bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Hydrates: Occurrence, Production, and Economics
Authors: Iseux J-C. 
Published: December 2007

Abstract
Gas Hydrates – Occurance, Production and Economics
Gas hydrates are crystalline compounds stable under particular conditions of low temperature and high pressure. Relatively large quantities of methane can be trapped in small volumes of hydrates, which represent a substantial in-situ natural reserve and ressource in the shallow crust.
In order to recover natural gas from this resource, it is necessary to dissociate the water structure and remove the gas. This is the reason why a new method is put forward:
Hot Solvent Stimulation after Hydraulic Fracturing, with a method called S.T.S.F. The technique resembles Acid Fracturing but replaces Acid by Hot Solvent for the hydrate dissociation. Moreover, the method can be improved by drilling a second production well in order to control the solvent flow in the fracture and the gas production. The shape of the fracture can be either horizontal or vertical depending on the depth and the in-situ stresses.
The following paper describes the development and applications of a heat transfer model, as well as the flow through the dissociated zone by leak-off from the fracture. The analytical solution, obtained through the introduction of some simplifying assumptions, has two main advantages: it can be used without any digital computing equipment and can be easily handled by field engineers.
Graphical results indicate that with S.T.S.F. method gas production and the energy efficiency ratio are three times as high as with any method.
The paper ends with an attempt to analyse the economics of natural gas production from gas hydrates, assuming a satisfactory method of hydrates recovery.
Integration of Cement Job Data for Better Bond Index Interpretation
Authors: Jutten J. , Toma I. , Morel Y. , Ferreol B. 
Published: December 2007

Abstract
Cement job evaluation has always been a major problem. Acoustic and ultrasonic logs are widely used to assess the quality of the cement job but even experts experience difficulties in locating cement on a bond log.
Bond Index (BI) has been the only interpretation method to make quantitative evaluation of the cement job. Un-fortunately, BI is far from being an exact figure and in many cases it will not be a valid method to use. Moreover, whenever BI is valid, it is very difficult at present to choose the right references for doing the interpretation. This paper demonstrates that the evaluation of cement jobs can be significantly improved when the design and actual cement job data are taken into consideration. Integration of this data, linked to characterizing the cement by its acoustic properties rather than its compressive strength, allows a calculation of all reference values for a better BI interpretation, and prevents misinterpretation in many cases. Field cases are also discussed which show the validity and the added benefits of the new integrated approach.1
A Comparison of Beam and Submersible Pumps in Small Cased Wells
Authors: Butlin D. M. 
Published: December 2007

Abstract
Using capital and power cost as measures, a comparison is made of the two most popular forms of artificial lift: beam pumps and submersible pumps. After discussing the difficulties involved, and simplifications required in making the comparison, limits of operation are established and a common range of depths and rates suitable for both techniques is found. Within this range many sets of equipment are sized, using computerized selection programs, and capital and power costs are calculated. The results are compared and a total ‘10 year cost’ is estimated for each unit. Capital costs are found to be higher for beam pumps, but power consumption is less. Charts summarize the findings for easy reference.
Performing Workover Drilling Operations Through Small-Diameter Restrictions
Authors: Fultz J. D. , Pittard F. J. 
Published: December 2007

ABSTRACT
In the effort to reduce costs, many companies are investigating the cost effectiveness of completing some types of workover operations without removing the production tubing. These operations include scale removal, frac sand removal, squeeze-reperfing, underrearning and junk/fish removal. All of these operations are currently feasible using either slimhole work strings or coiled tubing in conjunction with slimhole PDM's. This paper describes the tools and procedures used to complete these operations and compares their cost effectiveness with conventional operations. A section is included on new tools being developed which should broaden the scope of these operations. The paper concludes that slimhole workover drilling operations can provide sub-stantial economic benefits compared to conventional workover methods.
Cathodic Protection Maintenance/Monitoring on Oilfield Well Casings
Authors: Garg Arvind K. , Wegener Delano P. 
Published: December 2007

ABSTRACT
This paper describes a new software program developed for the maintenance/monitoring of cathodic protection systems on oilfield well casings. The program was a joint effort by Mobil E&P U.S. and EMDT.
Due to Mobil's large number of cathodically protected wellbores in Oklahoma, a suitable computer program for monitoring well casings was necessary. Although many computer programs have been developed for the monitoring of cathodically protected pipelines, these programs did not satisfy the well casing need because of differences in systems.
The software program developed satisfies all the reading requirements for the corrosion engineer, yet is simple enough for everyday use by field personnel. In addition, due to a large geographical area, an adequate means of data transmission also had to be established so that appropriate control could be maintained from a central location.
Two-Phase Flow Correlations as Applied to Pumping Well Testing
Authors: Kabir C. S. , Hasan A. R. 
Published: December 2007

AbstractIn a pumping-well buildup test, computation of bottomhole pressure (BHP) and flow rate (BHF) requires the use of a two-phase flow correlation for estimating the gas void-fraction or holdup along the pipe length and shut-in time. Various correlations are available to perform this task.The purpose of this work is to review these two-phase correlations and to provide an objective evaluation. This analysis is necessitated by the fact that considerable differences in BHP and BHF may occur-depending upon the correlation used-in wells with long pumping liquid columns or those that have high gas/liquid ratio production. Consequently, a potential exists for obtaining different reservoir parameters from transient interpretation.Using laboratory data for two-phase flow in annular geometry, relative strengths of these correlations are explored. Our own data and those of others (a total of 114 points) are used in this comparative study. For static liquid columns, the correlations of Hasan-Kabir, Gilbert, and Podio et al. provide acceptable agreement with experimental data, exceptions being the Godbey-Dimon and Schmidt et al. correlations. In contrast, for the moving liquid column scenario, as in a buildup test, the Hasan-Kabir model provides the best agreement with the dataset used in this work. A basis for smoothing the bubbly/slug transition boundary is given for the Hasan-Kabir method, together with a field example.
Selection of High-Alloy Tubulars for the 823 Field (Mobile Bay)
Authors: Wilhelm S. M. , Currie D. M. 
Published: December 2007

Abstract
The paper provides laboratory test data that was used to select high strength, nickel base alloy, production tubing for Mobil's 823 field. The application is of critical importance because of the large quantity of H2S (0.5 to 5 mole percent at 20,000 psi BHP) present in Mobile Bay wells. A rigorous test and evaluation program was required to ensure that the selected tubulars are immune to stress corrosion cracking and localized corrosion. New test methods consisting of slow strain rate experiments and critical pitting temperature tests were employed to diagnose temperature limitations and alloy class suitability.
The data suggest that some alloy types may exhibit an localized corrosion and stress corrosion cracking at intermediate temperatures (250 – 350 F). The intermediate region of temperature in which cracking is seen for cold worked high alloy tubing is a novel observation for sour gas well environments and is associated with situations in which the normally protective chromium oxide on the metal is transformed to a predominantly sulfide film. Elemental sulfur was found to have a major influence on cracking susceptibility.
This research supports the economic selection of high alloy tubing for critical applications such that the alloy content is matched to the actual field requirements this resulting in significant cost savings. Reliability of production equipment is maximized by a firm understanding of degradation mechanisms and temperatures.
Effect of Sidewell Completion on Steamflood Performance of Inverted Nine-Spot Patterns
Authors: Hong K. C. , Ziegler V. M. , Peacock S. M. 
Published: December 2007

ABSTRACT
A numerical simulation study was undertaken to determine the best completion scheme for the sidewell in an inverted nine-spot pattern. Simulation results showed that completing the sidewell across the bottom 20% (1/5) of the target interval produces the largest cumulative oil at the lowest cumulative steam-oil ratio. This completion scheme was found to be best regardless of the pattern size (2.5 or 5.0 acres) and the initial reservoir temperature (90 or 200°F).
If an intermediate shale lense is present in the sand, the oil additionally recovered by partially completing the sidewell over that by fully completing it decreases with a decrease in vertical permeability of the shale lense. This results because the effects of steam override and gravity drainage diminish with decreasing vertical permeability.
Environmental and Permitting Considerations for Causeways Along the Beaufort Sea, Alaska
Authors: Robertson S. B. 
Published: December 2007

ABSTRACT
One of the environmental constraints on oil and gas development on the North Slope of Alaska has to do with the need for causeways. Causeways have been used to support docking facilities, drilling and production facilities, and waterflood sea water treatment plants. The design preferred by industry is a solid-fill, gravel causeway. Many governmental permitting and resource agencies feel that the environmental effects of this design are unacceptable. Two solidfill gravel causeways have been built in the vicinity of Prudhoe Bay. It has been found that some alteration to circulation patterns and localized, temporary changes in nearshore fish habitat results from the presence of these structures. While some fear that this puts the fish populations at serious risk, no effects on the local fish population have been found. Nevertheless, other, more expensive and technically unproven (in Arctic) options, such as subsea pipelines and bridge type structures, have been proposed, as environmentally preferred alternatives. These should be site specific decisions. The increased difficulty in obtaining permits for gravel causeways may result in not being able to develop some nearshore reservoirs.
Risk-Weighted Optimization for Cyclic Steam Stimulation of Water-Underlain Reservoirs
Authors: Mehra R. K. , Ding L. Y. , Donnelly J. K. 
Published: December 2007

ABSTRACT
The paper describes the procedure that was adopted to develop operating guidelines for the cyclic steam stimulation process in a water underlain oil sands reservoir. The study consisted of three parts: i) The risks associated with fracturing into water sands were quantified by conducting a stochastic simulation; ii) Numerical simulations were conducted to obtain correlations among the cumulative production volumes and six selected operating variables; iii) These correlations were subsequently embodied in the economic model to maximize the profits under different constraints.
The study concluded that rather than a unique value, a wide range of operating conditions maximized the project profitability. It recommended that a cautious approach in exploitation of these resources was warranted since the penalty for selecting non-optimal conditions was not high.
Effect of Ranking Criteria on Development Goals in Capital and Manpower-Limited Oil and Gas Organizations
Authors: Starzer M. R. 
Published: December 2007

ABSTRACT
This paper summarizes a study to determine the effect of financial ranking criteria on development goals of oil and gas organizations. Economic analysis and ranking was applied to one hundred projects representing oil and gas investment opportunities available to an organization. Each project's after tax cash flows were subjected to four financial analysis methods for ranking. The four analysis methods used were net present value to investment ratio (NPVI), internal rate of return (IRR), payback period and profit to investment ratio (P/I). After ranking, the projects were totaled according to a particular organizational objective. Totaling of projects by ranking would continue until a limiting resource to the organization was exhausted.
This study demonstrates the insensitivity of financial analysis methods for ranking whether the organization is limited by capital or manpower. It concludes that the only requirement for a ranking criterion to properly allocate resources is that the criterion quantifies the organizational goal to some degree. Decision makers charged with selecting the most attractive growth portfolio of investment opportunities will do well with any profit measuring criterion for ranking.
A New Logging Method for Enhanced Coal Grading
Authors: Johnston D. J. , Gales R. H. , Ahmed U. 
Published: December 2007

ABSTRACT
The new surge in drilling for coalbed methane gas has increased the need for quantitatively defining the grade of the various coal seams. The most common measurement for grading the coal seams has been through the use of formation bulk density. Empirical algorithms have been developed which use the formation bulk density to rank coal in terms of proximate analysis. Such empirical analysis has also made use of the Litlio-Density (LDT*) with its Photo Electric Factor (PEF), neutron, and resistivity measurements in recent years. New methods need to be developed that do not depend on empirically derived algorithms so that the coal grading analysis can be significantly improved.
The addition of data from the Geochemical Logging Tool (GLT*) to a LDT/CNL (Compensated Neutron Log) and resistivity logging suite offers such an opportunity. The GLT measures natural activation and prompt neutron capture gamma rays from which it produces measurements of the most abundant, and a few trace inorganic elements. This paper illustrates the need for development of a coal ranking and grading model based on the elemental analysis. For proper application of the model, it is necessary for it to be calibrated to core measurements (ie. rank of the coals).
Laboratory Tests To Determine Parameters for Hydraulic Fracturing of Coalbed Methane
Authors: Penny G. S. , Conway M. W. , Klem R. C. 
Published: December 2007

ABSTRACT
A series of laboratory experiments have been conducted with specially designed equipment to aid in quantifying the pressure drop of proppant-laden slurries while flowing between coal, and measuring the conductivity of various proppants once placed in a coal fracture.
The rheology and proppant transport of borate-crosslinked fluids with and without proppant has been evaluated in a slot with walls cast from the surfaces of fractured coal, in an effort to quantify the impact of tortuous coal fractures on the pressure drop down the fracture. A second device has been constructed to view the flow of slurries through cleats of various sizes. Data is presented on the measurement of pressure increases due to bridging vs cleat size, proppant size, concentration and rate.
The long-term conductivity and permeability of various sands have been measured between fractured Fruitland Coal. Predictive equations have been developed to predict permeability between coal vs sand sieve size, and predict loss of permeability due to embedment. Non-Darcy flow factors and constants are presented for calculating non-Darcy flow vs sand type and size between coal.
Damage to Coal Permeability During Hydraulic Fracturing
Authors: Puri R. , King G. E. , Palmer I. D. 
Published: December 2007

ABSTRACT
Coalbed methane wells are routinely fracture stimulated using gelled fluids and proppants. Surprisingly, there is no published report on the compatibility of the coals with fracturing fluids containing polymers, surfactants, biocides, friction reducers, and other chemicals. The objective of the research presented here was to understand and measure the change in coal permeability after it was brought in contact with hydraulic fracturing fluids.
The permeabilities of whole core samples of coals from San Juan and Warrior Basins were severely damaged (5-10 fold reduction) after they were exposed to gelled fracturing fluids that had been broken and filtered repeatedly. Efforts to restore coal permeability by prolonged flushing with water and HC1/HF solutions were unsuccessful. While damage to coal permeability appears to have been caused by sorption-induced swelling of the coal matrix, some plugging of the cleat system by residual gels cannot be ruled out.
Based on limited lab data, it appears that even water containing low concentrations of friction reducing polymers can cause significant damage to coal permeability. These results are alarming since extensive damage to coal permeability by gelled fluids and friction reducing polymers could negate most of the benefits of a large effective wellbore radius created during an expensive fracture stimulation. Field comparison of well productivities suggest that, in general, small low cost propped water fractures are as effective, if not more, as large high cost propped gel fractures. It is anticipated that coal permeability damage would be exacerbated in thin, low cleat porosity, high permeability coal seams.
It is recommended that every effort be made to avoid contacting coals with gelled fluids, polymers, or liquid chemicals. Furthermore, remedial workover treatment should be considered for coal wells that could have been damaged in the past by hydraulic fracture stimulation.
Efficient Algorithms for Computing the Bounded Reservoir Horizontal Well Pressure Response
Authors: Thompson L. G. , Manrique J. L. , Jelmert T. A. 
Published: December 2007

ABSTRACT
In recent years, horizontal wells have assumed an ever increasing role in the production of fluids from hydrocarbon reservoirs. While these wells significantly improve productivity in many cases, they also present difficult interpretation problems to engineers who must analyze and predict their behavior. In particular, analysis of pressure transient well test data and prediction of rate decline behavior are not straightforward. This is due to the complex system geometry; i.e., pressure and rate behavior are affected by reservoir boundaries, anisotropy, well length, well location in the reservoir, etc. Our major purpose is to present simple efficient algorithms for generating horizontal well pressure and rate responses, to facilitate analysis and prediction in these complex systems.
Analytical solutions for the pressure response for a uniform flux horizontal well in a finite anisotropic sealed rectangular box reservoir is well known and documented in several previous publications. The exact (constant rate) solution involves a product of three infinite series, which (if not treated carefully), can require a large computational effort to evaluate. The first objective of this paper is to show how the solution can be accurately evaluated over all time ranges with minimal computational effort. (In test runs on an IBM compatible 20 MHz 386DX, 12 log cycles of pressure data encompassing all flow regimes, were generated in under 9 seconds.)
Using the constant sandface rate pressure response, we show how to efficiently generate the variable sandface rate pressure response in the reservoir for both homogeneous and dual porosity systems. In this case, we work in both real and Laplace space to optimize the computational speed. As examples, we show how the method is applied to generate wellbore pressure response when wellbore storage effects are important, and to generate decline curves for constant wellbore pressure production.
Finally, using the Principle of Superposition in time, the pressure response for production at a sequence of constant rates (with or without wellbore storage effects) is generated. Buildup is included as a special case of multiple step rate production.
Use of the Borehole Television Camera and the Low-Volume Flowmeter to Identify and Measure Gas Flow in Low-Permeability Formations
Authors: Walbe K. , Collart D. 
Published: December 2007

ABSTRACT
Within many of the low permeability gas reservoirs of the world identification and measurement of gas entries is difficult due to the low volume of the flow. Also, in many areas, identification of natural fracturing is important since much of this fracturing is related to better production within the low permeability formations.
During logging operations the Borehole Television Camera (BHTV) is capable of giving a real-time observation of the wellbore by use of a colour television camera mounted on the end of the camera tool assembly. This camera transmits a picture directly to a monitor within the logging truck. Observed oil and gas entries are noted and natural fracturing can be observed. Also, with the BHTV's internal gyroscope the orientation of the observed fracturing can be recorded. Twin VHS videotape recorders record the logging run for a permanent client record.
The Low Volume/High Resolution Flowmeter (HRFM) is used in conjunction with the BHTV in both open and cased hole logging as it is capable of measuring gas flow down to a fraction of an MCF. With the HRFM, flowrate is determined by injecting a tracer gas into the gas flow1. The dilution of the tracer gas is then measured at a downstream detector. Mass flow is therefore determined by this method rather than the velocity of the gas in the wellbore as measured by conventional production spinner surveys.
Both the BHTV and the HRFM are capable of being run in vertical and horizontal open and cased holes.
Horizontal Wells: Concepts in Reservoir Evaluation
Authors: Jacobson S. J. , Fett T. H. , Singer J. M. , Ahmed U. 
Published: December 2007

ABSTRACT
The primary challenge in evaluating a horizontal well is to clearly identify what is needed and what is done with this information. The formation parameters that best define naturally fractured formations are quite different from those associated with matrix permeability reservoirs. The need for logging tools will also be different. And, the difference in the measurement geometry between the vertical and horizontal settings for each type of tool further complicates the evaluation.
This paper is comprised of four parts. The first examines current client needs in horizontal well evaluation for both the naturally fractured and matrix type reservoirs. Next, a basic view of the geometrical considerations in the transition from the vertical to the horizontal depth frame is discussed. This is followed by discussion of the measurement characteristics of the most common openhole tools as they pertain to fractured and matrix reservoirs. The paper concludes with several interpretation case examples.