bluuebunny/crossref_metadata_2025 huggingface dataset:
Capillary Wicking in Gas Wells
Authors: Mahadevan Jagannathan , Sharma Mukul M. , Yortsos Yannis C.
Published: January 2008

Gas expansion near the wellbore during production causes the evaporation of connate water. When the reservoir permeability is low, capillarity is controlling, causing liquid movement to the near-wellbore region, where drying rates are higher. In tight-gas sands or in shale gas formations, where capillarity is high, the gas production itself can cause depletion of the water saturation below residual values because of such evaporation.

In this work, we present a study of the fundamental processes involved during the flow of a gas in a liquid-saturated porous medium. We have modeled evaporation by accounting for the capillary driven film flow, or "wicking," of saline liquid to the wellbore or the near-fracture region and the effect of gas expansion. It is shown that, for gas reservoirs with connate water saturation, large pressure drawdowns lead to a drying front that develops at the formation face and propagates into the reservoir. When pressure drops are lower, water rapidly redistributes because of capillarity-induced movement of liquid from high- to low-saturation regions. This phase redistribution causes higher drying rates near the wellbore.

The results show, for the first time, the effect of both capillarity-induced film flow and gas compressibility on the rate of drying in gas wells. The model can be used to help maximize gas production under conditions such as water blocking by optimizing the operating conditions. Additionally, it can be used to obtain a better understanding of the impact of capillarity on evaporation and consequent processes, such as salt precipitation.
Brine Viscosity Correlation with Temperature Using the Vogel-Tammann-Fulcher (VTF) Equation
Authors: Civan Faruk
Published: January 2008

Theoretically meaningful correlation of the viscosity of typical brines with temperature and dissolved salt concentration is presented. The temperature dependence of the brine viscosity is described using the Vogel-Tammann-Fulcher (VTF) equation type asymptotic exponential function. The parameters of this equation are correlated with the brine concentration. This approach for developing accurate empirical correlations is verified by means of experimental data. The present approach is proven to lead to accurate correlations of the brine viscosity using a mathematically simple, but theoretically-meaningful equation, when reliable experimental data is available.
A New Approach for Early Gas Kick Detection
Authors: Li Xiangfang , Guan Congxiao , Sui Xiuxiang , Gangtao _
Published: January 2008

The propagation theory of acoustic wave and flow-rate wave in drilling fluid circulation system is investigated. Both theory analysis and our experimentsshow that early gas kick can be detected by flow-rate wave in the system. The propagation principle of flow-rate wave is the same as that of sound wave. We have found that the signal anti-interference capacity of flow- rate wave is much better than that of sound wave. Our new approach was verified through offshore rig tests.

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Effect of Flow Improver on Indian Western Offshore Crude -Carrying Pipe Line: A Case Study
Authors: Koshel K. C. , Kapoor S.
Published: January 2008

India's most promising two decade oil find in Western Offshore is contributing about 2/3rd towards national oil kitty. The oil of this province has intrinsic characteristics of high wax content to the tune of 14-16%. The wax deposition in main oil line (MOL) is observed during various condition monitoring programs. The paraffin deposition in the industry has been one of the long standing problems and continuous deposition results in reduction of internal diameter and increase in pumping pressure etc. The crude oil is transported through 203 km (30") pipe line from offshore to onland terminal. The British Gas Corporation has estimated about 20,000 m3 of wax deposited in the line.

An attempt has been made in the paper to evaluate the effect of higher dose of PPD (upto 700 ppm) as compared to normal dose of 300-350 ppm to ascertain the efficacy of PPD to pick up the already deposited wax. Studies were also made to identify chemicals which can disperse the deposited wax. The field studies conclude that the higher dose of flow improver improves the rheological parameters as well as lower the pour point without any appreciable picking up characteristics from the already deposited wax in the MOL. Further studies on the bench scale model suggest that a combination of PPD and wax dispersant can resolve the problem to some extent and may reduce the frequency of pigging.
Development of an Effects-Based Approach to Reporting Environmental Performance for the E&P Sector
Authors: King A. , Kerr S. A. , Holgate M. J. M.
Published: January 2008

Environmental reporting is widespread across industrial sectors and is virtually universal in the E&P sector. The quality of reporting is, however, mixed and is dominated by the reporting of waste steams. Communication of environmental performance is therefore poor. This paper proposes the adoption of an effects-based environmental reporting system, aggregating emissions data by their contribution to environmental themes. It is concluded that such a system would improve the clarity and resonance of environmental reporting within organisations and with external stakeholders. It is felt that this would improve strategic environmental management and would be of commercial benefit to companies as approaches to environmental regulation develop towards self-regulation.
Innovative Interactive Web Site Provides Oil Field Emergency Response Resources
Authors: Veil J. A. , LePoire D. J. , Richmond P. D. , Roloff K. G. , Gasper J. R. , Johnson R. L.
Published: January 2008

Emergency responders historically have not been provided with specialized training or assistance for spills and fires at oil field sites. This situation has lead to potential safety hazards for responders, and, in some cases, inappropriate response efforts have been made. Planning for emergency oil field incidents has been hampered by the sheer number of individual oil field sites. The Ohio Department of Natural Resources, in conjunction with the Ohio oil and gas industry, conceived a multimedia program to provide training and resources to emergency responders for dealing with oil field emergencies and to provide better resources to response planners. Argonne National Laboratory (Argonne), through funding from the U.S. Department of Energy's National Petroleum Technology Office, developed an innovative interactive web site that provides online information to emergency responders and response planners.

The web site consists of three modules that allow responders and planners to rapidly obtain information about well sites. The "Find a Well" module utilizes multiple graphical information system (GIS) layers and the Ohio Risk-Based Data Management System (RBDMS) database to allow users to identify well owner/operators, and well proximity to roads, streams, schools, and other important features. Using Argonne's Maps and Data (MaD) Java applet, users are able to download and interact with detailed maps by using standard web browsers. The web site also includes "Reporting" and "Resources" modules to provide information to users on the necessary reporting requirements following a spill or fire, as well as access to many other government and private resources for additional information.

The Ohio web site is considered to be a pilot project and can be modified for use in other states or for other purposes, such as Safe Drinking Water Act source water protection programs, for example. Depending on a user's needs, additional GIS data layers can be added to the system to provide more information.
Tapping Intellectual Capital for Service Improvement
Authors: Beatty Jonathan E. , Conners Sandra L. , Day Peter R. , Martin Charles A. , Regrain Emmanuelle A.
Published: January 2008

Increasingly, oil and gas companies look to service providers to deliver validated solutions for difficult operational problems, quickly and dependably. This paper describes a transformation program designed to meet this need and create a quantum leap in operational efficiency and service. Descriptions with lessons learned are outlined for the two components of the program—a support organization that links service delivery personnel directly with technology centers and other parts of the field and a knowledge management (KM) methodology that encourages knowledge sharing and reuse. Specifically the paper describes the program's support organization, information technology (IT) tools, processes, metrics, and change management, including training, communications, and recognition.

The primary application of this enabler is to maximize the performance of field engineers by providing secure, convenient access to validated information such as best practices or to expert groups for virtual collaboration. In addition the impact on new technology development, technology sustaining, and service training and documentation has been substantial.

Results have been excellent in service improvement, product development, and financial benefits.
Qualification of Two High Temperature Shearing Blind Ram Systems
Authors: Parker Bruce G. , Arora J. K.
Published: January 2008

Shearing blind rams are used in ram type blowout preventers to shear drill pipe, casing, tubing, and wireline cables in the wellbore. Once the above items are cut, the rams containing elastomeric sealing elements, must be able to seal and contain the wellbore pressure. This paper covers the development and testing of the elastomeric sealing elements used in two different high temperature shearing blind ram systems.
Development and Testing of a Fully Automated System to Accurately Control Downhole Pressure During Drilling Operations
Authors: van Riet E. J. , Reitsma D. , Vandecraen B.
Published: January 2008

Accurate control over bottomhole pressure during drilling is essential as the industry meets increasingly challenging drilling environments such narrow drilling margin formations, HPHT wells and fractured formations.

To increase the accuracy of the control over bottom hole pressures during drilling, a fully automated prototype system consisting of a hydraulics simulator, a computer controlled choke manifold and a pump as part of the mud return system has been developed and tested.

Rather than mud density alone, the system uses a reduced density mud in combination with a variable back-pressure at the annulus exit to achieve the required downhole pressure. The system is able to substantially compensate downhole pressure variations induced by the drilling operation by varying the surface back-pressure.

A number of possible advantages are associated with the use of the system: Reduction of formation impairmentReduction of mud lossesReduction of formation fluid influxIncreased ROPNo flat time during weight-up/downPotential to reduce number of casing stringsAutomatic kick circulation

A successful experimental program has been conducted on a real size test well in preparation of a field test sequence.

The system was easily retrofitted to the existing test rig and normal drilling procedures were minimally impacted.
Sand Production Prediction Study Using Empirical and Laboratory Approach for a Multi-Field Gas Development
Authors: Yeow Lei-Ming , Johar Zurita , Wu Bailin , Tan Chee , Yaakub Mohd Azriyuddin
Published: January 2008

A study using field and laboratory measurements to predict sand production for a multi-field gas development in offshore Peninsular Malaysia was carried out. Formation depths ranged from 1225 to 2450 metres with most of these fields having high CO2 and H2S content. Laboratory-derived properties were correlated with the openhole logs while the magnitudes of the in-situ stresses and formation pressure were derived from analysis of openhole logs, standard leak-off test data, coefficient of active earth pressure and qualitative stress information relating to the in-situ stress regime.

The sand production prediction model was calibrated against laboratory perforation collapse tests. The effect of well inclination/orientation, perforation orientation, reservoir pressure depletion and water-cut on sand production potential was evaluated. As downhole sand control increases well cost significantly and impairs well productivity, an assessment of the likelihood of sand production to decide if sand control is necessary and the timing of installation becomes very critical.

Sand production was found to be not a problem in the early part of the production of the fields with high reservoir pressures and low water-cut. Two over-pressured formations may have sand production problem with declining reservoir pressures. Based on the results of the study and expected reservoir pressures, drawdown and water-cut behavior of the fields, downhole sand control will not be required in the early stage of production.

This paper described the work done, techniques used, impact of the results of the study on the field development and benefits gained from the study.
A Case Study: Maximizing Asset Value Through Integrated Pipeline & Compression Optimization
Authors: Sutjahjo Andreas , Zainuddin Apriandy , Udianto Dewo , Wibowo Triono Hari , Hutagalung Harwan , Arifin Arifin , Prihartono Yoseph A. , Panjaitan Pahala R. , Supriyanto Herry
Published: January 2008

VICO Indonesia is one of three East Kalimantan gas producers, and produces around 1000 MMscf/d from four main fields; Badak, Nilam, Semberah and Mutiara (Fig.1&2). VICO has also been appointed as the Gas Co-ordinator and Pipeline Custodian for East Kalimantan. The main objective of Gas Co-ordination role is to ensure reliable gas supply to the Bontang LNG plant located approximately 60kms north of the Badak Camp.

As gas fields mature, there is a requirement for the compressor utilization in each field be optimized. The optimization performed has included in field optimization, integrated intra-field compressor utilization and optimization of the East Kalimantan pipeline network. The target of this optimization is to increase gas deliverability and reserves recovery whilst minimising capital investment. In the past each asset developed its own compression strategy focused on the best value for the asset. For the last 5 years this has been expanded to include the identification of synergies with other assets, i.e. by sharing or removing idle equipment. This year, as a further development, VICO incorporated the East Kalimantan joint operated pipeline network into the optimization to determine a strategy that would give the best value for all the East Kalimantan gas producers.

The multi disciplinary study team identified excess compression capacity in one of the assets. The Field Depletion Planning model (FPM), which integrates the subsurface work program with compression and pipeline optimization, was used to identify options for utilization of this excess capacity. Each option was reviewed from the technical and economical standpoint. Gas deliverability, reserves recovery and cost are the key review parameters. The team also considered the impact on the volume of future subsurface work programs and the operational consequences.

The study recommended the installation of a small pipeline system modification to allow gas from one field to be compressed at another field. The project not only gives higher gas deliverability and incremental reserves recovery, but also allows flexibility for major pipeline contingency plans. This project is economically justified and could also provide possible future compression utilization for the neighbouring gas producers.
Malaysian Larut Drilling - Pushing the Envelope in Extended Interval Drilling
Authors: Nasir Adrin Shafil Bin Ahmad , Yaacob Zaidi
Published: January 2008

This paper presents a case history of a systematic approach to extending the typical open-hole section length seen in ExxonMobil Exploration & Production Malaysia Inc (EMEPMI) wells offshore the east coast of Peninsular Malaysia. Incremental improvements in shallower wells have allowed acceleration of the learning curve for use in the deeper, more complex wells. This approach was successfully completed at the Larut Platform with project wells breaking Malaysian records for open-hole section lengths and total measured depth, while minimizing the casing strings required and overall well cost.

With prior drilling experience limited to relatively shallow wells of about 4000 meters (m) measured depth (MD), there was a concern that Malay Basin formations would not support open-hole sections with lengths greater than 2200m. To meet this challenge, successive Larut wells were planned with incremental increases in open-hole section length of up to 200m. Drilling parameters were monitored and documented in these wells to calibrate predicted torque and drag values for future extended reach wells in the development program.

Drilling the first well in Larut Field resulted in little non-productive time associated with open-hole length or other related problems. As the open-hole section was systematically lengthened in subsequent wells, clean up time associated with circulation and back reaming operations at connections was optimized to compensate for the increased hole section length. Drilling data from the early wells provided credible friction factors which when used to model torque and drag in future extended reach wells did not predict any significant increase in risk for extending the open-hole sections.

The documented data in the early step-out wells allowed the team to refine and execute best practices in hole cleaning and operational practices to suit even longer hole section drilling. The Larut program successfully pushed the envelope and produced two Malaysian record breaking wells with total depths (TD) greater than 5900m initially and then 6300m, both with a horizontal displacement (HD) to true vertical depth (TVD) ratio of 2.5. The project savings associated with pushing the envelope exceeds $4,000k USD to date.
Thru-Tubing Zonal Isolation and Water Shut-Off Utilizing Coiled Tubing in the Java Sea: Operational Challenge & Treatment Strategy
Authors: Susilo Yoliandri , Hendarwin Hendarwin , Wibowo Wahju , Tobing Budhira L. , Imam Arbai , Hendra Yasri S.
Published: January 2008

Almost all the wells in the Offshore North West Java (ONWJ) field penetrate multi-layer reservoirs. To accommodate reservoir management issues, most of these wells were therefore completed in multiple packer completions (dual or single string with multiple packer). As the field is getting mature, more wells are becoming wet and consequently more wells are dying due to water encroachment. Therefore, remedial actions to revive dead wells play an important role to maximize the revenue. To address this issue, thru-tubing cement squeeze and polymer squeeze using coiled tubing have proved to be efficient methods to reduce water production by isolating watered out zones in the ONWJ field.

However, the operation of this job can be more complicated when done in multiple packer completion or in dual completion cases, especially when the tubing has leaks in order to avoid the cement or polymer from penetrating other places or productive zones. In several cases, the condition of old tubing that has experienced deformation (buckling/collapse) has made the task even more challenging. Therefore, treatment strategies must be designed carefully for successful cement/polymer placements into the target zone without affecting production from the other string or zones.

From 1999 to 2003, a total of 36 thru-tubing zonal isolation & water shut-off jobs utilizing coiled tubing were done with a high degree of success, although in many cases the tubing had leaks and mechanical problems. Several methods were used and modified to ensure proper cement or polymer placement. Through the use of the innovative "cement packer" technique and inflatable packer, the jobs were accomplished successfully. The coiled tubing has proven to be an effective solution to deal with well conditions in the ONWJ field.

This paper will also discuss three case histories, with each case representing different operational challenges.
Accounting for Dispersion in Injectivity Decline: Travelling Wave Flow Regimes
Authors: Altoé F. J. E. , Bedrikovetsky P. , Siqueira A. G. , de Souza A. L. S. , Shecaira F. S.
Published: January 2008

During the sea/produced water injection, the permeability decline occurs,resulting in well impairment. Solid and liquid particles dispersed in theinjected water are trapped by the porous medium and may increase significantlythe hydraulic resistance to the flow.

Impairment of injectors by injected/reinjected water of a poor qualitypresent a serious problem for development of oil fields submitted towaterflooding.

Similar problems occur in environmental engineering. Propagation ofbacteria, viruses and contaminants in ground water reservoirs present seriousenvironmental concerns. Design and planning of environmental protectionmeasures should be based on reliable mathematical modelling.

The particle transport in porous media is determined by an advective flow ofcarrier water and by hydrodynamic dispersion in micro heterogeneous media. So,the particle flux is a total of advective and dispersive fluxes. Transport ofparticle suspensions in porous media is described by the advection-diffusionequation and by the equation of particle capture kinetics. The conventionalmodel for deep bed filtration accounts for hydrodynamic particle dispersion inmass balance equation but does not consider impact of dispersive flux inretention kinetics.

In the present study, the model for deep bed filtration accounting forparticle hydrodynamic dispersion in both mass balance and retention kineticsequations is proposed. The travelling wave solution was found for the blockingfunction type of filtration coefficient (that becomes zero after the depositreaches some critical value). This critical value can be determined from the particle breakthrough time.
Simulation of Naturally Fractured Reservoirs Utilizing an Effective Time-Splitting and Up-scaling Methods
Authors: Sutopo Sutopo
Published: January 2008

The single-continuum approach employing effective permeability is one of the practical methods for simulating naturally fractured reservoirs. The mixed finite volume element (MFVE) method for full-tensor model was used to deal with permeability tensors resulted from upscaling of fractured systems.

The governing equations can effectively be formulated in fractional flow equations; i.e. in terms of global pressure and saturation equations. An algorithm is implemented applying a highly accurate numerical approach based on the MFVE method for discretizing the pressure equation, and a combination of the MFVE and the finite volume element (FVE) methods for the saturation equation. The saturation equation is discretized by means of a time-splitting algorithm that allows an explicit time stepping for FVE applied to the advection equation, and an implicit time stepping for MFVE applied to the corrective equation of capillary diffusion.

Four fracture systems comprise discrete non-crossing fractures distributed randomly. Numerical experiments of 2-D flow are presented to demonstrate the efficiency and robustness of the time-splitting technique and upscaling for simulation of fractured reservoirs.
Enhanced Oil Recovery and Elimination of Gas Coning by Using Salt Crystals
Authors: Koncz I. , Megyery M. , Szittar A. , Tiszai Gy.
Published: January 2008

A procedure is presented by which increased oil recovery from vertically heterogeneous reservoirs during gas flooding and/or elimination of the impacts of gas coning in gas-cut wells can be achieved. In this procedure, sodium chloride-saturated brine is injected into the layered, heterogeneous reservoir causing flood mainly in its more permeable zones. When the quantity of the solvent (water) and/or the solubility of the salt is diminished, salt crystals will precipitate in the pores of the reservoir. The crystals block mostly the more permeable parts of the reservoir which may result in reduced reservoir heterogeneity and - consequently - volumetrically more entire gas (e.g. carbon dioxide) flooding of the reservoir. The procedure, resulting in selective profile modification ensures more effective oil recovery by increasing the volumetric sweep efficiency. A field-scale project was prepared for a heterogeneous sandstone reservoir in Hungary that had been previously developed by CO2 drive. The economical estimation indicates a positive result.

Similar selective profile modification can be attained in oil-producing wells having unfavorable gas production caused by gas coning. The gas-cut pay zone can be blocked by in situ salt precipitation and the oil production of the well can be restituted. A successful gas coning elimination was carried out in the sandstone reservoir of Algyő field, Hungary. Gas coning was observed in the well, which was able to produce oil only periodically before the treatment. The well continuously produced 7400 m3 (46500 bbl) oil after the treatment including 3050 m3 (19200 bbl) excess oil recovery. In 2002, successful gas coning elimination was performed on four wells. (One of them was horizontal.) Further treatments are planned on five wells in 2003.
Thru-Tubing Zonal Isolation and Water Shut-Off Utilizing Coiled Tubing in the Java Sea
Authors: Susilo Yoliandri , Wibowo Wahju , Hendarwin Hendarwin , Tobing Budhira L. , Arbai Imam , Hendra Yasri S.
Published: January 2008

Almost all the wells in the Offshore North West Java (ONWJ) field penetrate multi-layer reservoirs. To accommodate reservoir management issues, most of these wells were therefore completed in multiple packer completions (dual or single string with multiple packer). As the field is getting mature, more wells are becoming wet and consequently more wells are dying due to water encroachment. Therefore, remedial actions to revive dead wells play an important role to maximize the revenue. To address this issue, thru-tubing cement squeeze and polymer squeeze using coiled tubing have proved to be efficient methods to reduce water production by isolating watered out zones in the ONWJ field.

However, the operation of this job can be more complicated when done in multiple packer completion or in dual completion cases, especially when the tubing has leaks in order to avoid the cement or polymer from penetrating other places or productive zones. In several cases, the condition of old tubing that has experienced deformation (buckling/collapse) has made the task even more challenging. Therefore, treatment strategies must be designed carefully for successful cement/polymer placements into the target zone without affecting production from the other string or zones.

From 1999 to 2003, a total of 36 thru-tubing zonal isolation & water shut-off jobs utilizing coiled tubing were done with a high degree of success, although in many cases the tubing had leaks and mechanical problems. Several methods were used and modified to ensure proper cement or polymer placement. Through the use of the innovative "cement packer" technique and inflatable packer, the jobs were accomplished successfully. The coiled tubing has proven to be an effective solution to deal with well conditions in the ONWJ field.

This paper will also discuss three case histories, with each case representing different operational challenges.
Incorporating Uncertainties in Well-Count Optimization With Experimental Design for the Deepwater Agbami Field
Authors: Narahara G. M. , Spokes J. J. , Brennan D. D. , Maxwell G. , Bast M.
Published: January 2008

This paper describes a methodology for incorporating uncertainties in the optimization of well count for the deepwater Agbami Field development. The lack of substantial reservoir description data is common in many deepwater discoveries. Therefore, the development plan must be optimized and proven to be robust for a wide range of uncertainties. In the Agbami project, the design of experiments or experimental design (ED) technique was incorporated to optimize the well count across a wide range of subsurface uncertainties.

The lack of substantial reservoir description data is common for many deepwater discoveries. In the Agbami project, the uncertainty in oil in place was significant (greater than a factor of two). This uncertainty was captured in a range of earth (geologic) models. Additional uncertainty variables, including permeability, fault seals, and injection conformance, were studied concurrently. Multiple well count development plans (high, mid, and low) were developed and used as a variable in ED. The ED technique allowed multiple well counts to be quickly tested against multiple geologic models. With the net present value (NPV) calculated for each case, not only was the well count for the overall highest NPV determined, but discrete testing of each geologic model determined the optimum well count for each model. The process allowed testing the robustness of any well count versus any uncertainty (or set of uncertainties).

A method was demonstrated quantifying the difference between perfect and imperfect knowledge of the reservoir description (geologic model) as it pertains to well locations.
Progressing Cavity Pump (PCP) Behavior in Multiphase Conditions
Authors: Bratu C.
Published: January 2008

In operation, the Progressing Cavity Pumps (PCP) boosting gaseous multiphase mixture faces reliability issues that can be summarized as follows: the pump pressure is developed by the stages nearest the discharge, then the high pressure gradient causes heat to build up which commonly results in premature failure of the elastomeric stator. This paper first describes our recent testing program performed with an industrial PCP in multiphase conditions, and then presents a new analytical model that describes the thermo-hydraulic-mechanic processes which occur when attempting to pump multiphase mixtures. The objectives of our program are to: (1) examine the PCP system operating at high gas volume fraction, (2) analyze the pumping performance (delivered pressure, flow rate, and gas void fraction) and, (3) describe the overheating generated when the gas is compressed. This paper also describes our PCP experimental program and presents resulting experimental datas which clearly show the correlation between the pressure distribution and the heat along the pump. We formally explain this phenomenon by proposing a new analytical model that evaluates the stator degradation and failure risk. This paper should help operators and manufacturers to design pumps with better system's Mean Time Between Failure (MTBF) performance.
Pressure Variations Inside the Hydraulic Fracture and Its Impact on Fracture Propagation, Conductivity, and Screenout
Authors: Daneshy A. A.
Published: January 2008

Field measurement of fluid pressure inside hydraulic fractures have shown rapid pressure decline along fracture length. The consequence of this pressure profile is rapidly tapering fracture width. This means that a disproportionate volume of fluid and proppant injected inside hydraulic fractures remain near the wellbore, thus creating excessive near wellbore and substantially less far field fracture conductivity. This explains why history matching of oil well productions yields much lower effective fracture lengths than gas wells, since oil wells because of their higher permeability require higher fracture flow capacity.

The rapid tapering of the fracture width also restricts the movement of the proppant inside the fracture, causing its accumulation near the wellbore. As the treatment progresses, and if sufficient proppant volume has been injected inside the fracture, the near wellbore segment of the fracture can begin to fill with proppant, thus reducing the open width available for further movement of the fluid. Essentially, accumulation of proppant near the wellbore reduces the fracture width available for fluid flow which then results in higher frictional pressure losses inside the fracture, further skewing the pressure distribution, and eventually screen-out.
Field Pilots of Microbial Flooding in High-Temperature and High-Salt Reservoirs
Authors: Zhao H. , Li Z. , Zhao P. , Wu Y.
Published: January 2008

This paper describes the laboratory tests, including bacteria screening, bacteria culturing and nutrient solution screening for microbial flooding in water injection wells in High Temperature and High Salt Reservoirs(HTHS) reservoirs with temperature of 85°C and salinity of 12×104mg/l in Wenmingzhai Oilfield. The microbes and their nutrient solutions have been cultured through directed domestication of bacteria in injected water, microbe adaptability evaluation and simulation tests of oil flooding in cores. The well selection principles, injection occasions in field tests and the injection process are presented. The technology were successfully applied in 12 wells and result show that microbial flooding resulted in stable wellbore pressure and better water injection profile. Water cut was reduced and oil production rate was increased in corresponding oil wells,. Total oil increasment was 9536 tons. The microbial mother solution with 1×108 microbes per ml obtained 53t oil increasment, with a benefit and investment ratio of 1: 5.5. Therefore, this microbial flooding process is of great economic benefit and good application prospect.
Understanding Reservoir Performance and Uncertainty Using a Multiple History Matching Process
Authors: Bustamante D. S. , Keller D. R. , Monson G. D.
Published: January 2008

This paper describes the history matching and predictive case studies of two deepwater Gulf of Mexico (GOM) fields using an advanced Bayes linear estimation tool. Advantages of the tool include significant acceleration of the history matching process, identification and quality measurements of multiple history matches, quantification of reservoir uncertainty, and an improved understanding of reservoir performance. Additionally, a statistical estimator of predictive simulation results is created to generate statistically valid confidence intervals around performance predictions. This paper describes a practical workflow incorporating this tool to rapidly evaluate deepwater producing gas fields, and illustrates its use to determine remaining field potential and future development requirements of two fields, the Harrier and the Raptor Fields in the Pioneer Natural Resources-operated Falcon Corridor.
Efficient Design of Reservoir Simulation Studies for Development and Optimization
Authors: Kalla Subhash , White Christopher D.
Published: January 2008

Development studies examine geologic, engineering, and economic factors to formulate and optimize production plans. If there are many factors, these studies are prohibitively expensive unless simulation runs are chosen efficiently.

Experimental design and response models improve study efficiency and have been widely applied in reservoir engineering. To approximate nonlinear oil and gas reservoir responses, designs must consider factors at more than two levels—not just high and low values. However, multilevel designs require many simulations, especially if many factors are being considered. Partial factorial and mixed designs are more efficient than full factorials, but multilevel partial factorial designs are difficult to formulate. Alternatively, orthogonal arrays (OAs) and nearly-orthogonal arrays (NOAs) provide the required design properties and can handle many factors. These designs span the factor space with fewer runs, can be manipulated easily, and are appropriate for computer experiments.

The proposed methods were used to model a gas well with water coning. Eleven geologic factors were varied while optimizing three engineering factors. An NOA was specified with three levels for eight factors and four levels for the remaining six factors. The proposed design required 36 simulations compared to 26,873,856 runs for a full factorial design. Kriged response surfaces are compared to polynomial regression surfaces. Polynomial-response models are used to optimize completion length, tubinghead pressure, and tubing diameter for a partially penetrating well in a gas reservoir with uncertain properties.

OAs, Hammersley sequences (HSs), and response models offer a flexible, efficient framework for reservoir simulation studies.
Wettability Alteration to Intermediate Gas-Wetting in Gas-Condensate Reservoirs at High Temperatures
Authors: Fahes Mashhad , Firoozabadi Abbas
Published: January 2008

Wettability of two types of sandstone cores, Berea (permeability on the order of 600 md), and a reservoir rock (permeability on the order of 10 md), is altered from liquid-wetting to intermediate gas-wetting at a high temperature of 140°C. Previous work on wettability alteration to intermediate gas-wetting has been limited to 90°C. In this work, chemicals previously used at 90°C for wettability alteration are found to be ineffective at 140°C. New chemicals are used that alter wettability at high temperatures. The results show that: (1) wettability could be permanently altered from liquid-wetting to intermediate gas-wetting at high reservoir temperatures, (2) wettability alteration has a substantial effect on increasing liquid mobility at reservoir conditions, (3) wettability alteration results in improved gas productivity, and (4) wettability alteration does not have a measurable effect on the absolute permeability of the rock for some chemicals. We also find the reservoir rock, unlike Berea, is not strongly water-wet in the gas/water/ rock system.
Implementation of Tree Cutting Best Practice Based on Reduced Impact Logging Guidelines for Indonesia on Tangguh LNG Project
Authors: Narwoko Narwoko
Published: January 2008

For years forestry practice has not been conducted wisely per applicable regulation and standard which in turn create significant long term impact to the surrounding forestry areas as well as disturb the long term sustainable growth of the forest that finally impacted the community life and biodiversity of the area.

Tangguh LNG Facilities is located in production forest on Bintuni Bay Regency, Papua, Indonesia. Total land purchased by project is 3266ha. Construction of the facilities requires the clearing of some 800 ha production forest and the remaining area of about 2400 ha will be maintained as buffer zone area. Perimeter fence will be developed to protect the buffer zone area. Construction of the facilities in such area with rich biodiversity is a challenging effort particularly to minimize the impacts to the surrounding forests in compliance with the Indonesian and international regulation and standards, and to ensure the biodiversity protection and environmental protection of the forest area.

To achieve the objectives, Tangguh LNG Project develops and implements the tree cutting and land clearing plan to comply with the Indonesia applicable regulations and International best practice including the implementation of Reduced Impact Logging Guidelines for Indonesia. The plan developed by forestry experts and implemented with full supervision from project team. A number of compliance checklists have been developed to ease the implementation of the plan which also helps to track any deviation of the implementation to the said plan.

With the implementation of such plan up to the current stage of the project, minimization of impact to the surrounding area could be achieved and it is expected that in overall the project activities and the operation of the facilities could minimize the negative impact and maximize its positive impact to the area. This will harmonize the existence of the facilities with the surrounding environment so Industrial facilities are not perceived anymore as the major source of environmental impact.
Petrophysical Type Curves for Identifying the Electrical Character of Petroleum Reservoirs
Authors: Worthington Paul F.
Published: January 2008

A user-friendly type chart has been constructed as an aid to the evaluation of water saturation from well logs. It provides a basis for the inter-reservoir comparison of electrical character in terms of adherence to, or departures from, Archie conditions in the presence of significant shaliness and/or low formation-water salinity. Therefore, it constitutes an analog facility. The deliverables include reservoir classification to guide well-log analysis, a protocol for optimizing the acquisition of special core data in support of log analysis, and reservoir characterization in terms of an (analog) porosity exponent and saturation exponent.

The type chart describes a continuum of electrical behavior for both water and hydrocarbon zones. This is important because some reservoir rocks can conform to Archie conditions in the fully water-saturated state, but show pronounced departures from Archie conditions in the partially water-saturated state. In this respect, the chart is an extension of earlier approaches that were restricted to the water zone. This extension is achieved by adopting a generalized geometric factor—the ratio of water conductivity to formation conductivity—regardless of the degree of hydrocarbon saturation. The type chart relates a normalized form of this geometric factor to formation-water conductivity, a "shale" conductivity term, and (irreducible) water saturation. The chart has been validated using core data from comprehensively studied reservoirs.

A workflow details the application of the type chart to core and/or log data. The analog role of the chart is illustrated for reservoir units that show different levels of non-Archie effects. The application of the method should take rock types, scale effects, the degree of core sampling, and net reservoir criteria into account. The principal benefit is a reduced uncertainty in the choice of a procedure for the petrophysical evaluation of water saturation, especially at an early stage in the appraisal/development process, when adequate characterizing data may not be available.
Application of Gas Lift to Heavy-Oil Reservoir in Intercampo Oilfield, Venezuela
Authors: Hong'en D. , Yuwen C. , Dandan H. , Wenxin C. , Guozhen Z.
Published: January 2008

This paper presents successful applications of the gas lift to heavy oil reservoirs in Intercampo oilfield, Lake Maracaibo. Liquid production rate ranges from 50 to 2000 bbl per day per well, gas lift was selected as the first artificial lift method in the oilfield. The paper expresses the gas lift mechanisms in high water cut with lower API degree in heavy oil reservoirs. The theory analysis showed that injection gas rate of gas lift and GOR of oil well have direct effects on fluid flow state in wellbore.

Scenarios of theory design and actual production of gas lift were described in the paper. For artificial lift design, the paper points out the correlation equations of gas lift for heavy crude reservoirs that their flow behavior of actual situation should not characterized by present equations, therefore, there are big error value between theory design and actual production when producer is high water cut with lower API degree. In addition, the error created reason was analyzed and oil well normal production in high water cut stages with lower API degree was emphasized, in the case, emulsion of water and oil should not happen.

A corrected coefficient of gas lift design was provided under the high water cut with lower API degree. Nowadays, for the new correlations are very preliminary that will need to be developed by means of production engineers and researchers further. It is particularly important to production engineers in optimization and design of gas lifting equipments.
Is It Possible To Treat Produced Water for Recycle and Beneficial Reuse?
Authors: Hum F. , Tsang P. , Kantzas A. , Harding T.
Published: January 2008

Fresh water scarcity and increasing demand are worldwide concerns and are being addressed by a number of water management initiatives in Alberta and Canada. In 2003, 0.3 billion m3 of produced water was injected into disposal wells associated with oil and gas production in Alberta. This volume of water is a potential resource for recycling and beneficial reuse in Alberta, which would have a significant impact on sustainable development in Alberta. This water must first be treated to meet water quality requirements and regulatory guidelines for specific applications. This paper provides a comprehensive technical and economic review of water treatment technologies and shows that water treatment processes are commercially available. Although the cost of implementing suitable treating processes to meet drinking water quality guideline is estimated at three times the current cost of municipal water supply in Alberta, it is more feasible to recycle produced water for other purposes, such as agricultural or petroleum application (i.e., waterflooding, etc.). This is because water quality guidelines for most other applications are not as stringent as that for drinking water and there is increasing public resistance for industry to use fresh water for commercial applications. A multi-disciplinary research and development team studying water recycle and beneficial reuse is necessary to look into these issues. The University of Calgary is set to collaborate on such projects due to the current research emphasis on sustainable energy and environmental impact. Collaboration between the government, industry and academia to develop initiatives aimed at reducing fresh water is possible in Calgary for several reasons. One is the proximity of many major oil and gas companies in this city, which would allow for easy communication. Another is the fact that the current price of oil would not inhibit producing companies from investing in this kind of research. The result can be well-developed initiatives to treat and recycle produced water for beneficial reuse, thus reducing fresh water demand for many applications in the petroleum and agricultural industries.
Recovery Performance and Economics of Steam/Propane Hybrid Process
Authors: Deng X.
Published: January 2008

In this study, a particular hybrid process with propane and steam co-injected is simulated numerically under different operation strategies. The roles of propane in the hybrid process are investigated. The economics of these hybrid processes are also evaluated with a supply cost model. Results show that hybrid processes with steam and propane co-injection can have the same supply cost as that of SAGD process and propane-related cost is a small part of the total supply cost in these hybrid processes due to the small amount of propane used in this study. Results also show that low pressure hybrid processes are more cost-efficient than their high pressure counterparts.
ITM Oxygen for Gasification
Authors: Armstrong P. A. , Foster E. P. , Gunardson H. H.
Published: January 2008

An Air Products-led team is developing a new air separation technology - Ion Transport Membrane Oxygen - based on ceramic membranes that selectively transport oxygen ions when operated at high temperature. Under the influence of an oxygen partial-pressure driving force, the ITM Oxygen process achieves a high-purity, high-flux separation of oxygen from air. By integrating the energy-rich, vitiated, non-permeate stream with a gas turbine system, the overall process co-produces high-purity oxygen, power, and steam if desired. As a result, the technology is ideally suited for advanced energy conversion processes such as IGCC that require oxygen and use heavy carbonaceous feedstocks (resid oils, bitumens, coke, coal), as well as for traditional industrial applications for oxygen and distributed power.

During Phases I and II of a three-phase development program with the U.S. Department of Energy, the ITM Oxygen team established the feasibility of the ceramic membrane approach and designed and built commercial-scale membrane modules. A prototype facility that will produce 5 tons-per-day of oxygen will start up this year. Larger-scale test rigs are planned, with commercialization projected in the latter part of the decade.

This paper will present an overview and status of the ITM Oxygen development effort, and the integration into gasification and clean energy processes. Process integration options will be discussed and contrasted. The economic benefits compared to the best commercial air separation alternative will be highlighted.