bluuebunny/crossref_metadata_2025 huggingface dataset:
HPHT Drilling and Completion Design for the Erskine Field
Authors: Elliott G. S. , Brockman R. A. , Shivers R. M.
Published: December 2007

This paper summarises the factors influencing the well design for a high pressure high temperature (HPHT)* field development using a Not Normally Manned Installation (NNMI) in the UK sector of the Central North Sea (CNS).
Partnering and Alliances: Theory and Practice
Authors: Green Richard L.
Published: December 2007

This paper outlines some of the theories associated with the development of collaborative relationships (partnering and alliances) between companies which have shared objectives. It then reviews research carried out at The Robert Gordon University on relationships between operators and their contractors in the United Kingdom Continental Shelf (UKCS) Oil and Gas Production Industry. Basic data has been collected on 175 relationship and more detailed data has been obtained on about 20 relationships by interviewing the people involved. There is a wide variety of relationships in place in the industry and they are at differing stages of development. Views on the benefits and practicality of collaboration vary across the industry. By and large, comments received from the people involved in creating and managing collaborative relationships confirm the messages arising from the theory. The importance of behaviour and attitudes of the people involved at all levels is emphasised.

There is uncertainty and concern among the smaller contracting companies about how the market is evolving and how to react to it. Current theory does not appear to provide much assistance with this problem. There is also concern that the current developments can lead to a stifling of innovation among the smaller companies. The paper summarises the comments received on this subject.
The Harding Field: A Low Development Cost per Barrel Concept Becomes a Reality
Authors: Smith S. L.
Published: December 2007

BP's Harding Development employs a totally innovative concept for North Sea oil production. A large permanently insUiiicCi jack-up platform, incorporating production, drilling and living quarters facilities, is positioned on top of a concrete gravity storage base tank which holds Harding's acidic heavy crude before export, via a submerged turret loading buoy, to shuttle tankers. The use of horizontal drilling techniques in the early 1990's coupled with adoption of the above concept transformed a very marginal prospect into a viable development which currently has one of the lowest development costs per barrel in the North Sea.

The paper describes how the viability of the development has been achieved using an entirely new approach to project management by BP with a small integrated management team. The relationships created with design contractors, suppliers and fabricators are shown to represent the embodiment of the principles of the CRINE initiative and have secured for all parties benefits which can be used as benchmarks for future projects in a low oil price environment. Contractual arrangements are discussed and a new approach to Operations and Maintenance support contractors is highlighted.

The concept has potential for reducing abandonment costs due to the relative ease of decommissioning and removal.
Whole Life Cost Joint Industry Project
Authors: Crabb J.
Published: December 2007

Background

There is a growing awareness that Whole Life Costing (WLC) principles offer benefits in assessing the cost of projects, facilities and equipment before commitments are made. As a management tool they provide for options to be compared and for system cost-effectiveness and value-for-money to be optimised.

Properly understood and applied, WLC principles provide a powerful analytical capability: coupled with logistic support and economic analysis techniques they provide the means by which cost drivers and dependencies can be identified, targeted and more effectively managed.

Current Status

Although individual operators have started to apply WLC principles as part of their own development studies, advancement has been constrained. This is mainly due to different interpretations of WLC methods, techniques and requirements.
Design Principles and Material Failures During Operation
Authors: Strandmyr Ø. , Bakken K. A.
Published: December 2007

Corrosion failures in piping systems and associated equipment on offshore platforms cost our Company multimillion US dollars per year.

There are many different reasons for the corrosion failures. This paper will discuss some of the factors related to design and how these design parameters are met during the operating phase. Concrete examples from Statoil operated offshore platforms illustrate some typical corrosion failures.

Many actions have been taken to improve the engineering phase involving material selection. Communication between involved disciplines and representatives from operating departments and end users have been improved with socalled integrated project teams. At the same time has work been done to improve the design basis.

The ultimate goal is to reduce capital costs and costs during operation and at the same time operate to the highest safety standard.
Evaluation of Compact Steam/Water Separation Equipment for Gas/Oil Systems
Authors: Birmingham D. P. , Davies S. R.
Published: December 2007

The possibility of using existing steam/water separation equipment for compact gas/oil separation applications has been evaluated and is believed feasible.

A single separator pair operating at 880 psia is estimated to have a separation capacity of 28,000 BPD oil and 15 MMSCFD gas for a water drive reservoir, and 17,000 BPD oil and 15 MMSCFD gas for a gas drive reservoir. Larger capacities are expected at lower pressure. Efficient separation is expected over a wide range of flows, liquid levels, and pressures. The vertical orientation of the separator allows it to be contained within a 24-inch diameter pressure vessel.

Potential areas where this compact separation equipment may be beneficial include primary separation for minimum facility platforms, vertical high pressure gas/liquid separation, retrofit/add-on capacity, combined slug suppression and preseparation, gas/liquid separation for floating production systems and subsea applications. The major benefits are expected to be its compactness, small footprint and weight, and the modularity of the design.
Reduction of Cost with New Well Intervention Technology, Well Tractors
Authors: Hallundbæk Jørgen
Published: December 2007

We have successfully tested a new concept for a down hole tool, a Well Tractor, that significantly reduces operation costs for servicing horizontal wells. The Well Tractor is a cost effective alternative to the very expensive and time consuming conventional drill pipe conveyed operations.

In general the Well Tractor is capable of pulling coiled tubing and/or wireline horizontally beyond 10,000 ft. The Well Tractor is capable of pulling more then 25,000 ft of coiled tubing and/or wireline into a highly deviated well. Furthermore the tool is designed for pushing other tools into the hole, e.g. logging tools, video cameras. The lateral reach capacity with coiled tubing is therefore increased considerably. Time consuming production logging operations of horizontal wells utilising jointed pipe can be carried out by the Well Tractor as a wireline job.

We have tested the Well Tractor for cleaning horizontal wells. We have run production logs, we have performed test with running of a tool string with 40 ft. long perforation guns. We have set bridge plugs with a safe ignition system and we have retrieved the plugs again with a Well Tractor.

Apart from the mentioned applications the Well Tractors can also be used for operating sliding sleeves, open hole logging and coiled tubing drilling etc.

The Well Tractor with modular power source is designed in two versions. A fluid driven version for coiled tubing operations and an electric driven version of the Well Tractor for wireline operations
Deployment Systems and Down Hole Swab Valves
Authors: Sharman D. M. , Pettitt A. J.
Published: December 2007

A deployment system has been developed which allows for the insertion of any length of Bottom Hole Assembly (BHA) both into and out of wells, under pressure. Simultaneously a Down Hole Swab Valve (DHSV) has been developed which also permits the insertion of long BHAs into live wells. These developments mean that the lubricator height is no longer the limiting factor for the length of a BHA. These techniques can be applied to: Long perforating gunsLong logging toolsRunning screens or other completion components into live wells

The deployment system has been used in the field to run 910 ft of 2-7/8" perforating guns into a horizontal well in the Dutch sector of the North Sea. The first use of the DHSV is anticipated in a multilateral well in the Danish sector of the North Sea.

The debut for both systems was intended for perforating a well in the British sector of the North Sea. This paper explains the process of evaluation, selection, development and testing of both systems. The relative applicability of each system is discussed.
Operations Support Vessel for Liverpool Bay Development
Authors: McCurley Mark , Summers James L. , O'Callaghan Michael J.
Published: December 2007

Operational support functions are an important consideration in the development of offshore reserves and must be administered in such a manner that prevailing environmental regulations, personnel safety, and the local environment are not compromised. At the same time, the economic burdens imposed by their administration must be compatible with production forecasts.

This paper will discuss a unique support approach that was codeveloped by BHP Petroleum Limited (BHP) and the engineering staff of an international oilfield servicing/ manufacturing company to support the operational objectives for the Hamilton, Hamilton North, Douglas, and Lennox fields in the Liverpool Bay Development. A key component of the concept is a manned, self-elevating Operations Support Vessel (OSV) that can provide cost-efficient infield service to the offshore platforms in the developed locations while maintaining all safety and environmental requirements.

The OSV concept has enabled the operator to develop fields in shallow water with unmanned, minimum-facility, standardized platforms that are consistent with the industry "Cost Reduction in the New Era" (CRINE) initiative. When multiple fields are within reasonable proximity, the economic advantage gained with this vessel is enhanced even further.

The success of this approach brings a cost effective solution to the development of offshore reserves in shallow waters that cannot support the economic burdens of traditional North Sea manned platform designs. This approach to field development for the UKCS has resulted in a life-cycle operating contract between BHP and the servicing company. This interaction has not only enhanced current operational technology within the required parameters but also illustrates a practical example of an industry "win-win" relationship.
Full Scale Kick Detection System Testing Relevant for Slim-Hole / HPHT Drilling
Authors: Steine Otto Gams , Rommetveit Rolv , Harris T. W. R.
Published: December 2007

During June 1994 tests in the project "HPHT Kick Detection System Testing" were performed in Ullrigg well U-2.

Experimental parameters such as influx type (liquid/ gas), gas concentration, kick injection rate, flow rate, rpm's, pipe reciprocation, pump speed changes, etc. were varied. Three kick detection systems were operating during the experiments. Two delta flow systems were supplied by Baker Hughes INTEQ (DrillByte "Kick detect" and "KDS") and one acoustic system was provided by Smedvig (Gas Kick Warner). In addition, the Petreco J-Meter flow out measuring device was also tested.

A total number of 14 kicks were performed during these experiments. The majority of kicks were performed at slim hole conditions.

Raw data files containing approx. 14 Mbytes of downhole pressure data from bottom P-sensor, and surface data have been gathered for further analysis. The data was of high quality and provide opportunities to improve existing well control procedures and to incorporate this knowledge into future drilling operations.

This paper summarises the experimental conditions during which data were recorded, main results and operational recommendations.

GAS INJECTION – STARTS.
An Experimental Study on Fluid-Loss Behavior of Fracturing Fluids and Formation Damage in High-Permeability Porous Media
Authors: Parlar M. , Nelson E. B. , Walton I. C. , Park E. , DeBonis V.
Published: December 2007

A recent trend in stimulating high-permeability formations is the development of techniques (such as frac-pack) to create short fractures which bypass formation damage in the near-wellbore region. Analysis and refinement of these techniques are hampered by a lack of knowledge of the leakoff behavior of candidate fluids in high-permeability rocks. In this paper, we present results from static-fluid-loss and formation-damage (reverse-flow) experiments using 12-inch-long cores in the permeability range of 3 to 1,000 md. A Hassler cell, with 6 pressure taps placed at 2-inch intervals, was used. The test fluids included borate-crosslinked-guar, linear-guar, linear-HEC, and viscoelastic-surfactant solutions. The effects of differential pressure, gel concentration, permeability, and temperature on spurt and leakoff coefficients were investigated, and correlations were given. In the absence of fluid-loss-control additives, the internal cake is the controlling factor for spurt and total leakoff for crosslinked fluids. Linear HEC behaves as a shear-thinning fluid during flow through porous media. A nonlinear, algebraic equation generalizing the well-known Williams expression for Cvo to power-law fluids was derived as an approximate method of incorporating the leakoff behavior of power-law fluids into current fracturing simulators.
Oil Pollution Incidents in the Southeast - Damage, Cleanup, and Future Control
Authors: Little John A. , Smith Al
Published: December 2007

Many in the water pollution control field have tired of hearing the names Torrey Canon and Santa Barbara. Certainly these names do bring to mind the most notorious of the oil spills. We must not forget, however, that both of these events have helped to provide the impetus to prevent and control oil spills. prevent and control oil spills. Since the Torrey Canyon disaster in March 1967, the incidence of spills in the United States, both extensive and minor, has been on the rise. This rise cannot be attributed solely to the increase in reporting oil spills. There are simply more of them. Soon after completion of his recent historic voyage across the Atlantic, Thor Heyerdahl revealed that petroleum-base residues litter the seas from coast to coast. We all know, then, that there is a serious problem, and it is gratifying to note problem, and it is gratifying to note the voluntary efforts on the part of the petroleum industry to correct this problem. petroleum industry to correct this problem. It might be added that your industry was proceeding to research means for abating proceeding to research means for abating oil pollution well before the stiff fines provided for in the 1970 Water Quality provided for in the 1970 Water Quality Improvement Act were enacted into law.

Another statement which can be made at this time, and one which borders on triteness, is that many more improvements remain to be made in this country's overall efforts to control oil pollution. One way to effect improvement is to promote a free exchange of ideas among promote a free exchange of ideas among people who are concerned and/or are people who are concerned and/or are knowledgeable in this field. Meetings such as this provide a forum for this information exchange.

The intent of this paper is to report on some of the oil spill incidents which have occurred within the Southeast Region, Federal Water Quality Administration (FWQA). For whether the reason—extensive coastline, number of petrochemical product manufacturers or users, number of pipelines traversing, etc.—the Southeast Region, FWQA, has had its share of oil spills. Two such spills will be mentioned here in some detail—one a coastal spill and one inland.

On March 3, 1968, almost one year after Torrey Canyon the tanker, Ocean Eagle, broke apart at the entrance to San Juan Bay in Puerto Rico. For the next several weeks, Federal, Commonwealth, and private groups fought the most severe oil spill experienced in U. S. territorial waters up until that time.
Application of a Highly Variable Gauge Stabilizer at Wytch Farm to Extend the ERD Envelope
Authors: Odell A. C. , Payne M. L. , Cocking D. A.
Published: December 2007

Wytch Farm operations have demonstrated that downhole adjustable, highly variable gauge stabilizers (HVGSs) can cost-effectively extend the reach of extended-reach-drilling (ERD) wells. This paper will describe the operation and benefits of using an HVGS at the Wytch Farm ERD project to control hole inclination while minimizing time consuming oriented drilling. The first Wytch Farm well drilled with an HVGS had a Reach/TVD ratio of 4.22 at a true vertical depth (WD) of 1603 m, The total depth was 7522 m with a reach of 6732 m, which set a new world record for reach at the subject reservoir depth. The second well drilled with an HVGS had a Reach/TVD ratio of 4.28 at a TVD of 1592 m. The HVGS was used in conjunction with an instrumented steerable motor with near-bit inclination sensor. The HVGS is controlled from the surface through a series of mud pump flow sequences, and communicates the blades' commanded and measured positions to the surface with mud pulse telemetry. Wytch Farm operations required that the HVGS telemetry be modified to allow compatibility with previously contracted measurement-while-drilling/logging-while-drilling (MWD/LWD) systems. This paper will describe the new telemetry scheme and will document the success of the HVGS in receiving commands and in actuating to desired positions at measured depths in excess of 7300 m and departures beyond 6100 m.
Rolling Cone Bits with Novel Gauge Cutting Structure Drill Faster, More Efficiently
Authors: Pessier Rudolf C.O. , Grimes Robert E. , Isbell Matthew R. , Scott Danny E.
Published: December 2007

Roller cone bit design practices that focus on improving gauge durability have resulted in heavily reinforced and rugged, but highly inefficient, cutting structures.

This dilemma prompted an in-depth study of the cutting mechanics in the corner of the borehole. The study consisted of a review of gauge cutting structure design and kinematics, laboratory testing with individual cutting elements to determine cutting forces and full-scale simulator and field tests,

The work not only confirmed the original supposition, but led to the development of a novel, patented gauge cutting structure that is more aggressive, faster, and at least as durable and wear resistant as conventional designs.
Simultaneous Drilling and Reaming with Fixed Blade Reamers
Authors: Warren T. M. , Sinor L. A. , Dykstra M. W.
Published: December 2007

Deep well drilling programs often require the use of multiple casings or liners. Designing these wells require compromises between using the smallest surface hole possible to minimize tubular costs and maintaining the largest hole possible to allow for contingencies and for the optimum completion design. The conflict between these two considerations can be resolved somewhat by nesting the casing strings with the minimum clearance between them. Unfortunately this often requires that the section drilled below a casing string be reamed to a larger diameter than the casing ID. The reaming process is often fraught with many inefficiencies. This paper describes a technique for simultaneously drilling and reaming with a bi-center reamer run on a stabilized assembly above a pilot bit. The successful use of the technique in three field wells is reported.
High-Power Slim-Hole Drilling System
Authors: Cohen John H. , Maurer William C. , Leitko Curtis E.
Published: December 2007

Economic conditions in the oil and gas industry have encouraged the use of new methods to reduce drilling costs. Slim-hole drilling, abandoned in the past, has found new life because it offers savings by reducing equipment size, tubular products, and environmental impact. A new high-power slim-hole drilling system has been developed that overcomes many of the problems that led to the abandonment of slim holes in the past. This new system is composed of a new high-power positive-displacement motor and new TSP bits developed to run at high horsepowers and produce high drilling rates. The new slim-hole system has the potential for reducing drilling costs by 40 to 60 percent.
Characterization of Breaker Efficiency Based upon Size Distribution of Polymeric Fragments
Authors: Brannon Harold D. , Pin Robert M. Tjon Joe
Published: December 2007

Damage to proppant packs is known to negatively impact well productivity. The damage is often the result of inadequate degradation of the polymers used to viscosify fracturing fluids. Gel breakers are used to degrade the polymer by cleaving the macro-molecule into smaller fragments, ideally to a size which can easily be produced during load recovery. Fluid viscosity reduction is commonly used to gauge polymer degradation. However, although viscosity reduction indicates polymer degradation, it is misleading to conclude that this reduced viscosity equates to improved fracture conductivity. Polymer fragments which are desolublized from the gelled fluid no longer contribute to fluid viscosity but do, unfortunately contribute significantly to proppant pack damage.

Several new breaker technologies have been introduced in efforts to improve polymer degradation, and hence, improve fracture conductivity and ultimately well productivity. Many production case histories have been offered as evidence of the utility of the new technologies to improve well productivity. However, the facility to quantitatively determine the polymer degrading efficiency of the breakers has heretofore been lacking. Laboratory procedures, both wet chemical and instrumental, have recently been developed to address characterization of the relative degrading efficiency of the various breakers and breaking mechanisms. The analysis of the combined data provide both a qualitative size distribution, as well as a quantitative profile of the polymer fragments. Extensive studies were conducted employing the new procedures to compare the degrading efficiency of various oxidative and enzymatic breakers. Detailed analysis of the results are provided.
An Investigation of Fluid Leakoff Phenomena Employing a High-Pressure Simulator
Authors: Lord David L. , Vinod P. S. , Shah Subhash , Bishop Milton L.
Published: December 2007

This paper describes the results of fluid-loss tests conducted with various hydraulic fracturing fluids through the use of a large-scale, high-temperature, high-pressure simulator (HPS) thai can perform dynamic fluid-loss experiments over a large surface area under 1,000 psi differential pressure. Nearly all fluid-loss studies previously reported in the literature have described laboratory tests involving small-core plugs having a surface area of approximately 11 cm2. In contrast, the fluid-loss data collected in the HPS are over a significantly larger surface area, approximately 3912 cm2.

Results from the HPS were compared to laboratory data, and significant differences in spurt-loss values were found. Surface texture was also found to be a significant factor in determining the extent of filter-cake formation. The paper provides insight into the differences between fluid-loss control mechanisms displayed by linear polymer solutions and crosslinked gels. Experiments specifically designed to evaluate various hypotheses were performed to determine the significance of external filter cake on fluid-loss control of crosslinked fluids. Conventional fracturing fluids and additives were found to be inefficient in controlling fluid loss to natural fractures in a rock matrix.
Theoretical Model and Numerical Investigation of Near-Wellbore Effects in Hydraulic Fracturing
Authors: Romero J. , Mack M. G. , Elbel J. L.
Published: December 2007

The high near-wellbore pressure drop which has frequently been reported in fracture treatments is indicative of ineffective communication between the wellbore and the fracture. Although numerous observations of such effects have been published, few attempts have been made to understand them. This paper describes three possible mechanisms of near-wellbore effects: perforation phasing misalignment-induced rock pinching, perforation pressure drop, and fracture reorientation (deviation tortuosity) – and their implementation in a numerical fracture simulator. Typical signatures of all three effects in fracture treatment records are shown, and a method proposed by which to distinguish them.

Perforation phasing misalignment has been identified as a cause of near-wellbore restriction. Because the fracture does not always initiate at the perforation, the fluid must communicate with the fracture through a narrow channel (micro-annulus) around the casing. The paper describes this pinching effect and shows that it is related to the contact stress between the cement and the formation.

Perforation pressure drop and deviation tortuosity, which have previously been proposed by other authors, have also been modeled. They have been incorporated in the simulator, together with the phasing misalignment effect, to allow investigation of the differences in response between the different mechanisms. Results of simulating the effects of erosion of near-well effects on treating pressure are also shown.
Down-Hole Water-Oil Separation and Water Reinjection Through Well Branches
Authors: Kjos T. , Sangesland S. , Michelet J. F. , Kleppe J.
Published: December 2007

Cyclone separation of oil, water and gas has created new possibilities for separation of fluids down-hole close to the producing formation and thus facilitating separation at generally more favourable conditions.

In this paper, alternative well configurations incorporating down-hole separation of oil and water are suggested and discussed in terms of costs and feasibility, and effects of down-hole separation on well flow performance and reservoir behavior are evaluated.

Potential effects of the new technology on reservoir behavior has been investigated on a hypothetical water coning reservoir. Reservoir behavior under dual completion above and below water-oil contact combined with water reinjection in the aquifer is compared to conventional coning behavior. Our results show that balancing of the water-oil contact is possible by dual completion.

By reinjection of the produced water far away from the production interval, the water displacement mechanism is maintained. By supplementing the produced water reinjection by external water, in order to enhance the water displacement, very high recoveries may be obtained.

Separation of oil and water down-hole may reduce the use of toxic chemicals in pipelines and a brief discussion of the topic is included.
A Rational Characterization of Proprietary High Collapse Casing Grades
Authors: Klementich Erich F.
Published: December 2007

An increasing number of users are finding it necessary to utilize "High Collapse" casing grades for deep set and intermediate size drilling and production casing strings. Unfortunately, the great variety of proprietary (non-API) high collapse casing grades has made it extremely difficult for drilling and completion engineers to logically select the optimum size, weight, and grade of pipe meeting the design objective, due to the wide variation in collapse resistance claims and the guaranteed pipe dimensional and mechanical properties supporting that claim. This paper provides a technically sound method for selecting and safely using high collapse pipe.
Characterization and Modeling of Channel and Thin-Bedded Turbidite Prospects in the Gulf of Mexico: Integration of Outcrops, Modern Analogs, and Subsurface Data
Authors: Shew R. D. , Tiller G. M. , Hackbarth C. J. , Rollins D. R. , White C. D.
Published: December 2007

Deep-water reservoirs composed of thin-bedded deposits or thin-bedded deposits with subordinate channel complexes have been penetrated throughout the Gulf of Mexico. These reservoirs are problematic to evaluate because conventional petrophysical and geophysical data cannot resolve their internal architectures and rock properties. Proper characterization and delineation of these types of reservoirs require detailed core analyses, analog studies, and multiple reservoir sensitivity and simulation studies in addition to high resolution log and seismic data. This paper focuses on the description and application of these techniques to the evaluation of two Gulf of Mexico reservoirs.
Field Tests of a New 2 MHz Resistivituy Tool for Formation-Evaluation While Drilling
Authors: Heysse Dale R. , Jackson Charles E. , Merchant G. A. , Jerabek Alois , Beste Randy , Mumby Edward
Published: December 2007

A new 2 MHz resistivity tool for logging-while-drilling (LWD) in slim holes has been developed and field-tested. The Slim Compensated Wave Resistivity* (SCWR*) provides four formation-evaluation resistivity measurements in all mud types and in boreholes as small as 5-7/8 inches. Dual transmitter-receiver spacings measuring both phase and attenuation produce four resistivities, sufficient to determine formation resistivity and evaluate invasion. Since many slim holes are drilled in lower-porosity reservoirs, where pay-zone resistivities are often higher than 20 ohm-m, the SCWR tool was designed to provide improved measurement accuracy at these higher resistivities. Similarly, slim holes tend to be hotter than larger boreholes, and the symmetrical design of the SCWR antenna array provides excellent temperature stability. Finally, slim holes are often associated with medium-radius drilling, so the SCWR tool was designed to operate reliably in wells with bends as great as 19°/100ft (rotating) or 36°/100ft (sliding).

Field tests have been conducted in a wide range of formation types and drilling conditions. These tests have been used to refine the mechanical design and antenna array, and have confirmed both measurement quality and reliability. This paper describes the features and capabilities of the SCWR tool, and presents several log examples from the field tests.
The Use of NMR Core Analysis in the Interpretation of Downhole NMR Logs
Authors: Brancolini A. , Gossenberg P. , Lyne A. , Mackenzie I. S. , Radaelli F.
Published: December 2007

Laboratory NMR measurements on core are particularly important for understanding NMR downhole logs from formations which have no NMR logging history. We have used low frequency (2MHz) NMR relaxation measurements on core plugs from a gas well in Southern Italy both to acquire petrophysical data and to clarify the interpretation of the downhole log.

In the cored interval the lithology is divided into thin sand and shale beds (<lm). Measurements on the core have provided the basis for extracting maximum useful information from the NMR downhole measurements which do not resolve the thin beds.

As part of a more general programme we have investigated the potential of NMR measurements on saturated core, from two wells in the field, as indirect predictors of other parameters of petrophysical interest such as irreducible water saturation and permeability.
Lithology-lndependent Gas Detection by Gradient-NMR Logging
Authors: Prammer M. G. , Mardon D. , Coates G. R. , Miller M. N.
Published: December 2007

It has been shown that the Magnetic Resonance Imaging Log (MRIL®) can detect hydrocarbon gases present in the near wellbore zone (approximately 10 cm from the borehole wall). By exploiting the T1- and diffusion-weighting capabilities of this tool, mineralogy-independent water and hydrocarbon saturations can be determined in this zone. Gas and oil saturations are used to correct the reduction in apparent NMR porosity, an effect due to reductions in hydrogen index and incomplete recovery of magnetization polarization.

The proposed method exploits the predictability of density, hydrogen index, T1 and diffusivity of the non-wetting phase from its bulk properties. Gas is always and oil is often non-wetting. The MRIL®/C’s multi-frequency capabilities are used to integrate changes in recovery time and/or echo spacing into a single logging pass. The resultant data streams are processed in the complex time-domain to extract signal components characteristic for hydrocarbons.
A Field Application of Multiple-Well Testing for Reservoir Characterization
Authors: Hallford Debora L. , Hegeman Peter S.
Published: December 2007

A multiple-well test was conducted in Oklahoma which enabled the identification of two separate reservoirs in a new field. Quantitative analysis of the test, including determination of well-to-well permeability and distances to reservoir boundaries, was done using an analytical multi-well reservoir simulator. The test results were used to help determine whether additional wells were needed to optimize primary recovery for the field.
High Resolution From a New Laterolog With Azimuthal Imaging
Authors: Smits J. W. , Benimeli D. , Dubourg I. , Faivre O. , Hoyle D. , Tourillon V. , Trouiller J-C. , Anderson B. I.
Published: December 2007

A new resistivity logging tool is described that improves the efficiency of drilling and logging operations by halving the length of traditional Dual Laterolog arrays to 16 ft. The reduced length and weight of the monolithic sonde lead to faster rig-up and can save several meters of rat-hole.

The array, based on the configuration of a Dual Laterolog and complemented by an azimuthal electrode array in the center, was designed for high vertical resolution and optimized for invasion response and borehole effect. The tool’s operation is based on a number of independent and simultaneous measurement modes that are combined by software to yield a series of resistivity measurements with different depths of investigation and resolutions.

The standard deep and shallow laterolog curves are output with improved resolution, but the flexible computed focusing also allows the substitution of different focusing conditions, which simultaneously yield deep and shallow resistivity curves with still higher resolutions of around 8 in. The passive azimuthal array at the center of the tool provides resistivity imaging of the formation in deep and shallow mode and an auxiliary ultra-shallow measurement sensitive to the radial distance from the borehole wall. An additional in-situ determination of the mud resistivity permits accurate realtime borehole corrections to be made.

Examples from recent field tests show the invasion and thin-bed response of the tool together with applications of the resistivity images.
Estimation of Producible and Remaining Oil Using High Frequency Dielectric Log in Carbonate Reservoirs
Authors: Chang D. , Myers M. T.
Published: December 2007

Producible and remaining oil volumes are essential for reservoir characterization and management We have used the EPT* (Electromagnetic Propagation Tool) to determine them. A dielectric dispersion model for carbonates based on laboratory measurements is introduced. The differences between this model which depends on pore geometry and previously published models are then demonstrated. EPT data is shown to be consistent with the pore geometry dependent dispersion implied by the model. Field applications of EPT logging to estimate remaining and producible oil saturations are shown for several West Texas carbonate reservoirs.
Correcting Measured Mechanical Properties for Size and Time Scale
Authors: Schatz J. F. , Truman R. B. , Schraufnagel R. A.
Published: December 2007

A model to correct for the size and time (frequency) scale variations of measured mechanical properties is presented. We show by comparing field data and laboratory data that large effects can occur. It follows that large errors can result from not making corrections to small size and/or high frequency measured values before using them in applications. The proposed model uses mathematically well-defined effective discontinuity distributions in the rock and a relatively small, measurable parameter set. The model does not use purely empirical correlatinns and therefore may be portable and accurate over larger extrapolation ranges. Log and core measurements for velocities and moduli should be adjusted before using them in applications such as in-situ stress estimation, hydraulic fracture design, wellbore stability or formation integrity calculations, and large-scale long-term formation deformation predictions.
In-Situ Residual Oil Saturation to Gas from Time-Lapse Borehole Gravity
Authors: Alixant Jean-Louis , Gabon Shell , Mann Ethan
Published: December 2007

Three time-lapse borehole gravity surveys were performed one year apart in the dedicated data gathering and monitoring well of the Rabi oil-rim. For the first time, time-lapse density logs derived from Borehole Gravity Meter (BHGM) runs are used to estimate residual oil saturation in-situ. This is also the first time that the BHGM is used to determine interval density at one meter spacing. This paper reviews the planning of the BHGM surveys, explains why it became necessary to reduce the survey intervals to one meter, highlights the enhancements that made such measurements possible, and presents the first residual oil saturation results.

BHGM density is derived from the gravity gradient measured between two survey depths. The accuracy of the BHGM density is therefore governed by the accuracy of both gravity and depth measurements. The uncertainty of the gravity difference between two survey depths was significantly reduced through sensor improvements and new processing techniques. Depth-related errors were practically eliminated using a "Shuttle Sonde" to accurately position the gravity sensor within intervals up to 2.5 m.

The time-lapse technique is immune to structural effects which can bias single BHGM surveys. In addition, the BHGM is latched into grooves built into the glass-reinforced Plexiglas (GRP) casing to ensure that the stationary tool is positioned exactly at the same depths from year to year.

The reproducibility of BHGM density measurements between different runs is ±0.015 g/cm3 (one-σ, i.e. one standard deviation confidence level) over one meter intervals. This level of accuracy had only been achieved over three meter intervals prior to the present survey, thereby suggesting a threefold increase in the vertical resolution of the BHGM density measurement. As a result, a first estimate of residual oil saturation to gas was determined from BHGM data after only two years to within ± 10 su (one-σ) on a one-meter survey interval. The remaining oil saturation to water estimate derived from time-lapse BHGM surveys is in close agreement with residual oil saturation to water interpreted from time-lapse PNC logs.
Multi-Step Geostatistical Modelling of a Complex Reservoir Based on Quantified Sedimentary Models and Characterization of Core Petrophysical Groups
Authors: Petit F. M. , Caline B. , Greder H. N. , Pellerin F. M. , Calatayud P. M.
Published: December 2007

This paper outlines a multi-step geostatistical methodology for constructing reservoir models using sedimentary data and the notion of Petrophysical Groups.

This method is illustrated through a case study of a mixed carbonate platform oil reservoir (a 20-meter thick sequence). Indeed the technique appears to be particularly suited for reservoirs with great variability of petrophysical properties characterized by a due to the combination of sedimentary and diagenetic effects.

The first stage is the construction of the sedimentary model, with a particular emphasis on the shapes, extents and vertical and areal development of sedimentary bodies.

The second stage consists in constructing Petrophysical Groups from core measurements through statistical clustering techniques. Each Petrophysical Group is a set of reservoir zones having similar porosity, permeability, grain density and capillary pressure curves. Water saturations and relative permeability functions can be assigned to Petrophysical Groups with good confidence.

In the third stage sedimentological and petrophysical data are reconciled in order to map reservoir properties. It appears that the organization of Petrophysical Groups within sedimentary bodies can be explained by depositional and post-depositional factors that may be assessed using well data and regional information. These relationships, once quantified, allow us to build the model of reservoir properties in three steps involving an object-modelling technique, the Sequential Indicator Simulation and Sequential Gaussian Simulation, respectively.

In this complex reservoir the method proves to be a powerful alternative to conventional approaches to the modelling of petrophysical heterogeneities which use lithofacies as a basis for the mapping of reservoir properties.
A Dynamic Simulator to Analyse and Remedy Gas Lift Problems
Authors: ter Avest D. , Oudeman P.
Published: December 2007

Gas lift efficiency is substantially affected by unstable behaviour of wells. Unstable production, or heading, results in prolonged periods of reduced or even vanishing production and therefore leads to significant oil deferment. Since heading can be caused by a large variety of factors, such as incorrect gas lift string design, improper valve setting, or valve leaking or plugging, it is often difficult to find the origin of the heading. To aid in the diagnosis of gas lift problems, a dynamic gas lift simulator was developed. The simulator computes the transient flow of gas and liquid through the production tubing. Valve models are used to calculate the passage of gas or workover fluid through the valves as a function of pressures local to the valves. The simulator is used to study poor lift gas performance, quantify the effect of remedial measures and optimise unloading procedures. Examples are given of field cases that were studied with the simulator.
Particulate Problem Solutions for Rod Pumped Producing Wells
Authors: Williams B. J.
Published: December 2007

Sand and other fluid entrained particulates can cause substantial operational problems for rod pumped producing wells. These problems take the form of down-hole pump wear, plunger sticking, and/or catastrophic breakage of pump components.

A six year study of 600+ pump investigations shows that problems with particulates account for a substantial number of the total barrel and plunger failures. Many of these failures could have been avoided through the proper application of API and special pump designs as well as certain choices of pump variables. These pump variables and designs will be addressed along with operating parameters.

How hard is sand? How large is it? Should plunger and barrel choices take these variables into account? Also, metal plungers must "slip" fluid for proper lubrication. Too much slippage leads to pump inefficiencies. However, down-hole pump efficiencies based on slippage need to be balanced against pump longevity due to proper selection for particulate production. Some time-proven roles of thumb can be applied to make these choices, and an included chart will make plunger slippage calculations simple and straightforward.

Scale which sticks to pump surfaces dictates the choice of a different style down-hole pump. A straightforward modification of an RH style API pump has proved successful in these conditions.

Fluid and particulate production with and without attendant gas production requires a different approach to down-hole pump selection. Several successful older pump designs as well as some recently proven new designs will be described.

A test program has been completed and actual applications have shown that an API Tubing Pump derivative can pump large volumes of particulate laden fluid without characteristic sticking of the plunger.
Experience from Topside and Subsea Use of the Erosion Based Sand Monitoring System
Authors: Braaten Nils A. , Blakset Terje J. , Morton Derek
Published: December 2007

This paper describes the use of an erosion based on-line sand monitoring system, both for topside and subsea applications. It shows the practical use of the system, both from a safety point of view, with the probe giving early warning of sand production/erosion, in addition to being a tool for optimizing the production from the oil/gas wells. The probe works equally well in all flow regimes, single or multiphase flow.
Forecasting Petroleum Drilling Outcomes for Firms of Different Sizes Operating in the Gulf of Mexico OCS Region
Authors: Declare Omowumi O. , Pulsipher Allan G.
Published: December 2007

The purpose of this paper is to forecast petroleum drilling activity and outcomes for firms of different sizes using a model of hydrocarbon reserve additions developed for the Gulf of Mexico OCS region. Our empirical results provide evidence of statistically significant diminishing returns on drilling effectiveness with the growing maturity of the OCS region, but are inconclusive, statistically, as to whether technological change boosts drilling effectiveness differently among firms of different sizes. The response of drilling to economic incentives is inelastic among the independents but nearly unitary-elastic for the majors. Overall, there is no persuasive evidence to suggest a less aggressive drilling pace or less efficient hydrocarbon resource development on the Gulf OCS because of an increasing role of independents in the region.
Asphaltene and Other Heavy-Organic Particle Deposition During Transfer and Production Operations
Authors: Escobedo Joel , Mansoori G. Ali
Published: December 2007

The production and transportation of petroleum fluids could be severely affected by deposition of suspended particles (i.e. asphaltene, paraffin/wax, sand, and/or diamondoid) in the production wells and/or transfer pipelines. In many instances the amount of precipitation is rather large causing complete plugging of these conduits. Therefore, it is important to understand the behavior of suspended particles during flow conditions.

In this paper we present an overview of the heavy organic deposition problem, its causes, effects and preventive techniques. We also present an analysis of the diffusional effects on the rate of solid particle deposition during turbulent flow conditions (crude oil production generally falls within this regime). We utilize the turbulent boundary layer theory and the concepts of mass transfer to explain the particle deposition rates on the walls of the flowing conduits. The developed model accounts for the Brownian and eddy diffusivities as well as for inertial effects and other forces acting acting upon the particles.

The analysis presented in this paper shows that rates of particle deposition (asphaltene, paraffin/wax, sand, and/or diamondoid) on the walls of the flowing channel, due solely to diffusional effects, are negligible. It is also shown that deposition rates decrease with with increasing particle size. However, when the deposition process is momentum controlled (large particles) higher deposition rates are predicted. It is shown a decrease in deposition rates with increasing crude oil kinematic viscosity. An increase in deposition rates with increasing production rates is also observed.