bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recovery of Coalbed Methane by Gas Injection
Authors: Zhu Jichun , Jessen Kristian , Kovscek Anthony R. , Orr Franklin M. 
Published: December 2007

Abstract
Injection of either carbon dioxide (CO2) or nitrogen (N2) can serve as an effective method for enhanced recovery of coalbed methane. In this paper, we provide new analytical solutions for flow of ternary gas mixtures. The adsorption/desorption of the components to/from the coalbed surface is approximated by an extended Langmuir isotherm, and the gas phase behavior is predicted by the Peng-Robinson EOS. Langmuir isotherm coefficients are used that represent a moist Fruitland coal sample from the San Juan Basin of Colorado. In these calculations, mobile liquid is not considered. Given constant initial and injection compositions, a self-similar solution that consists of continuous waves and shocks is found. Mixtures of CH4, CO2, and N2 are used to represent coalbed and injection gases. We provide examples for systems in which the initial gas has a high CH4 content, and binary mixtures of CO2 and N2 are injected. Injection of N2-CO2 mixtures rich in N2 leads to relatively fast initial recovery of CH4. Injection of mixtures rich in CO2 gives slower initial recovery, increases breakthrough time and decreases the injectant needed to sweep out the coalbed. The solutions presented indicate that a coalbed can be used to separate N2 and CO2 chromatographically at the same time CBM is recovered.
Cavitation for Effective Well Cleaning
Authors: Bakker Tom W. , Ivannikov Vladimir I. 
Published: December 2007

Abstract
Active cavitation is novel, powerful, coiled tubing or workstring conveyed technology. Cavitation is the process of creating transient vapor filled cavities in a fluid at ambient fluid pressures exceeding the vapour pressure in the cavities. Implosions of such cavities are known to cause damage to ships propellers and pump impellors, however the effects can also be usefully applied for many purposes, including applications in the well construction and well servicing disciplines.
Commonly known cavitation occurs in low-pressure areas when a fluid flows around an obstruction or past the surface of an oscillating body; this type of cavitation is referred to as passive cavitation.
The particular technology described in this paper is referred to as ‘active’ cavitation. This is a method using liquid hammer enhancement to create vapor bubbles at much higher ambient pressures than previously possible. The vapor cavities at low pressure points created at high ambient pressure implode violently and decay into smaller bubbles thus significantly extending the life and extent of the low-pressure zone or ‘cavitation flare’ and enhancing the action of the jetstream flowing from the cavitator. A particular value of cavitation is that it produces a twofold effect, i.e. a combination of suction effects in the decaying cavitation flare and shock wave effects that reach much further away from the cavitation generating tool.
Active cavitation can for instance be employed to improve the hole making process, clean reservoir rock or remove scale and deposits from well completion equipment. Thus, use of cavitators allows intensifying rock fragmentation and bit cleaning. During field trials in Russia it was demonstrated that drill rates can be increased by up to 40% and bit life can be extended by up to 25% compared to the performance of previously applied bits. When using cavitators for fraccing and decolmatation (removal of fine plugging material) production or injection improvement of 1.5 – 3 times are commonly being observed. Cavitation is also very effective in cleaning tubes or plugged screens in water, oil or gas wells because it effects most commonly occurring deposits, including deposits that are insoluble in acid.
Establishing Inflow Performance Relationship (IPR) for Gas Condensate Wells
Authors: Jokhio Sarfraz A. , Tiab Djebbar 
Published: December 2007

Abstract
A new simple method of establishing Inflow Performance Relationship for gas condensate wells is proposed. The proposed method uses transient pressure test data to estimate effective permeability as function of pressure and then uses it to convert production BHFP data into pseudopressure to establish well performance. Requirement of relative permeability as function of saturation thus has been completely eliminated. Effective permeability of either phase can be used to predict the production of second phase. A scheme has also been devised to estimate the effective permeability using well testing mathematical models available in literature.
Also mathematical models of well deliverability loss due to condensate deposition when dew point pressure is reached, and deliverability gain due to condensate mobility when P* is reached have been developed. Pseudopressure curves for both oil and gas phase have been developed for quick conversion of pressure data into pseudopressure. Relative permeability curves if available can also be used, however, the knowledge of saturation has to be known at all the stages of the depletion to be able to use them.
Gas condensate reservoirs are primarily gas reservoirs. As the pressure declines with depletion, reservoir conditions of pressure may go below dew point and liquid begins to buildup. Such reservoirs may go under liquid buildup without showing any trace of liquid production. Sudden well deliverability loss and very high skin factor estimates from pressure tests are strong indicators of liquid buildup. PVT characteristics like phase diagram help identify the problem too. As the critical conditions are reached such reservoirs become two phase in nature.
Finally, a field example is analyzed to show the use of new method developed and a step-by-step procedure is used to establish the well performance. Small operators, Independents, will benefit from this method at the most, since data acquisition like relative permeability curves require the laboratory experiments on cores, an expensive procedure.
Development Modeling of the Saih Nihayda Gas-Condensate Field
Authors: Azhar Al-Kindi , Langedijk Robert 
Published: December 2007

Abstract
As the demand for natural Gas in the Sultanate Of Oman rises both internally through domestic and industrial growth, and externally through the LNG export, the development of more gas fields becomes a necessity. Being centrally located, close to existing central processing plant, and with considerable volume in place, the rich gas-condensate Saih Nihayda field, is seen as the next candidate for development.
A full field model was built for Saih Nihayda to study uncertainties and investigate the optimum development option for the three deep stacked reservoirs. The hydrostatically pressured Barik sandstone being the shallowest and the most complex is a gas-condensate reservoir, whereas the Miqrat and the Amin sandstone are both over-pressured dry gas reservoirs.
This paper details an integrated approach followed in assessing the impact of various uncertainties on development options. It highlights the modelling process from seismic inversion to demand driven forecasting and economic assessment. Special attention was paid to gas-condensate specific phenomena such as condensate impairment.
Beside the high technical demand associated with understanding the physical behaviours of gas-condensate reservoirs, the variability in static and dynamic characteristics of the three Saih Nihayda sandstone reservoirs offers commercially challenging development options.
Comparison studies included commingled reservoir production versus non-commingled and the impact of hydraulic fracturing versus non-fracturing on reduction in total well numbers and acceleration of early condensate. The paper touches on the benefit of variability in characteristics coupled with economical and technical viability on considering exotic development options like dump-flooding and gas recycling.
X-ray Computed Tomography Observation of Methane Hydrate Dissociation
Authors: Tomutsa Liviu , Freifeld Barry , Kneafsey Timothy J. , Stern Laura A. 
Published: December 2007

Abstract
Deposits of naturally occurring methane hydrate have been identified in permafrost and deep oceanic environments with global reserves estimated to be twice the total amount of energy stored in fossil fuels. The fundamental behavior of methane hydrate in natural formations, while poorly understood, is of critical importance if the economic recovery of methane from hydrates is to be accomplished. In this study, computed X-ray tomography (CT) scanning is used to image an advancing dissociation front in a heterogeneous gas hydrate/sand sample at 0.1 MPa. The cylindrical methane hydrate and sand aggregate, 2.54 cm in diameter and 6.3 cm long, was contained in a PVC sample holder that was insulated on all but one end. At the uninsulated end, the dissociated gas was captured and the volume of gas monitored. The sample was initially imaged axially using X-ray CT scanning within the methane hydrate stability zone by keeping the sample temperature at 77°K. Subsequently, as the sample warmed through the methane hydrate dissociation point at 194°K and room pressure, gas was produced and the temperature at the bottom of the sample plug was monitored while CT images were acquired. The experiment showed that CT imaging can resolve the reduction in density (as seen by a reduction in beam attenuation) of the hydrate/sand aggregate due to the dissociation of methane hydrate. In addition, a comparison of CT images with gas flow and temperature measurements reveals that the CT scanner is able to resolve accurately and spatially the advancing dissociation front. Future experiments designed to better understand the thermodynamics of hydrate dissociation are planned to take advantage of the temporal and spatial resolution that the CT scanner provides.
Trucking of Compressed Natural Gas (CNG) from the Naturally Fractured Galt Field in the Gaspe Area of Quebec
Authors: Aguilera R. , Lavoie J. Y. 
Published: December 2007

Abstract
Based on a 427-km seismic survey run in Gaspe in the early 1980's, well Galt # 1 was drilled to a depth of 2500 m in 1983. Several Devonian DSTs indicated the presence of 46-degree API oil in the Indian Cove formation between 993 and 1309 mKB, and gas in the Forillon formation between 2245 and 2353 mKB.
The well was not considered economic at the time and was abandoned using various cement plugs. Subsequent evaluation of the log and DST data indicated that the naturally fractured Forillon limestone had been heavily damaged during drilling operations.
The well was re-entered in September 1993 and following an acid job tested at approximately 1 m3/day of oil from the Indian Cove formation. The well was next drilled out to the Forillon formation in June 1994. It flowed at approximately 6,400 m3/day of gas during the extended flow period; however, gas rates in excess of 56,000 m3/day were recorded during the isochronal test. Due to the lack of pipeline infrastructure, the gas is being trucked to a copper smelter plant operated by Noranda at Murdochville. This replaces the propane previously used at the smelter.
This paper discusses the geology of the area, the log and DST data, the compressed natural gas (CNG) system used for trucking the gas and the economics of the project.
Matching Technical Solutions to the Lifecycle Phase is the Key to Developing a CBM Prospect
Authors: Blauch Matthew E. , Weida Dana , Mullen Mike , McDaniel B. W. 
Published: December 2007

Abstract
The early stages of a coalbed methane (CBM) project development often require more extensive use of currently available technologies than can be economically justified when approached from a conventional oil and gas drilling focus. As a result, key evaluation tools and technologies are either omitted or not considered before significant decisions are made regarding viability of a CBM play. Understanding that the various lifecycle phases will each affect different objectives and decision points is important. Following site acquisition and estimating basic drilling costs, at least five lifecycle phases can be identified: (1) Regional Resource Reconnaissance, (2) Local Asset Evaluation, (3) Early Development, (4) Mature Development; and (5) Declining Production.
A systematic review of current and recently developed enabling technologies is presented in the context of their potential use and applicability. Environmental risk and other constraints that can impact development vary globally, as do economics and production forecasting. New and emerging chemical technologies, as well as hydraulic fracturing refinements, play key roles in various lifecycle phases and decision making to identify successful CBM development projects as early as possible. The paper presents strategies that can reduce development phase failure risk and help predict or rank production potential. Economic constraints usually become more restrictive as the lifecycle moves to Phase 4 and beyond, but key information needed to enter Phase 4 is often overlooked. Examples of this scenario are presented from a global perspective.
Globally, new and existing technologies combined with dynamic gas and electricity markets are changing the nature of CBM development opportunities. More accurate and timely go/no-go information needs to be used in the decision making process. Converting development opportunities to develop-ment successes involves integrating planning and evaluation methods, using targeted development technologies in the proper phase, and managing risk.
Correlations to Determine Retrograde Dew Pressure and C7+ Percentage of Gas Condensate Reservoirs on basis of Production Test Data of Eastern Venezuelan Fields
Authors: Marruffo Ilsis , Maita Jose , Him Jesus , Rojas Gonzalo 
Published: December 2007

Abstract
In this paper are presented new correlations to determine the dew point pressure and C7+ content of gas condensate reservoirs, based on production fields parameters usually available. To develop these correlations it were collected 146 PVT analyses of Venezuela (Anaco) fields: San Joaquin: 42; Santa Rosa: 26; El Roble: 16; Guario: 4; Santa Ana: 3; El Toco: 3; Zapatos: 15; Mata-R: 15; Aguasay: 13; La Ceibita: 5; Carisito: 4.
The PVT results were validated through consistence tests: mathematical recombination and mass balance. After these steps an statistical analysis of the variables was done.
For this, statistical methods were used and they were focused on multiple no linear regressions.
The correlations's accuracy was the following: dew point pressure showed 5.74 % of average error with a correlation coefficient of 0.82 based on 80 PVT's data, the first C7+ content correlation showed 9.59 % of average error with a correlation coefficient of 0.98 based on 81 PVT's data, the second C7+ content correlation showed 7.85 % of average error with a correlation coefficient of 0.99 based on 90 PVT's data.
The new retrograde dew point correlation obtained improves the Nemeth and Kennedy's (10) that forecast dew points with 9.69 % of average error when it is applied on 54 Anaco's PVT analyses which had all the compositional information that it requires; with the new dew point correlation the average error was 5 % for the same data. These new correlations allow to improve the characterization and exploitation plans of gas condensate reservoirs without PVT information.
Why Plot the Equivalent Time Derivative on Shut-in Time Coordinates?
Authors: Anderson David , Jordan Colin Lyle , Mattar Louis 
Published: December 2007

Abstract
The (semilog) derivative of pressure data from oil and gas wells is a widely accepted and highly useful tool for reservoir characterization. For buildup pressure data, this derivative is calculated with respect to equivalent time. It is generally assumed that since this derivative is obtained using equivalent time, it should be plotted on a coordinate axis that uses equivalent time. However, in the presence of boundaries, this style of plotting distorts the shape of the derivative during late-time, to the point where it bears very little resemblance to the original shape of the drawdown derivative. Moreover, the shape of the buildup derivative is strongly affected by the duration of the preceding drawdown.
This paper investigates the shape of the equivalent-time-derivative when plotted against both equivalent time and real time (shut-in time) coordinates. Using computer generated models, it shows that a plot based on real time produces a buildup derivative response that is much closer in shape to the drawdown derivative, thus resulting in more accurate diagnosis of reservoir characteristics. This was true regardless of reservoir type, geometry or producing time. The advantages of using real time as a plotting coordinate are, a more readable diagnostic plot and a more easily recognized shape because of its similarity to the drawdown.
Our research extends the work of Spivey (1999). This study investigated numerous reservoir types including homogeneous with boundaries, composite, fractured and dual porosity, and it also covered a wide practical range of producing times.
Custom Recirculation ESP System in 7-in. Casing Increases Indian Basin Gas Well Production
Authors: Gaddis R. D. , Knight J. W. , Lisenbee J. T. 
Published: December 2007

Abstract
Recirculation electric submersible pump (ESP) systems have been successfully deployed below well perforations to avoid gas interference in the pump and to maximize well drawdown. Most of these units consisted of ESP equipment designed for 5.5-inch well casing and included a patented system of custom-built flat recirculation tubing due to space considerations.
The operator's previous attempts at de-watering potentially high rate gas wells in order to increase overall gas production had consisted of shrouded 4.50-inch outer diameter (OD) motor ESP systems set below the perforations. The motor was re-rated above standard nameplate horsepower due to the hydraulic requirement necessary to lift approximately 4500 bwpd from a depth of ± 7500 ft. true vertical depth. The amount of water production with the shrouded unit, and hence, gas production, was limited because of motor horsepower limitations.
This paper describes the first known applications of a customized "flat-tube" style recirculation ESP unit consisting of equipment designed for 7-inch casing. A benefit of this development was to increase available motor horsepower. Results of these installations range from increased water production, and hence, increased oil and gas production, to increased run times and lower power and equipment lease costs for the operator.
The system represents a successful and significant extension of existing recirculation pump technology. Equipment description and economic and operational benefits are presented for two wells.
Novel Surveillance Helps Operators Track Damage
Authors: Brown Kenneth G. , Sawyer Walter K. 
Published: December 2007

Abstract
As part of an ongoing study sponsored by the Gas Technology Institute, new technology has been developed that provides storage operators with a cost effective method to frequently monitor wellbore damage with reasonable accuracy. Two procedures were developed and tested, the Sawyer-Brown Method (SB Method) and the Minute-Rise Deconvolution Method (MRD Method). These procedures are inexpensive, since no service company personnel or down-hole equipment is required. Consequently, the wells can be tested at much more frequent intervals than is typical of current testing methods.
The theoretical basis of each method is developed. The successful application of the SB Method is demonstrated using conventional deliverability test data and verified using multiple rate pressure transient tests in which bottom hole pressure gauges were used. The theoretical basis of the MRD Method is validated using simulated data. Difficulties encountered in the practical application of the MRD Method are presented and discussed. Areas of additional work are identified and guidelines for the implementation of these methods are presented.
Integrated Multidiscipline Approach Lead To A Recent Success In Naturally Fractured Reservoir - The Macueta Experience.
Authors: Girardi A. , Cohen M. , Kozlowski E. 
Published: December 2007

Abstract
The Macueta is a gas field located in the Acambuco Area, Tarija Basin, Northwest Argentina. This area is owned by the Acambuco Consortium: Pan American Energy (operator, 52%), Shell (22.5%), Repsol-YPF (22.5%), Apco (1.5%) and NorthWest (1.5%). The reservoir is formed by tight naturally fractured quarzitic sandstones of Devonian age (Huamampampa and Icla Formations), trapped in a narrow and elongated anticline within the subandean region.
Since the early 80's, four drilling initiatives, including vertical and horizontal wells, showed moderate to no success at all (AOF = 3 MMscfd- 14 MMscfd).
A new approach, using modern well testing and logging tools, was performed. This approach, including a careful study of the fracture system, in situ stress analysis and fracture production characterization, turned the view and triggered the field development.
The key to success was the identification, through selective zone well testing, of a zone far from the wellbore with high permeability, and its association with better fracture development in the crestal zone of the structure. This finding helped to understand the production mechanism of the reservoir.
This study is supported by acoustic image logs, production logs and well tests taken in Mac.x-1001bis, a former vertical well.
In this well, a succesful drilling reentry operation was executed after planning a 1150 ft long horizontal well trajectory with improved chances of success by maximizing fracture intersection.
The Mac.x-1001bis reentry well tested 36 MMscfd of gas and it has an absolute open flow (AOF) of 144 MMscfd. This increase of productivity, up to 40 times compared with the former wells, proves the convenience of horizontal technology in naturally fractured environments when it is carefully planned and executed.
This well sets a record in the basin for the Icla Fm. and opens new expectations and possibilities for the development of this type of reservoirs.
Cased Hole Formation Resistivity Applications in Alaska
Authors: Hupp Douglas , Kidd Gordon , Harris Jeff , Frankforter Matt 
Published: December 2007

Abstract
This paper describes the theory of cased hole formation resistivity measurements and presents examples demonstrating the diversity of their use. Resistivity behind casing has many applications, from evaluating formations in new wells to monitoring water influx and bypassed hydrocarbons in producing wells. These robust deep-resistivity measurements can be combined with data from traditional cased hole and openhole evaluation tools to provide a comprehensive formation evaluation from behind casing.
Example A highlights the use of these measurements in the successful completion of a new Cook Inlet offshore well. Traditional openhole logs were not obtained because of hole conditions and the borehole environment, which also limited traditional cased hole evaluation techniques such as sigma and carbon-oxygen logging. The new resistivity measurements were instrumental to the successful completion of this well as an oil producer with low water cut.
Examples B and C, from wells in a mature field, demonstrate the use of the measurements to identify water influx and encroachment, which is vital for reservoir monitoring. Both wells produced water from high-permeability thief zones, which prompted profile modification to limit water production and enhance off-take from zones with lower permeability. The new cased hole resistivity measurements provided valuable data, not available from traditional production logs, to assess sweep efficiency, which will be used to guide recompletion or sidetrack decisions.