most alkaline flooding techniques requires that hydroxide propagate through a large portion of the reservoir. This paper presents a mathematical analysis of the chromatographic movement of alkaline pulses when they are scaled to reservoir flow rates and distances. Using only this analysis and laboratory data, we show how to estimate the distance an alkaline pulse traverses under field conditions before its concentration diminishes to ineffective levels.
Laboratory core tests and X-ray analyses identify the various mineral reactions and their rates. For clayey sands a fast, reversible, sodium/hydrogen ion exchange retards alkali concentration velocities. Fine silica and quartz are suggested as important dissolving minerals, with slower-dissolving clays and clay minerals releasing soluble aluminum, which may redeposit with soluble silica as new aluminosilicate minerals. While new mineral formation influences the aqueous aluminum and silica concentrations, hydroxide consumption appears to be controlled mainly by the dissolution reaction. First-order kinetics most closely represent the dissolution behavior; lumped-parameter rate constants are reported for Huntington Beach and Wilmington sands and for a Berea sandstone.
Computing Thermal Neutron Decay Time Environmental Effects Using Monte Carlo Techniques
Authors: Preeg W. E. , Scott H. D. 
Published: December 2007

Summary
Time-dependent, three-dimensional (3D), coupled-neutron/gamma-ray Monte Carlo calculations were made for both thermal neutron decay time (TDT-K™ and TDT-M™) logging systems. Calculations were made for different borehole sizes, casing sizes, and different formation and borehole macroscopic capture cross sections (Σ). Good agreement was obtained between our calculations and laboratory TDT measurements.
Monte Carlo calculations were made to separate the contributions to the detector count rates resulting from gamma rays produced in various regions, such as the borehole fluid, casing, cement, and those produced in the formation. The decay rates resulting from these various components show how the measured Σ may differ from the intrinsic formation Σ and lead to a better understanding of the relationship between the near- and far- detector measurements. The calculations also provide information on the bed-thickness response of the TDT.