bluuebunny/crossref_metadata_2025_split huggingface dataset:
Underbalanced Drilling with Coiled Tubing and Well Productivity
Authors: Leising L. J. , Rike E. A. 
Published: December 2007

ABSTRACT
Horizontal wells have shown such gains in productivity in many applications that the damage associated with longtime exposure to drilling fluid was, in many cases, accepted. In addition, the dif-ficulty of removing formation damage in a horizontal well has compounded the problem. With many horizontal wells now being left in an openhole status, formation damage becomes even more important.
Coiled tubing (CT) drilling has grown from four jobs in 1991 to over 120 (estimated) jobs in 1994. The primary motivations for this growth have been: The ability of CT drilling to finish drilling a well in soft forma-tions faster than a rotary rig, andSafe, rigless underbalanced drilling to greatly reduce forma-tion damage in horizontal wells.
This paper reviews the causes of formation damage, both from fluid/solids invasion and stimulation techniques to remove dam-age.
An analytical model is used to estimate the productivity index (PI) for various horizontal and vertical permeabilities, well lengths, and reservoir thicknesses for comparison with results from several case studies.
Options for underbalanced drilling including fluid selection, gas lift, and seal technology are discussed. Candidate selection cri-teria for those evaluating the possibility of underbalanced hori-zontal drilling are presented.
Well Tractors for Highly Deviated and Horizontal Wells
Authors: Hallundbæk Jørgen 
Published: December 2007

ABSTRACT
This paper introduces the oil industry to a new type of downhole tools - the Well Tractors with modular power source designed for running in open hole and inside the completions of horizontal and highly deviated wells.
The Well Tractors are used for cleaning, setting and pulling of plugs, operating sliding sleeves, open hole logging, running of production logs, drilling, perforation guns, cement bond logs etc.
Horizontally the Well Tractors pull coiled tubing and/or wireline beyond 10,000 ft. The Well Tractors are capable of pulling more then 25,000 ft of coiled tubing and/or wireline into a highly deviated well. Furthermore the tools are designed for pushing other tools into the hole, e.g. logging tools, video cameras etc.
The Well Tractors with modular power source are designed in two versions:
A fluid driven version for coiled tubing operations. Powered by brine, water, mud etc. which is pumped down through standard coiled tubing. The tool is controlled from the surface via a wireline running inside the tubing. Through the wireline measurements can be transmitted to the surface. Alternatively the tool can also operate without the wireline which enables it to run with a smaller size of coiled tubing or have a higher flow rate for e.g. cleaning jobs.
An electric driven version of the Well Tractor for wireline operations. Powered and controlled through the wireline.
The Well Tractors are designed in 3 different sizes. A Tractor with an outside diameter of 3 1/8". A Tractor with an outside diameter of 4 3/4" and a Tractor with an outside diameter of 2 1/8".
Integrating Field Measurements With Conceptual Models to Produce a Detailed 3D Geological Model
Authors: Freulon X. C. , Dunderdale I. D. 
Published: December 2007

ABSTRACT
A three dimensional geological model of a reservoir defines the matrix heterogeneities and the petrophysical properties (porosity, permeabilities, saturations). To construct a model two sources of information are used: a conceptual model and the available measured data (subsurface and outcrop) interpolating techniques are needed. To integrate these two perspectives. In this paper two stochastic techniques are compared: the Gaussian model and the Boolean model. The integration of different types of knowledge is a crucial and innovative domain in 3D stochastic modelling and requires contact between petroleum geoscientists and engineers involved in reservoir management.
The Leman Field: Hunting for the Remaining Gas
Authors: Mijnssen F. C. J. , Maskall R. C. 
Published: December 2007

Abstract
The Leman Field is the largest discovered gas field in the southern North Sea. Production is from Rotliegend Sandstones which predominantly have an aeolian origin. In the Shell/Esso acreage the flanks of the Leman Reservoir are sparsely drilled, and potentially large amounts of gas remain in place. In these areas only the relatively poor quality uppermost part of the Rotliegend Reservoir is above the gas/water-contact. Analysing reservoir properties in the uppermost Rotliegend indicates that the variation in reservoir properties within a lithofacies is significantly larger than the variation in average reservoir properties between lithofacies. Sedimentary structures are the most likely cause for this internal heterogeneity. Consequently, drilling a well parallel to the main foreset dip, the direction of maximum heterogeneity, should maximise productivity. In the Leman Field this means that wells should be drilled parallel to the main paleowind direction, which is from southeast to northwest.
Multiphase Rotodynarnic Pumps Extend their Operating Capabilities
Authors: Falcimaigne J. , Durando P. , Loupias M. , Vilagines R. 
Published: December 2007

ABSTRACT
The paper describes the main features of the P302 multiphase pump and presents some results of bench tests carried out to check its hydraulic performances. The P302 is a rotodynamic helico- axial pump based on the Poseidon pumping technology. It is equipped with water lubricated bearings and driven by a high speed electrical motor. The pump was designed to work with a suction pressure much lower than the P300 prototype and to deliver a higher compression ratio. It has fifteen stages of compression cells, in three different series.
Before installing the pump on an onshore production site for endurance tests with actual field fluids, the steady-state behaviour and the transient responses of the pump were characterised on the IFP multiphase loop at Solaize (France). The pump was tested both with single phase fluids (liquid or gas) and a diphasic mixture (fuel-oil and nitrogen) at various GVF and suction pressures. In the paper, theoretical predictions are compared to measured data.
The good results of these tests confirmed the soundness and versatility of the Poseidon hydraulics and also the calculation model ability to predict accurately the performances of rotodynamic pump over a wide range of operating conditions.
Re-Use Rather Than Abandon Offshore Facilities
Authors: Broad T. A. 
Published: December 2007

Abstract
The technology to remove offshore facilities without dismantling them offshore is cost efficient. It also enables a platform topside to be re-used at another location for a significantly lower cost and with an earlier first oil date than that possible by building a new platform. Safety of personnel and security of the environment can be maintained throughout the removal, refurbishment and re-installation operations.
Cost-Effective Field Development Planning and Risk Assessment
Authors: Lane Ian , Early R. K. , Holtslag R. J. 
Published: December 2007

ABSTRACT
This paper will discuss the concept and application of risk management in the North Sea, a mature oil province which now presents increasingly high cost, marginal development prospects. Examples of an integrated approach to risk assessment in field development planning, involving both petroleum and well engineering disciplines, will be examined using case histories from both mature fields and new projects. The use of leading edge technologies in this process will be discussed, in the context of introducing risk and the quantification of possible upsides and downsides in the process of optimising the overall economic return of a project.
Qualification of an HP/HT Retrievable Production Packer
Authors: Fennell Bob , Avignon Bernard , Henderson W. D. 
Published: December 2007

Abstract
Well completion of future HP/HT fields are posing great financial and technological challenges to operators and service companies alike. Field proven equipment already exists to develop such fields but financial and system optimisation is now the driving force behind technological advances. This optimisation drive linked to the overriding HP/HT completion philosophy of keeping completion procedures simple and efficient indicated the requirement of a hydraulic set, retrievable production packer.
This paper looks at HP/HT completion design concepts and equipment qualification concentrating on new technologies being developed and qualified for the production packer. The process of identifying the requirement through to full scale prototype qualification is described.
Bull Heading To Kill Live Gas Wells
Authors: Oudeman Pieter , ter Avest Dick , Grodal E. O. , Asheim H. A. , Meissner R. J. H. 
Published: December 2007

ABSTRACT
To kill a live closed-in gas well by bull heading down the tubing, the selected pump rate should be high enough to ensure efficient displacement of the gas into the formation (i.e. to avoid the kill fluid bypassing the gas). On the other hand, the pressures that develop during bull heading at high rate must not exceed wellhead pressure rating, tubing or casing burst pressures or the formation breakdown gradient, since this will lead, at best, to a very inefficient kill job. Given these constraints, the optimum kill rate, required hydraulic horsepower, density and type of kill fluids have to be selected. For this purpose a numerical simulator has been developed, which predicts the sequence of events during bull heading. Pressures and flow rates in the well during the kill job are calculated, taking into account slip between the gas and kill fluid, hydrostatic and friction pressure drop, wellbore gas compression and leak-off to the formation. Comparison with the results of a dedicated field test demonstrates that these parameters can be estimated accurately. Example calculations will be presented to show how the simulator can be used to identify an optimum kill scenario.
Reliability Analysis on PVT Correlations
Authors: De Ghetto Giambattista , Paone Francesco , Villa Marco 
Published: December 2007

Abstract
This paper evaluates the reliability of the most common empirical correlations used for determining reservoir fluid properties whenever laboratory PVT data are not available: bubblepoint pressure, solution GOR, bubblepoint OF W, isothermal compressibility, dead-oil viscosity, gas-saturated oil viscosity and undersaturated oil viscosity.
The reliability of the correlations has been evaluated against a set of 195 crude oil samples collected from the Mediterranean Basin, Africa, the Persian Gulf and the North Sea. About 3700 measured data points have been collected and investigated. All measured data points are reported in the paper. For all the correlations, the following statistical parameters have been calculated: a) relative deviation between estimated and experimental values, b) average absolute percent error, c) standard deviation.
Oil samples have been divided into the following four different API gravity classes: extra-heavy oils for °API&lt; 10, heavy oils for 10&lt;°API≤ 22.3, medium oils for 22.3&lt;°API&lt; 31.1, light oils for °API&gt; 31.1.
The best correlations both for each class and for the whole range of API gravity have been evaluated for each oil-property.
The functional forms of the correlations that gave the best results for each oil property have been used for finding a better coiTelation with average errors reduced by 5-10%. In particular, for extra-heavy oils, since no correlations are available in literature (except for viscosity), a special investigation has been performed and new equations are proposed.
J-Block Template Drilling: Innovation and Teamwork Break Cost and Time Barriers
Authors: Henderson K. W. 
Published: December 2007

ABSTRACT
Phillips Petroleum Co. U.K. Ltd (Phillips) commenced template drilling on the Judy and Joanne field development in Block 30/7a (J-block) in May 1993. Since that time progress has been remarkable. Following the setting of a 65 Tonne, 12 slot, drilling template by a 4th Generation Universe Class jackup, two 70" holes were drilled for docking pile installation. The 120 ft long, 60.5'' diameter, 100 tonne piles were picked up from a vessel using the rig draw-works and run and cemented using standard oilfield equipment. It is believed that this is the first time such an operation has been carried out from a jackup drilling rig. Batch setting of 7 tapered and 2 conventional conductor strings through 9 template slots was completed inside 12 days. The optimal and unique well design then allowed drilling to proceed at record rates, including a world record of 8,263 ft of 12-1/4" hole in one 24 hr period being achieved.
This paper discusses the innovative engineering, design, cost reduction and teamwork philosophy that has seen the project progress ahead of schedule and significantly under budget.
Experience in the Detection and Suppression of Torsional Vibration From Mud Logging Data
Authors: Fear M. J. , Abbassian Fereidoun 
Published: December 2007

ABSTRACT
Vibration detection from mud logging systems has revealed that torsional vibration is common in harsh drilling environments, and is a major cause of bit and drillstring failures. Suppressing this type of vibration with an automated vibration detection system, torque feedback, and rigsite vibration suppression guidelines has produced a significant improvement in drilling performance.
Application of QRA Methods to Casing Seat Selection
Authors: Parfitt S. H. L. , Thorogood J. L. 
Published: December 2007

Abstract
There are diverse approaches to casing setting depth determination via kick tolerance, which are inconsistent with each other and involve apparently arbitrary design values. This paper presents a risk based approach to setting depth selection during design which explicity considers the variables contributing to influx volume and their uncertainties. The use of a risk based approach provides a unifying theme across a range of hole sizes and operational variables allowing comparisons of options where none was possible using previous design approaches.
Post-Frac Productivity Calculation for Complex Reservoir/Fracture Geometry
Authors: Bale Arthur , Smith M. B. , Settari Antonin 
Published: December 2007

ABSTRACT
This paper presents a simple, practical approach to calculating postfrac productivity for indirect vertical fracture completion (IVFC) wells. The case envisioned is one where the main pay is not adjacent to perforations; with wellbore-to-pay communication being created via a wide propped vertical fracture. Such a fracture generally involves tip screenout type treatment designs, though that is not a subject of this paper.
Previous publications1,2 presented a case history of limiting perforations in a well to competent, lower permeability rock, and creating a propped fracture to communicate with weaker, higher permeability pay. An IVFC well in this formation served two goals: 1) to avoid need for gravel packing or other sand control measures required when the main pay is perforated, and 2) to maximize production from lower permeability pay sections, thus delaying water breakthrough (WBT) and increasing total reserve recovery. As part of that case history, a brief calculation scheme was proposed for predicting post-frac PI.
This paper discusses details of this calculation procedure, which is presented in a more general (partly dimension- less) form. Examples of predicted PI using these calculations are presented for several field cases where complex fracture completions of this type are being considered and implemented. In addition, accuracy of the simple, analytical calculations are tested against 3-D reservoir modeling. Results of the numerical modeling generally verify the simple procedure, but also place some limits on where / when analytical calculations should be used. The 3-D model is then used to consider possible impacts of turbulent flow and other parameters not included in the analytical calculation. Turbulent flow in the fracture was found to be a significant factor, even for single phase flow of oil.
Finally, predicted PI is compared to field measured post- frac results for several cases. Many field cases show unmistakable indications of turbulent flow, making it clear this factor must be considered in design of such completions.
Geotechnical Integration and its Impact on Field Management. The IRMA Methodology.
Authors: Riddiford F. A. , Goupillot M. 
Published: December 2007

Abstract
The ability to accurately model sub-surface reservoir detail and those features which are likely to control and influence the displacement processes associated with hydrocarbon production, is essential if we are to improve our ability to predict field performance. This paper outlines a methodology for fully integrating data into a comprehensive description of the sub-surface, which can be rapidly updated as new data become available, and the processes of Upscaling and Downscaling undertaken in moving between these detailed geological models and the simulation environment. The benefits of using 3D seismic data to improve our understanding of the sub-surface, are discussed.
The process of data integration utilising an insight gained from both static as well as dynamic data is used to develop 3D numerical models of the sub-surface. Static data comprising acoustic impedance 3D blocks extracted from well and seismic, combined with petrophysical models calibrated using core and log data, constrain geostatistical models developed at the sand body scale. Object models and fault and fracture information developed from core and seismic data are also combined to give unified static geological models at the stratigraphic scale, which are consistent with all the known data. The impact of dynamic disturbance from evaluation of well test and RFT data are similarly used to constrain the plausibility of the geological models being built.
Upscaling of the detailed geological models provides data sets of a size consistent with running reservoir simulation models. Downscaling to address history match issues and reservoir monitoring including 4D seismic, ensures that reference is always made back to the current geological model, this the vehicle through which all change is invoked.
Field examples are used to demonstrate the benefits and the interactive and iterative nature of this innovative methodology, which combines existing and newly developed techniques from exploration and production to develop geological and equivalent simulation models, which are fully consistent across the sub-surface disciplines.
Historical Performance of Gas Injection of Ekofisk
Authors: Jakobsson N. M. , Christian T. M. 
Published: December 2007

Abstract
Hydrocarbon gas has been injected into the Ekofisk field for almost twenty years. Gas injection has always been for operational reasons. This case history reviews the historical performance and benefits of the gas injection. Gas migration, gas distribution and mechanisms involved when gas is injected into a naturally fractured chalk reservoir are discussed. The findings are based on field and laboratory data. The benefits are estimated by means of reservoir modelling.
The Ekofisk field is a naturally fractured chalk reservoir with low matrix permeability. The natural fracturing enhances overall permeability and has made commercial production possible. Since gas injection commenced in 1975, a total of 1.2 TSCF of gas has been injected. All the gas has been injected into the crest of the field.
This paper demonstrates that the natural fracture system at Ekofisk represents a medium for the injected gas to contact and mix with the reservoir fluids and that major fault systems are important factors for gas migration and gas distribution. There is no clear oil production response to gas injection. The production response that can be observed is generally limited to elevated GOR. Gas injection still appears to have benefitted oil recovery. Reservoir modelling suggests that gas injection will increase oil recovery by 2 to 3 percent of original oil in place. Historical benefits are, in addition to pressure support, swelling of the oil and vaporization/stripping of lighter hydrocarbons.
Surfactant Design Criteria for Successful Carbon Dioxide Foam in Sandstone Reservoirs
Authors: Kuhlman M. I. , Lau H. C. , Falls A. H. 
Published: December 2007

Abstract
Laboratory results demonstrate that surfactant adsorption on sandstones is minimized and foam performance improved by reducing the ethoxylate chain length in alcohol ethoxy sulfonates and blending unethoxylated and ethoxylated sulfonates to optimize desirable properties. These properties include increased mobility reduction, more gas-oil foam formation, and enhanced surfactant transport in the oil and water, which all appear to be negatively affected by the presence of long ethoxylate chains in a surfactant.
A series of experiments are used to show that laboratory adsorption measurements can only be extrapolated to reservoirs by 1) replicating the anaerobic conditions of reservoirs, 2) matching the reservoir pH in a CO2 flood and 3) differentiating authogenic minerals from drilling mud found in reservoir cores.
Thermal Stability of Sulfonated Polymers
Authors: Audibert A. , Argillier J-F. 
Published: December 2007

ABSTRACT
Polyacrylamides which are used in oil applications i.e. polymer flooding and water based muds, are hydrolysed versus time and temperature. This leads to a lack of tolerance towards electrolyte contamination and to a rapid degradation inducing a loss of their properties. Modifications of polyacrylamide structure have been proposed to postpone their thermal stability to higher temperatures. Monomers such as acrylamido methylpropane sulfonate (AMPS) or sulfonated styrene/maleic anhydride can be used to prevent acrylamide comonomer from hydrolysis. The aim of this work is to study under controlled conditions, i.e. anaerobic atmosphere, neutral pH, the stability of sulfonated polymers in order to distinguish between hydrolysis and radical degradation reactions.
It has been observed that up to 100°C, the AMPS group is stable and protects the acrylamide function from hydrolysis up to 80%. At higher temperature, even the hydrolysis of the AMPS group occurs, giving acrylate and β, β dimethyl taurine, with a kinetics that depends on temperature and time. Degradation in terms of molecular weight then occurs indicating that it follows a radical decarboxylation reaction. It can be limited either by the use of free radical scavenger or when the polymer is in the presence of a mineral phase such as bentonite.
These results provide valuable data for the determination of the limits of use of sulfonated copolymers and guidelines for optimizing chemical structure of sulfonated polymers used in water based formulation, in particular to enhance their thermal stability.