bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas Transportation: Present and Future
Authors: Rajnauth J. , Ayeni K. , Barrufet M. 
Published: June 2008

Abstract
Natural gas is a versatile form of non-polluting fuel. With just over a dozen nations accounting for 84% of the world-wide production, access to natural gas has become a significant factor in international economics and politics. The major difficulty in the use of natural gas is transportation and storage because of its low density. Despite this, natural gas production has seen tremendous growth over the years. This has been due to large amount of natural gas reserves, the wide variety of uses of natural gas and carbon dioxide emissions from natural gas energy generation are far less.
In the past, the natural gas recovered in the course of producing petroleum could not be profitably sold, and was simply flared. This wasteful practice is now illegal in many countries. The most common method for transporting natural gas was high pressure in underground pipelines. Additionally, countries now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future. In many cases the gas is now re-injected back into the formation for later recovery. Transportation is now a very important and key role in the supply chain for natural gas and the big challenge is to transport gas to markets at the lowest cost without too much environmental risks. Now re-gasification at the market is important when selecting the mode of transportation of natural gas.
This paper reviews, analyzes and provide insight to present and future gas transportation methods. These options of transporting gas from oil and gas field to markets include pipelines, liquefied natural gas, compressed natural gas, gas to solids (hydrate), gas to liquids, gas to wire and other gas to commodity methods. The paper provides an overview of the challenges facing present transportation modes, and discussion on possibilities for improvement via new technology or new gas transport options. Another focus of the paper is to compare and highlight some critical factors affecting the different means of transportation of natural gas. These include economics, markets, gas concentrations, environmental risks and re-gasification issues.
New Semi-Analytical Solutions for Multilayer Reservoirs
Authors: Lolon E. P. , Archer R. A. , Ilk D. , Blasingame T. A. 
Published: June 2008

Abstract
This paper presents the development, validation, and application of new approximate (semi-analytical) solutions for the wellbore pressure and fractional flowrate responses of commingled layered reservoirs — without interlayer cross/low (crossflow is only permitted in the wellbore, not in the reservoir). These formulations use "basis" pressure drop relations for each layer as a mechanism to create multilayer solutions in the Laplace domain — and due to the choice of these basis relations; the formulation can be analytically inverted into the real domain. This process provides a direct (albeit approximate) solution for multilayer reservoir systems. The basis relations include a "constant" pressure case and "linear" pressure case. In addition to these methods, we also provide a "Total Pressure/Rate Averaging" (TPRA) formulation which is used to provide an average rate and pressure response for each layer.
These semi-analytical solutions can be used to construct well test or production profiles in a simple computational environment (e.g., a spreadsheet). These solutions can also be used to diagnose well test and production data in terms of layered reservoir behavior. The "linear" pressure case (non-zero intercept) gives the best performance — however, from a practical standpoint, the algebra involved limits this approach to 2-layer reservoir case. The TPRA formulation is very consistent, but not as accurate as the other solutions — however; the TPRA formulation is easily be extended to n-layers.
Simplifying Gas Production Modeling
Authors: Jordan Colin L. , Jackson Robert , Smith Cooper 
Published: June 2008

Abstract
This paper presents a simple, but reliable, method for predicting the performance of multiple gas wells in complex reservoir shapes. Using an approximation of the traditional "image well" method, pressure and production profiles can be generated for arbitrary shaped reservoirs, with internal boundaries and similar heterogeneity, as well as multiple well completions. The procedure will allow for modeling and analysis, as well as forecasting of complex operating conditions including varying rate and flowing pressure schedules (including shut-in) for conventional and unconventional gas systems without the need of advanced engineering mathematics or computational libraries.
The approach overcomes many limitations of conventional analytical methods (i.e. single well solutions or limited reservoir shapes) which are generally unsuitable for multi-well planning, in-fill drilling, or full field development. But, it also allows for petroleum engineers, without numerical simulation resources or skills, to perform field wide evaluations on reservoirs and wells with a variety of operating conditions. A number of computational and quality issues are addressed including Laplace space inversion methods; addition of wellbore storage and skin (at wellbore and observation points); incorporation of absorbed gas for unconventional gas systems; pressure dependant fluid properties; reservoir heterogeneity; and rate forecasting. The methodology is validated by comparison to both analytical solutions and commercial numerical tools.
In short, a new mathematical approach for production modeling and forecasting has been introduced. Mathematical adaptations for reservoir heterogeneity, complex reservoir shapes, multiple completions and rate forecasting are discussed. Adaptations and applications for both conventional and unconventional gas (including coal and shale gas) are demonstrated. Finally, a simple solution process is presented for quick and easy implementation in MS Excel or other common tools.
Volumes and Areas of Pendular Rings With Non-Zero Contact Angle in Tight Gas Sands Dominated by Contractional Fractures and Slot Porosity
Authors: Aguilera Roberto 
Published: June 2008

Abstract
Contractional natural fractures and slot porosity play and will continue to play an important role in commercial gas production from tight sands. The process that leads to these types of porosities starts with deposition of sand grains. As the grains get progressively buried inelastically the net stress increases continuously. Eventually the sand grains reach their maximum depth of burial and at this stage the vast majority of the porosity and permeability has been destroyed. Uplift leads to a cooling effect and thermo-elastic stresses that create contractional fractures and slot porosity.
Throughout these processes the sand grains get deformed and as a result there are continuous variations in volumes and areas of pendular rings, which lead to variations in porosities, permeabilities and water saturations.
This paper discusses models that can be used for estimating these variations for zero and non-zero contact angles in tight gas sands.
The subject is significant because historically oil and gas companies have gone, rightly, after tectonic fractures associated with folding and faulting in tight gas sands. The present work discusses a different possibility as the contractional fractures discussed above are not restricted to areas dominated by major tectonic events.
One-Trip Multistage Completion Technology for Unconventional Gas Formations
Authors: Watson Don R. , Durst Doug G. , Harris Travis , Contreras Jesus D. 
Published: June 2008

Abstract
Cost-effective development of unconventional gas resources depends upon strategic application of advancing technologies. By employing efficient fracturing techniques with an appropriate multi-stage fracturing completion, operators can achieve higher initial gas rates, increased recovery rates and reduced completion costs. The completion process employs a single-trip multi-stage completion system which is driving the cost-effective exploitation of difficult reservoirs. Discussion will center on planning and execution strategies followed by some case history results and lessons learned. The introduction of a new feature to improve operational efficiency and future system improvements will be addressed.
The planning stage considers key factors associated with reserve estimates, selection of number of fractures, production behavior analysis, production forecast analysis, risk analysis, fracture design, and economic evaluation. The installation stage considers equipment and operational issues such as quantity and spacing of packers and sleeves. The completion stage involves techniques and procedures of the fracturing process. These planning and execution strategies achieve mechanical, volumetric and economic success, established by the efficiency of each fracture and total gas production rate when compared to initial evaluations.
The one-trip multi-stage fracturing completion process reduces rig time and cost for hydraulic fracturing services, accelerates production and improves reservoir drainage. When coupled with effective fracturing strategies and best practice procedures, the system provides improved production from unconventional gas formations.
Maximizing Energy at Coalface for Coalbed Methane Fracturing Operations
Authors: Mahdi Abbas W.A. , Yu Micheal , Pipchuk Douglas A. , Wasson Craig , Nguy Jim , Kathol Nathan Lawrence 
Published: June 2008

Abstract
Nitrogen coiled tubing fracturing is the predominant method for completing and stimulating dry coalbed methane (CBM) formations, such as the Horseshoe Canyon in the Western Canadian Sedimentary basin. A typical well has an average of 20 pay zones that are stimulated individually.
The coal cleats are fractured by pumping nitrogen at high rates through coiled tubing (CT) into perforations isolated by straddle assembly. Currently energy that can be delivered to the coalface of these dry CBM wells has been limited by the friction pressure through (CT). Efforts to increase the energy have involved increasing CT size and increasing surface horsepower. Economics and logistics practically limit the pipe size to 2 7/8 in. for deeper wells and 3¼ in. for shallow wells using CT fracturing technique.
This paper discusses the development of a technique which initially eliminates the CT friction limits on transferring energy to coalface. A large-volume pressure pulse is released downhole during the fracturing process to create an order of magnitude change in available energy at the fracture face, compared to current dynamic fracturing processes. The additional energy is dissipated by increasing the surface cleat area exposed. The development of the technique and field tests results will be discussed.

Introduction
The Horseshoe canyon dry coal formations have been commercially exploited since late 2000. From the beginning it was clear the Horseshoe Canyon CBM play was a unique CBM play, it is set apart by consisting of a dry under pressured coal. The coal therefore does not require dewatering before production. The coal consists of multiple thin seams, ranging from 10 - 30 seams per well. The coal seam thickness ranges lies between 0.1 and 2.5 meters. (Fig 1 - Horseshoe Canyon CBM log)
The production rates from these CBM wells dictates that a efficient drilling and completion model be adopted in order to be economic. The current model that is utilized is the wells are drilled with coiled tubing drilling rigs, cased and cemented. Wireline perforating crews are then dispatched to perforate the zones of interest in a rig less operation. The individual coal seams are then stimulated via the injection of dry nitrogen at high rates through a coiled tubing reel that is equipped with a fracturing isolation tool. The dry coal has not responded well to any other form of stimulation. The lack of success of more traditional stimulation methods is deemed to be damage to the dry under pressured coal seams.
Use of Bandra Formation Lean Gas as Fuel Gas at Heera Processing Complex (Offshore)
Authors: Gupta Anil Kumar , Asija Narendra 
Published: June 2008

Abstract
HEERA, one of the most promising hydrocarbon producing fields in Mumbai offshore; produces oil and gas from multilayered pay zones ranging from depth of 700 meters to 1500 meters. Bandra Formation, the uppermost strata of reservoir is a Miocene structure. This is the youngest pay zone in the Cenozoic carbonates of Mumbai Offshore basin comprising of limestone with shale bands at a depth of about 700 meters sub-sea bearing lean gas with 96+ percent of C1. Heera Offshore Processing Complex presently uses 2, 50,000 SCMD of rich gas for internal consumption mainly in turbine generators and Process Gas Compressor drivers. Process complex delivers gas to three users i.e. Gas Lift Wells at 80 kg/cm2, End Consumer at 56 kg/cm2 and Internal Consumption at 27 kg/cm2. Presently, fuel gas is tapped from Process Gas Compressor discharge at 80 kg/cm2. This gas has about 28% of C2+ component and good source for Value Added Products like C2/C3, LPG, Naphtha, etc. Study reveals that Bandra gas shall be ideally suited as fuel gas. Rich gas when replaced by lean Bandra gas as fuel gas will in turn add in to the Value Added Products (VAP) extraction. Around 1.0 MMSCMD gas production is expected thru upcoming three gas producers on HG platform in Bandra formation lasting for a period of 15 years.
The study suggests maximum utilization of Bandra gas as fuel gas in phased manner depending on the available formation pressure. Study also infers a) Optimization of the compressor utilization depending on the end pressure requirement by way of dedicating one compressor exclusively for compressing lean Bandra Gas at 56 kg/cm2, b) Split the two trains of Gas Dehydration Unit and operate them at 80 kg/cm2 and 56 kg/cm2 pressures respectively. Thus saving in compression energy of 960 KW per compressor, c) Sourcing fuel gas from Bandra formation shall reduce collective emissions of Green House Gases (GHG), mainly CO2, by an average of 7.28 percent compared to the present emission using rich gas, d) Rich gas thus added in the gas to consumers will add quantities of VAP (C2/C3: 50 TPD, LPG: 50 TPD and Naphtha: 8 TPD) extracted at downstream end.
The above study has optimized compression, dehydration facilities in terms of energy conservation, reduction of GHG emission and generation of VAP. Recommendations of the study are currently in the process of implementation.
Tight Gas Production Performance Using Decline Curves
Authors: Kupchenko C. L. , Gault B. W. , Mattar L. 
Published: June 2008

Abstract
Traditional ("Arps") decline analysis is the most common reservoir engineering tool used for production performance forecasting. It has several advantages over other techniques in that it is simple to use, requires minimal data and is well understood by the industry. Currently, however, these methods are being misused in unconventional applications, such as tight gas.
Production perfomance from tight gas reservoirs is characterized by steep initial decline rates and long periods of transient flow. If decline analysis is performed using this transient production data, the main assumption of boundary dominated flow (BDF) is violated and inaccurate forecasts may result. The goal of this work is to understand the behaviour of tight gas reservoirs during transient flow so that the familiar Arps method may be applied. The effects of different tight gas production responses (bilinear, linear, pseudo-radial, boundary dominated) are investigated. Finally, a methodology for applying traditional decline curve analysis to tight gas, with reference to long term transient flow, is presented.
Measurement of Relative Permeability of Coal: Approaches and Limitations
Authors: Ham Y. , Kantzas A. 
Published: June 2008

ABSTRACT
A number of laboratory studies on coalbed methane (CBM) have provided data for the relative permeability of coal to gas and water, which are needed to analyze CBM reservoirs, particularly in numerical simulation.
The relative permeability curves of coal to gas and water are determined using the two methods used in the petroleum reservoir engineering, namely, the steady or unsteady state displacement methods. In most cases, the unsteady state displacement method is used because this method is relatively fast to carry out. In this method, the non-wetting fluid is displaced by the wetting fluid, and the effluent production and pressure history are used to back out the relative permeability of coal to gas and water.
One of the problems encountered in the displacement methods is the question of coal wettability. Many researchers studying this area have considered that coal is water-wet. However, it is a well-known fact that a large amount as much as 95% of methane is adsorbed on the internal surface of coal matrix. Therefore, coal could be regarded at least as initially gas-wet. The wettability of coal will depend on the flow characteristics of coal, that is, whether methane flows in the matrix. This paper investigates a number of wettability of coal scenarios and discusses the approaches used by various investigators, for instance, pre-heating the coal sample before any testing, and using a non-adsorbable gas, pointing out their limitations from the viewpoint of CBM reservoir simulation. The likely dependence of relative permeability of coal on flow pressure is also addressed.
Modified Flow After Flow Test To Predict Deliverability of Gas Wells With Turbulence
Authors: Kisko Sarah , Liao Shu Ping (Sandy) , Mattar Louis 
Published: June 2008

Abstract
This paper consists of two parts. The first part establishes the presence of turbulence in low pressure gas reservoirs even at relatively low rates. It is shown that it would be beneficial for these low pressure reservoirs to be tested using multiple rates to establish the level of turbulence. The second part describes a new type of flow test, which is a modified version of the traditional flow after flow test. The method of analysis of this proposed test requires the use of commonly available well testing software, and has been verified using synthetic data.
Pressure-Transient Test Design in Dual-Porosity Tight Gas Formations
Authors: Shahamat Mohammad Sadeq , Aguilera Roberto 
Published: June 2008

Abstract
The existence of natural fractures and their effects on the wellbore storage vanishing time and the onset of the outer boundary in a tight gas reservoir are examined. The so called pre- and post-fracture test design is used for both linear and radial flow type to investigate the effect of different values of ω and λf on the time needed for the wellbore storage to disappear and for the outer boundary to be reached.
It was found that for a constant hydraulic fracture conductivity, decreasing the ω value causes the wellbore storage to vanish earlier. Conversely, increasing the value of λf, with omega constant, causes the wellbore storage to vanish earlier. These changes have no effect on the time to reach outer boundary, which can be sealed or at constant pressure.
Commercial production from a tight gas reservoir seems to be a function of effectiveness of the natural fractures, and the hydraulic fractures. Applying the concept of dual porosity behaviour to a tight gas reservoir, as opposed to the single porosity behaviour that is considered by several other researchers, seems to be a promising idea for better understanding of these reservoirs.
Low-Volume Pumping Systems: Moving Gallons to Produce Thousands
Authors: Poythress Mike , Rowlan Lynn 
Published: June 2008

Abstract
In recent times, a continuous fiberglass rod pumping system has been designed for producing low volumes of fluid from gas wells that are loaded up with water. This system utilizes an efficient, low horsepower pumping unit, which operates on a ½ horsepower, solar powered DC electric motor. A conventional insert type rod pump is utilized so that pump changes do not require a work over rig, only the use of a spool trailer.
Other than using solar power this system is installed in two other configurations: 1) Hybrid – using available electricity and 2) Just the continuous fiberglass rod under a conventional beam pumping unit. In any configuration the goal is to minimize friction losses, so a small motor can power the system. Small diameter plunger limits both the fluid load lifted by the rods and limits the amount of fluid volume that can be produced to the surface, but only a few barrels per day of water can lead to liquid loading and killing flow from a gas well. Dynamometer and fluid level measurements will be presented to show the performance of several of the existing systems – Solar and Hybrid. Depth limitations for the ½″ diameter fiberglass rod will be discussed. Small diameter pump, small pumping unit size and light weight continuous rods allow the operator to use less than 1 hp motor to power the system.
Prevalence of and risk factors for hip dysplasia and cranial cruciate ligament deficiency in dogs
Authors: Witsberger Tige H. , Villamil J. Armando , Schultz Loren G. , Hahn Allen W. , Cook James L. 
Published: June 2008

Abstract
Objective—To evaluate prevalence of and risk factors for hip dysplasia (HD) and cranial cruciate ligament deficiency (CCLD) in dogs and determine change in prevalence over time.
Design—Cross-sectional study.
Animals—1,243,681 dogs for which information was reported to the Veterinary Medical Database between 1964 and 2003.
Procedures—Information on breed, sex, and age was collected, and prevalences and odds ratios were calculated.
Results—Castrated male dogs were significantly more likely than other dogs to have HD (odds ratio [OR], 1.21), and castrated male (OR, 1.68) and spayed female (OR, 2.35) dogs were significantly more likely to have CCLD. Dogs up to 4 years old were significantly more likely to have HD (OR for dogs 2 months to 1 year old, 1.22; OR for dogs > 1 to 4 years old, 1.48), whereas dogs > 4 years old were significantly more likely to have CCLD (OR for dogs > 4 to 7 years old, 1.82; OR for dogs > 7 years old, 1.48). In general, large- and giant-breed dogs were more likely than other dogs to have HD, CCLD, or both. Prevalences of HD and CCLD increased significantly over the 4 decades for which data were examined.
Conclusions and Clinical Relevance—Results suggested that sex, age, and breed were risk factors for HD, CCLD, or both in dogs and that prevalences of HD and CCLD have increased over time.