bluuebunny/crossref_metadata_2025 huggingface dataset:
Multidisciplinary Workflow for Oil Fields Reservoir Studies - Case History: Meleiha Field in Western Desert, Egypt
Authors: Campobasso S. , Gavana A. , Bellentani G. , Pentoli I. , Pontiggia M. , Villani L. , Abdelsamad T. H.
Published: December 2007

Coping with mature fields located in lithologically complex formations is a difficult task. The large amount of data and information acquired during the field history requires a tight cooperation between different disciplines to pursue the objective of the reservoir study in the most effective manner. A typical result of this work is the development of new integrated tools to:

handle and integrate different types of geological data help in solving the history match problems define the optimum locations for infilling wells derive reliable production forecast cases

This paper illustrates the Case History of Meleiha Field, where team work and new technologies were applied aiming to support an intense infilling campaign through a reliable simulation of the fluids flow in the reservoir and to predict future field behaviour in terms of oil rate, water cut, GOR and pressure.

Meleiha Field, located in the Western Egyptian Desert, consists of four pools with five oil-bearing intervals in the lithologically complex Bahariya Formation, lying at a depth of some 5000 ft TVDSS and characterized by thin intercalations of sands, glauconitic sands, cemented sands, shales and carbonates.

Production commenced in December 1984, with artificial lift well completions; oil recovery was initially via natural depletion and then enhanced through water injection.

The integration of petrophysical facies characterization and sedimentological model with a suitable geostatistical approach allowed to create a black-oil simulation model of these highly heterogeneous and complex reservoirs in order to achieve a reasonable history match.

Finally, the use of an optimization tool supported the selection of about 40 development wells locations.

Following the study indications, 10 wells have been already drilled with encouraging results both in terms of prognosis confirmation and, most important, of additional production.
Coiled Tubing Conveyed Fracturing System Allows Longer Zones to be Isolated in a Single Trip Multiple Times
Authors: Stricker M. P. , Romano F. J. , Plante M. E. , Holmes B.
Published: December 2007

Increased production and lower costs in shallow gas wells are closely linked to developing and refining new coiled-tubing drilling, completion, and production techniques. Innovations in coiled tubing have reduced the costs of drilling and completing these wells and increased their productivity and life cycles. Coiled-tubing fracturing is one such innovation. This has been used for some time now, predominantly in North American shallow gas wells. In these wells, the cost advantages associated with working over the well in a live condition while reducing job time are attractive.

Coiled-tubing fracturing operations usually employ straddle-type tool configurations. However, with a typical maximum lubricator length of about 30 ft, straddle interval lengths have been restricted, which increases the amount of resets required to effectively fracture individual zones. This restriction also increases the potential risk of communication above the assembly.

This paper describes the development of an economical and reliable coiled-tubing fracturing system that allows selective fracturing of previously bypassed pay zones. This is now possible because the system can be conveyed in a tandem configuration that works within current lubricator restrictions, but is capable of setting repeatedly as a retrievable bridge plug and treating packer combination. This allows longer zones to be precisely isolated multiple times in a single trip in hole.

This innovative technique can not only reduce intervention costs but also reduce the total time required to complete the operation. This paper will examine several case histories, with emphasis on pre-job planning, equipment selection, well site execution and post-job results.
An Effective Sweep—Cleaning of Large Deviated Wellbores Using Small Coiled-Tubing Systems
Authors: Surjaatmadja J. , Rosine R.
Published: December 2007

The use of coiled-tubing systems has proven practical and cost effective for many well intervention procedures. With the development of better quality, longer, and larger-sized coiled-tubing systems, the variety of processes available for using coiled-tubing systems continues to rise rapidly. One application is the removal of heavy solids through a deviated wellbore section, which causes immense difficulties to the operator. Even when the particulate drop rate through the carrier fluid is slow, this velocity is increased by up to ten times in deviated wellbore sections; which can cause failure, and even worse, sticking of tubing. A method that is successful in counteracting this phenomenon is discussed in this paper. The need for increased flow rates, meaning the use of larger coiled-tubing systems, is not necessary for this method; thus allowing effective cleanup through smaller production tubing.
WDDM, the Jewel of the Nile
Authors: Katamish H. E. , Steel N. , Smith A. , Thompson P.
Published: December 2007

Located in the Mediterranean around 110 km NE of Alexandria in water depths between 150 to 1600m.The concession, located in the Egyptian deepwater Nile Delta, was awarded to BG (operator) and Edison in 1995. The success story continues with an aggressive technology-enabled exploration and development programme, nine separate gas discoveries were made proving sufficient gas reserves for a substantial domestic market contract and two trains of LNG.

To develop these gas fields and overcome the associated technical challenges, BG and partners adopted cutting-edge technologies across all subsurface disciplines including; G&G: Thin beds evaluation; 3D reservoir characterization using seismic attributes; hybrid deterministic-stochastic sector and full-field geocellular modeling, shallow hazard assessment and pore pressure prediction from 3D seismic.Reservoir engineering: Integrated modeling techniques, upscaling, reservoir management practices, numerical well test modeling, reservoir/intelligent well completion interaction modeling, probabilistic reserves assessment and integrated field planning.Well engineering: Sand control in conjunction with intelligent sub-sea well completions; wet gas flow meter installation, high rate gas wells design.

The first WDDM fields to enter production, Scarab and Saffron, have been producing since March 2003 with peak production of + 800 mmscf/d to the Egyptian domestic market. The Scarab Saffron development is one of the longest sub sea tie backs in the world. First production from the Simian and Sienna fields to Train 1 of the plant (ELNG) at Idku is expected in 2005.

This paper highlights state-of-the-art exploration and development practices being undertaken in the WDDM concession where advanced technology has made a significant business contribution in delivering world class projects across the whole integrated gas chain.
Eliminating Multiple Interventions Using a Single Rig-Up Coiled-Tubing Solution
Authors: Kumar P. S. , Van Gisbergen S. , Harris J. , Ferdiansyah E. , Brady M. , Al Harthy S. , Pandey A.
Published: December 2007

This paper describes new methods to economically improve production levels in one of the mature fields of Petroleum Development Oman. This field had been developed by infill drilling programs, which were suspended in early 2001 to review the development strategy. A reservoir management team set a challenge to effectively conduct logging operations and quickly utilize the data collected to identify and avail of optimization opportunities, thus maximizing the production of the wells whilst lowering overall costs. The optimization activity consisted of clean-out, saturation logging, perforation and stimulation. These activities were carried out either with coiled tubing only utilizing conventional practises and e-line coiled tubing, or with the combination of coiled tubing and hoist through multiple well entries. Both of these methods were successfull in that they resulted in incremental net oil production but at relatively high costs.

This paper presents a methodology which enables clean-out, logging, stimulation and perforation with one coiled tubing intervention, which includes a plastic coated "e-line" coiled tubing, coiled tubing perforating head and new perforation technology. All systems are in complete compliance with the most stringent safety criteria. The new method has a considerable time and cost savings impact, and this is fully illustrated in this paper with field trial case histories, in which a multi-disciplinary team effectively targeted the most suitable zones for perforation and stimulation using a state of the art self diverting, non damaging, acid system. Technical and economic comparisons are made with conventional practices. The methodology is currently being employed in this field and is potentially applicable to other fields.
Towards an Industry Report on Environmental Performance
Authors: Campbell J. A. , Bennett W. M.
Published: December 2007

Since 1998, the International Association of Oil and Gas Producers (OGP) has been collecting and collating information on environmental performance from its member companies. The initiative has two principal purposes; first, it addresses the need for greater transparency of upstream industry activities and second, it can provide a means for contributing companies to compare their environmental performance, thereby leading to improved overall industry performance.

Member companies are asked to provide information on 6 categories: atmospheric emissions, produced water, muds and cuttings from offshore operations, oil spills, chemical spills and energy efficiency. Companies also provide information on production levels associated with the data for normalisation. Data are compiled by region (Africa, Asia/Australasia, Europe, FSU, Middle East, North America and South America).

Thirty OGP member companies representing over 40% of the world's oil production now participate in the reporting cycle. Other member companies have begun the internal processes that will enable their participation in future years. Data coverage is quite uneven; for example almost all production in Europe is reported whilst in other areas performance is reported for a relatively low fraction of the known production.

The reporting exercises have identified and taken steps to solve a range of problems associated with data recording and processing. Information can now be reported to the system via an electronic interface, thereby minimising data transcription errors; the system also allows (by a series of ‘flags’) for early detection of possibly spurious year-on-year variations in company reporting.

As the reporting mechanism has developed, the level of confidence within the participating companies has grown steadily and OGP released a summary of information on 2002 activities in 2003. This year, participating companies have agreed to publish data aggregated at a regional as well as a global level.
Quantification of Uncertainty in Relative Permeability for Coarse-Scale Reservoir Simulation
Authors: Okano H. , Pickup G. E. , Christie M. A. , Subbey S. , Sambridge M. , Monfared H.
Published: December 2007

Reservoir simulation to predict production performance requires two steps: one is history-matching, and the other is uncertainty quantification in forecasting. In the process of history-matching, rock relative permeability curves are often altered to reproduce production data. However, guidelines for changing the shape of the curves have not been clearly established. The aim of this paper is to clarify the possible influence of relative permeabilities on reservoir simulation using the uncertainty envelope.

We propose a method for adjusting the shape of relative permeability curves during history-matching at the coarse scale, using the Neighbourhood Approximation algorithm and B-spline parameterisation. After generating multiple history-matched models, we quantify the uncertainty envelope in a Bayesian framework. Our approach aims at encapsulating sub-grid heterogeneity in multi-phase functions directly in the coarse-scale model, and predicting uncertainty. In this sense, the framework differs from conventional procedures which perturb fine-scale features, upscale the models and evaluate each performance. In addition, B-spline parameterisation is flexible allowing the capture of local features in the relative permeability curves. The results of synthetic cases showed that the lack of knowledge of the subgrid permeability and the insufficient production data provoked a substantial amount of uncertainty in reservoir performance forecasting.
Petrophysical Seismic Inversion to Determine More Accurate and Precise Reservoir Properties
Authors: Bornard R. , Allo F. , Coleou T. , Freudenreich Y. , Caldwell D. H. , Hamman J. G.
Published: December 2007

We introduce a Stratigraphic inversion method that simultaneously integrates pre-stack seismic data with petrophysical and geological data. We use simulated annealing to invert directly for reservoir properties such as porosity, lithology and fluid content in a 3D geocellular model. Well and seismic data are integrated in their respective domains along with physical constraints at different vertical scales to produce an optimal solution. Application of user-defined Petro-Elastic Models (PEM) is a key element of the proposed methodology. In addition to connecting the inverted properties to the seismic response, the PEMs are used to maintain consistency between the time, depth and derived velocities throughout the inversion process. The proposed methodology overcomes the limitations faced by many existing techniques with regards to vertical resolution, time-to-depth conversion and the link between seismic response and reservoir properties. The result of our petrophysical seismic inversion is a fine-scale shared earth model in depth that is consistent with both log and seismic data and can be used for reservoir performance prediction.

After demonstrating the robustness of the method on synthetic data, we present a result from a real dataset. The proposed methodology has been successfully applied to porosity inversion on one of the largest undeveloped oil fields in the North Sea. A fine-scale reservoir model has been obtained which reveals previously undetected geological structures and leads to a better understanding of the reservoir zone.
Online Detection of Coiled Tubing Anomalies on a Small Scale for Safe CT Operations
Authors: Harbers P.
Published: December 2007

Since the combination of measuring fatigue and corrosion in one system would be ideal but not possible for now, the best way to ‘guard’ the coiled tubing's integrity before or during operation, is to detect corrosion or other anomalies in a very early stage. Calculations on form and depth of CT anomalies to predict its growth and behavior still turn out to be very difficult. This means online detecting on a very small scale would give you a better and immediate view on the growing speed of anomalies and thus your total decay of the CT string. ROSEN does this by means of her well-known knowledge in the Magnetic Flux Leakage principle and her 20+ years experience in pipeline inspections.

For Hibernia Canada we introduced a new feature in our software concentrating on corrosion finding and wall thickness. We have divided the wall thickness into 9 different wall thickness part sections around the circumference. This means a more precise indication (and therefore better resolution) of the wall thickness part (40° coverage each), which could contain a wall thinning including its clock position. Mechanical damage, corrosion parts or pits as small as approx 0.3mm (0.01″) in depth can now be detected!
World's First Utilisation of Coiled Tubing to Dissolve Hydrate(s) in a FPSO Riser: Case History
Authors: Ovesen M. , Laun L. , Varhaug H. , Nesvik K. T.
Published: December 2007

This paper is a case history of what is believed to be the first ever utilisation of Coiled Tubing on a FPSO (Floating Production Storage Offloading) vessel to dissolve hydrate(s) in the riser. The main focus of this paper is to: 1) Publish actual job results pertaining to friction factors (drag co-efficient) of the coiled tubing inside the FPSO riser.2) Highlight the innovative solution developed to allow for a possible emergency disconnection of the coiled tubing and CT Lubricator to allow the vessel to weathervane around the turret if required.3) Explain the technique used to dissolve the FPSO Riser hydrate(s).
Improving the Efficiency of Gas Storage Well Completions Using Underbalanced Drilling With Coiled Tubing
Authors: Weber J. , Stilson D. , McClatchie D. , Denton S. , King L.
Published: December 2007

A key element of maximizing injection and withdrawal rates in gas storage fields is minimizing skin damage of the completions. A highly efficient completion technique can reduce the number of storage wells required to produce and refill a storage zone. It also reduces the cost of installation and operation of the compression equipment required to achieve commercial injection and withdrawal rates. The current completion methodology involves conventional overbalanced drilling through to the target zone. Casing is run and cemented from TD with communication to the reservoir achieved by perforating. Skin damage is typically reduced by flowback and acid stimulation of the well to remove drilling mud and filter cake. A different approach utilizing underbalanced vertical deepening, or "well finishing" with coiled tubing was employed in the Huntsman Storage Field, Nebraska and the Sayre Storage Field, Oklahoma in an effort to further reduce skin damage. The wells were conventionally drilled and cased to the cap rock of the storage zone then the final stage of drilling to TD was performed underbalanced by a coiled tubing unit. The storage zone was completed openhole.
Do Complex Super-Gel Liquids Perform Better Than Simple Linear Liquids in Hole Cleaning With Coiled Tubing?
Authors: Li J. , Wilde G. , Crabtree A.
Published: December 2007

The properties of the circulation fluid have a fundamental effect on solids transport. The shear stress at the solids bed and liquid interface, for a near horizontal wellbore, plays the key role in transport of the solids. The flow regime, geometric combination of hole/coiled tubing (CT) and eccentricity, also effect the rheological state of the liquid and have a significant impact on the solids transport efficiency. There is a need to differentiate between the superior solids suspension capabilities of the liquid and its hole cleaning efficiency produced when it is in motion. The most important concept is that, the greater the solids carrying capacity a fluid has, the more efficiently the hole can be cleaned. The challenge that presents itself is that once the solids fall and form a bed within the wellbore, how can the solids be re-entrained and transported out of the hole?

In this paper, solids transport studies with several bio-polymers were conducted with a sophisticated flow loop. These studies highlight that these types of fluids bring some advantages and disadvantages. The carrying capacity and suspension properties of these fluids are superior but were hindered by other geometric influences on the velocity profile. Solids entrainment and re-entrainment into the fluid, as would be expected, is difficult to achieve without mechanical assistance. However, excellent efficiency of the fluid can be obtained and this paper presents some of the conditions under which this is practically achieved.
Effect of Particle Density and Size on Solids Transport and Hole Cleaning With Coiled Tubing
Authors: Li J. , Wilde G.
Published: December 2007

Particulate material to be removed from a wellbore can have a vast range in size and density. Typical materials are formation sand, drilling cuttings and various fracture proppants such as resin-coated sands, ceramics, Bauxite and ultra light-weight materials. The characteristic size, shape and density of the particles greatly influence their dynamic behavior in flowing media. Terminal velocity, drag and gravity forces and shear stresses are affected by particle properties and the rheology of the circulation fluid.

This paper presents the results of a solids transport study on four different density proppants with same particle size (20/40 mesh) and three different diameter particles ranging from 0.15 to 7 mm. The specific gravity of the proppants varied from 1.25 to 3.6. The tests were performed using a sophisticated flow loop. Findings indicate that particle density and size have a significant effect on the solids transport. For a given flow rate, higher density solids result in higher in-situ solids concentrations and lower wiper trip speed (the wiper trip speed is the coiled tubing pull-out-of-hole (POOH) speed) and reduced transport efficiency. The solids transport for different particle sizes is strongly influenced by wellbore deviation angle. In a near-vertical wellbore larger particles have the lower transport efficiency while in a horizontal wellbore the medium sized particles have the lowest transport efficiency.

New correlations have been developed from the experimental data to predict solids in-situ concentration, solids carrying capacity and optimum wiper trip speed for these tested solids under a given operating condition.
A Novel Method Using Coiled Tubing for Dewatering Gas Wells
Authors: Misselbrook J. , Falk K.
Published: December 2007

This paper will present an entirely new process for de-watering gas wells with liquid loading problems. The process removes produced liquids via a separate flow path and allows gas production unhindered by any liquid head. The result is higher gas production rates arising from increased draw-down and a reduction of near well-bore liquid saturation. An important additional benefit is ability to produce these wells at significantly lower flowing bottomhole pressures, resulting in an increase in recoverable reserves.
Unique Drilling Waste Handling and Transport System Offers Advantages to Drilling Operations and Assists Operators in Acheiving Safety and Environmental Compliance
Authors: Morris R. , Seaton S.
Published: December 2007

Since the introduction of various environmental regulations limiting or banning the discharge of various types of drilling fluids and associated drill cuttings globally, there has been considerable growth in what has become known as "zero discharge" or "ship to shore" operations. In these operations drill cuttings and associated waste fluids are collected on the rig in cuttings boxes (also known as skips) and then sent back to shore for disposal or treatment prior to disposal. In other situations, depending on local legislation, drill cuttings are collected and then transported to a grinding and slurrification package prior to injection downhole.1,2 In addition, even where the discharge of cuttings offshore is still permitted, there is often now a requirement to collect and transport drill cuttings on the rig for secondary treatment such as cuttings dryers that reduce the amount of drilling fluid associated with cuttings prior to discharge.3 These types of operations typically create operating challenges and additional costs associated with the required additional equipment, manpower, rig space, and in some cases, can even require significant rig modifications.

Various technologies have been used to date for the collection and transportation of drill cuttings. These include screw conveyors, vacuum systems, positive displacement pumps and pneumatic systems.4 The benefits and limitations of all of these systems are discussed in this paper with emphasis on the testing and performance of a positive displacement drill cuttings transfer system previously developed by Halliburton.

Depending on the technology used, there are safety and environmental risks associated with "ship to shore" operations and the use of cuttings boxes, such as significantly increased crane operations, housekeeping and deck space issues, transfer of wastes to boats or barges, the use of screw conveyors or high pressure pumping equipment and increases in waste volumes generated and eventually disposed of.
Measurements of PM2.5 Mass and Species Emissions from Natural Gas-Fired Reciprocating Internal Combustion Engines
Authors: England G. C. , Loos K. , Ritter K.
Published: December 2007

Innovative particulate emission measurements were performed on three different natural gas-fired spark-ignited reciprocating internal combustion engines at a natural gas production facility:A 4-stroke rich burn (4SRB) engine equipped with non-selective catalytic reduction for emissions control.A 4-stroke lean burn (4SLB) engine with no emission controls.A 2-stroke lean burn (2SLB) engine equipped with precombustion chambers for emissions control.

Emission measurements were made in the exhaust duct downstream of the engine and emissions controls systems using an innovative dilution sampling protocol and using traditional stationary source test methods with hot filters/iced impingers. A compact dilution sampler design, intended to be practical for routine stationary source stack emissions sampling, embodies the concept of dilution followed by aging developed by others, but with faster mixing, shorter residence time and lower sample flow rate. A broad suite of speciation measurements was applied to determine chemical and physical characteristics of primary PM2.5 (particles smaller than 2.5 micrometers in aerodynamic diameter) and PM2.5 precursor emissions. PM2.5 mass, ions, elements, organic carbon (OC) and elemental carbon (EC), particulate carbon and precursor species and ultrafine particle size distribution were determined. PM2.5 mass concentration measured by dilution sampling is approximately half that measured by traditional hot filter/iced impinger methods, although the difference is not significant at the 95 percent confidence level due to the variability of the results. The results suggest potential for positive bias in the organic condensable particulate measurement by iced impinger methods. Particulate speciation results from the dilution sampler show 80 to 90 percent of PM2.5 emissions are accounted for by OC, with smaller amounts of iron (Fe), silica (Si) and other inorganic compounds, for the 4-stroke engines. OC accounted for 98 percent of PM2.5 for the 2-stroke engine. Only a small portion of the OC was accounted for by identified organic species, which is not surprising (e.g., Zheng et al., 2002; Schauer et al., 1996). Polycyclic aromatic hydrocarbon (PAH) measurements indicate more than 99 percent of the organic carbon is most likely due to semivolatile organic compounds (SVOC) other than PAH. Preliminary measurements of ultrafine particle size distribution show peak particle number concentrations in the diluted exhaust at 40 to 50 nanometers, and particles between 10 and 400 nanometers account for 7 to 49 percent of total PM2.5 mass.
Delivering Perforation Strings in Extended-Reach Wells With Coiled Tubing and Hydraulic Tractor
Authors: Moore N. B. , Krueger E. , Bloom D. , Mock P. W. , Veselka A.
Published: December 2007

A new enabling technology of delivering long perforation gun strings and logging equipment into Extended Reach (ER) Wells using coiled tubing assisted by an innovative all hydraulic tractor is presented. Recent operational experience at Chayvo Field in Sakhalin Island Russia on the first ER well illustrates the new capabilities of this approach that delivered coiled tubing strings into a 9,375 meter well, performing multiple perforations and logging operations. Pre-operations equipment qualification testing and downhole modeling methodology for the project are discussed. Sakhalin Island surface equipment and bottom hole assemblies are described along with operational experience and lessons learned that successfully delivered heavy payloads into distant reservoirs beyond coiled tubing lockup.
Modeling and Measuring Dynamic Well Intervention Stack Stress
Authors: Smalley E. , Newman K. , Stephens R.
Published: December 2007

This paper reports the field results obtained from application of a system that provides both pre-job modeling capabilities and real-time monitoring of maximum stress levels in the entire intervention stack, from the wellhead to the injector assembly. In addition, the paper documents the dynamic movement capabilities recently incorporated in the model and validation of the model calculations.
Frac Packing with Low Environmental Impact Hydraulic Fracturing Fluid Benefits the Operator
Authors: Baycroft P. D. , McElfresh P. M. , Crews J. B. , Spies B. , Wilson B. , Conrad M. , Blackman M.
Published: December 2007

Offshore operators and service companies are increasing concerned about the environmental aspects of their offshore operations. Many offshore completions utilize "frac packing" as a preferred method to complete the soft formations found in the Gulf of Mexico. The frac pack operation manufactures and pumps large volumes of stimulation fluids from the fracturing stimulation vessel into the well. Most operations require at least two work string volumes of fracturing fluid to be reversed out and disposed of. This paper presents the development of a hydraulic fracturing fluid that not only met the oil and grease criteria established for well treatment fluids, completion and workover fluids; but how it was developed to meet the tighter standard established for the discharge of water based drilling fluids to comply not only with the letter of the regulations but with the spirit of the regulations.

The service company specifications for the development of the low environmental impact fracturing fluid required not only it meet the oil and grease standard but also the toxicity standard for water based drilling mud and a biodegradability standard. The fluid development required it to meet the more stringent environmental standard, maintain its performance as a fracturing fluid and remain price competitive. The research process, the sourcing of new suppliers and the development of unique chemistry, with new patents, to accomplish the fluid development objectives are presented.

The environmental performance of the fluid saves disposal costs, minimizes well site logistics and reduces risks associated of an accidental spill to both the operator and Service Company. A case history of the use of the fluid in an environmentally sensitive area is discussed and how the low environmental impact fracturing fluid system enabled the operator to discharge the fluid saving on disposal costs.
Investigating Applicability of Vogel's IPR for Fractured Wells
Authors: Rueda J. I. , Zakharov A. , Mach J.
Published: December 2007

It is a common practice in the oil industry that production engineers use Vogel's correlation to correct the IPR curve below the bubble pressure for unfractured and fractured wells. However, there has not been a comprehensive investigation to ensure if the Vogel's correlation can be applied for fractured wells.

This paper presents a new correlation to build IPR curves or predict production performance below the bubble pressure for fractured wells. In order to investigate fractured well performance below bubble point, about 1,000 simulations runs were performed using well-refined size grid for several sets of relative permeability curves and PVT data. The simulation model has been validated against analytical solution. Those runs cover a big practical range of fracture penetration 0.1 to 1.0 and dimensionless fracture conductivities from 0.5 to 50. Steady state conditions were analyzed at this study. All the mechanisms that cause the difference between fractured well and radial flow performance below the bubble pressure has been also well studied and will be presented in this paper.

It was found that Vogel's correlation underestimates fractured well performance below bubble point. Vogel suggests a correction of AOF by 45% meanwhile the simulation results and new correlation show that the correction should be only 22%. Therefore, engineer could have an error of 43% using Vogel for estimating AOF for a fractured well.

Another finding of this study is that multiphase effect is dependent on fracture conductivity and almost independent on fracture penetration. Higher conductivity fractures has bigger gas banks therefore they are affected by multi-phase effect to greater extent than lower conductivity ones. The new correlation is now being used for different fields and better fits the data than Vogel's correlation.
Impact of Completion Fluids on Productivity in Gas/Condensate Reservoirs
Authors: Al-Anazi H. A. , Okasha T. M. , Haas M. D. , Ginest N. H. , Al-Faifi M. G.
Published: December 2007

Gas wells in tight reservoirs have shown low gas deliverability after drilling and completion operations. This is partially attributed to penetration of completion fluids into the near the wellbore. This increase of liquid saturation into the reservoir can play a significant role in the blocking of tight rock due to high capillary forces and vapor pressure. The scope of this study was to investigate the impact of completion fluids on gas productivity in carbonate and sandstone reservoirs, and to evaluate feasibility of using various solvents to remove and/or minimize liquid blocking effects. In this study, extensive coreflood experiments were conducted on carbonate and sandstone cores recovered from gas reservoirs in Saudi Arabia to assess the loss in gas relative permeability caused by several fluids used as completion fluids. Alcohols were also evaluated as solvents to remove or minimize water blockage. Interfacial tension of fluids was measured using the pendent drop method at reservoir conditions. Experimental results showed that the used completion fluids (brines, KCl, alcoholic brines, and diesel) caused a severe reduction in gas productivity. The clean-up of these fluids was found to be a very slow process and is a function of capillary forces. Neat diesel caused a decline in the gas productivity index (PI) more than brine because it has a lower mobility. The solvents used were effective in displacing the completion fluids studied and consequently restoring gas productivity. Mixing brine with alcohol speedup the cleanup of trapped liquids.
Measurement of In-Situ Cuttings Concentrations Using Nuclear Densitometers in a Horizontal Annulus at Simulated Downhole Conditions
Authors: Zhou L. , Ahmed R. M. , Miska S. Z. , Takach N. E. , Yu M. , Pickell M. B.
Published: December 2007

This study presents experimental results and techniques that are developed for measuring in-situ cuttings concentration using nuclear densitometers under dynamic conditions. One of the key problems in borehole hydraulics and cuttings transport is the determination of in-situ cuttings concentration in the borehole while drilling. In order to investigate cuttings transport efficiency with aerated fluids under elevated pressure and temperature conditions, in-situ cuttings concentrations were measured manually (i.e. by flushing out the cuttings into a container and weighing them) and using nuclear densitometers. In-situ cuttings concentrations that were obtained using these two different measuring methods are compared and discussed. The results show good agreement between densitometer readings and cuttings weight measurements. This study is useful for designing in-line monitoring systems that accurately measure the cuttings concentration in drilling applications.
Stripper Gas-Well Production-Optimization and Reserve Retention
Authors: Gaskill Robert A.
Published: December 2007

The Effect of gas-water content phase behavior on mature methane rich gas wells has been investigated and found to be extremely detrimental. The wells performance becomes stressed and ultimate operating reserves will deviate negatively to previously established developed reserves due to fluid loading. The fluid loading phenomenon is usually associated with a gas production rate falling below the minimum mist flow rate required for the existing wells, producing tubular geometry. This analysis presents a method to reverse the ill effects of down hole phase behavior and suggest an alternate lift option. The advantage of this method is that it normally requires little or no down hole reconfiguration, and successful application would be superior to current artificial fluid lift operations. The resultant would translate to restoration or original developed reserves and quite possibly enhance production rate.

Scenario

It is only recently within the oil and gas industry history, that the concept of stripper gas well production has been recognized and addressed. The enhancement and retention of natural gas production has largely been secondary or non-existent compared to the new technologies directed toward the development of advanced oil recovery techniques. However, the future of natural gas has rocketed to the forefront of valued energy commodities. This is a result of its continued and prolific trend increase in demand. Natural gas has become the environmentally preferred fuel to meet future domestic power requirements. The efficient production and protection of established reserves has become of paramount value and importance in the light of national energy security and economic interests. Industry and attendant governmental agencies are now working in concert to address this issue and have successfully supported new and improved lifting technology.

Problem

A detrimental phenomenon exists within dry methane rich gas areas. That is, those natural gas reservoirs that might be described as low water saturation and devoid of any free water, or liquid hydrocarbon production throughout their early life. Mature production, invariably, commences to show signs of fluid loading. Hence, an operator will make attempts to counteract this performance by some mechanical adjustments. Pumping units, plunger lifts, downsized tubular, down-hole separators and soap sticks, are some of the common response strategies. All may off temporary, but not necessarily sustained relief. The operator's ultimate inability to cope with this phenomenon, however, usually results in the premature abandonment of the individual well and loss of developed gas reserves.
Improved Permeability Equation From the Bundle-of-Leaky-Capillary-Tubes Model
Authors: Civan F.
Published: December 2007

There is no consensus about the proper theory and equation of permeability of porous media in spite of the numerous investigations conducted to date. Many different expressions have been proposed in the literature for permeability prediction and/or correlation. The presently available and frequently used models, including the popular Kozeny-Carman equation, have certain limitations and are inadequate for applications involving the geological porous media. The bottom-line question is just what is the equation of permeability of the geological porous formations?

This paper provides some insights into the relationship of the porosity and permeability. The bundle of leaky capillary hydraulic tubes with cross-flow model of porous media by Civan1-7 is shown to alleviate the deficiencies of the present models. This model adequately approximates the actual flow schemes in porous media because it allows for interactions between the capillary hydraulic paths. The porosity-permeability data of various core samples are analyzed with this model. It is demonstrated that the power law exponent of the leaky-tube model deviates significantly from the unity. Therefore, the Kozeny-Carman8-9 equation having a constant exponent of unity cannot describe such core data.
Rheology and Hydraulics of Polymer (HEC) Based Drilling Foams at Ambient Temperature Conditions
Authors: Chen Z. , Ahmed R. M. , Miska S. Z. , Takach N. E. , Yu M. , Pickell M. B.
Published: December 2007

An experimental investigation on polymer-based drilling foams was carried out. Rheology tests were performed with foams that have different concentrations of Hydroxylethylcellulose (HEC) and 1% commercial surfactant. Experiments were conducted in a large-scale flow loop that permits foam flow through 2", 3" and 4" pipe sections, and a 6"×3.5" annular section. During the experiments, frictional pressure losses across the pipe and annular sections were measured for different gas/liquid flow rates, polymer concentrations (0%, 0.25% and 0.5%) and foam qualities (70%, 80% and 90%). Significant rheological variations were observed between aqueous foams containing no polymers and polymer-thickened foams.

Experimental data show three distinct flow curves for the 2", 3" and 4" pipe sections, which indicates the presence of wall slip. The Oldroyd-Jastrzebski approach was used to calculate the wall slip velocity and determine the true shear rate. It has been found that wall slip decreases as the foam quality or polymer concentration increases. Two foam hydraulic models, which use slip-corrected and slip-uncorrected rheological parameters, have been proposed. These models are applicable for predicting pressure loss in pipes and annuli. Model predictions for the annular test section are compared with the measured data. A satisfactory agreement between the model predictions and measured data is obtained. This paper will help to better design foam drilling and cleanup operations.
Federal Lands Access Inventories Conducted Under the Energy Policy and Conservation Act (EPCA) Amendments of 2000
Authors: Watson R. L.
Published: December 2007

The availability of onshore Federal lands for oil and gas exploration and production is the subject of a polarized debate. Industry interests claim that an excessive amount of Federal land is locked up; environmental interests assert that almost all the public lands are available for oil and gas leasing with few restrictions. The EPCA inventory represents an effort to supply a quantitative assessment of the situation.
Should Horizontal Sections be Cemented and how to Maximize Value
Authors: Ilseng J. R. , Hoskins L. R. , Matthews H. L. , Fuller G. A. , Pronger D. , Ravi K.
Published: December 2007

Development of marginal fields offers unique challenges during drilling, completion, stimulation, and production. The underlying objective should be to maximize the value of the field over its productive lifetime. Every phase of the well construction needs to be fully evaluated for subsequent impact on the safety and economics of producing oil and gas from the field. Log evaluation of formation type, thickness, and characteristics may determine the final completion plan, although lack of natural barriers from close water contact may be of major concern when a large stimulation program is required. Specialized low-density cementing systems may be necessary for maintaining satisfactory equivalent circulating density (ECD) for coverage across weak formations. These low-density systems can be prepared either by an engineered foaming operation or by the use of specialized additives blended with cement to lower the density, but production quality properties should be maintained. Consideration should also be given to the final cement sheath properties, which can provide isolation for the "life of well" following cyclic pressure loading from stimulation, testing, and flowing phases.

This paper addresses the advantages and disadvantages of the historical approach to constructing and producing horizontals. Completion processes and procedures with emphasis on cementation designs and best practices for horizontal casing are presented with major focus on resulting production rates. These case histories will cover both cemented and uncemented producing wells. Also included will be new methods for predicting cement failure modes as a result of cyclic pressure loading from stimulation jobs. Recent design procedures and ensuing effect for maximum value of the producing asset for life of the field will be compared with historical procedures.
A Unified Approach for the Removal of Barium Sulfate Scale Using Coiled Tubing
Authors: Boudreaux C. D. , Falk K.
Published: December 2007

Removal of scale depositions from wellbore tubulars has always posed a challenge to operators. Traditional methods to do so have included chemical treatments, mechanical methods, or even removal of affected tubulars. All of these methods have varying degrees of success, as well as varying cost to operators depending on the type and amount of deposition in the tubulars.

Barium Sulfate scale removal has traditionally posed the greatest challenge to operators and service companies alike. Chemical soaks have been developed and applied as well as mechanical methods, usually meeting with limited success. As a result of these failures, a dependable, engineered and cost effective approach has been developed. The process combines the use of traditional coiled tubing operations and a high-pressure rotary jetting tool to remove the Barium Sulfate scale – without use of solvents. The process has been successfully utilized to completely remove over 9,000’ of Barium Sulfate scale in subject wells that have not been effectively cleaned when tradition methods have been tried.

This paper will look at well conditions conducive to the formation of barium sulfate scale, as well as why it is such a difficult material to remove. Coiled tubing solutions will be discussed, culminating in a collection of case histories where a unified mechanical / jetting program has had best results.
Constructed Treatment Wetland Plant Monitoring Parameters
Authors: Myers J. E. , Nijhawan N.
Published: December 2007

When testing and evaluating constructed treatment wetland (CTW) performance, there is a tendency to focus on monitoring parameters for wastewater kinetics to meet discharge limits or water re-use standards, while the plant monitoring parameters (metrics) are neglected. This paper identifies six useful plant metrics, describes the plant monitoring methods, relates the parameters to CTW performance and assessment, and provides typical value ranges for parameters of plants commonly used in CTWs. Plant data are from pilot and full-scale CTWs, natural wetlands, and literature.
Don't Break the Wellhead
Authors: Portman L. , Crabtree A.
Published: December 2007

Drilling and workover rigs use a drawworks to pull up on the tubulars deployed into a well. The drawworks is attached to a mast or derrick, which in turn is supported by the ground or a floating vessel. The tubular's weight is not transferred to the wellhead.

Coiled Tubing uses an injector head, instead of a drawworks, to pull and push tubing in and out of a well. The injector is generally mounted directly onto the wellhead, unavoidably transferring some of the reactive loads to the wellhead.

These loads can be very substantial. They not only include the tubing's weight in the well but also loads generated by the Coiled Tubing on surface, that tubing which is being bent and pulled sideways. Often additional support is required to at least partially isolate these loads from the wellhead. This paper identifies the various loads that Coiled Tubing imparts to a wellhead and how support mechanisms provide protection to the wellhead.