bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hole Cleaning Capabilities of Drilling Foams Compared to Conventional Fluids
Authors: Saintpere Stephane , Marcillat Yannick , Bruni Fabrice , Toure Abdoulaye 
Published: December 2007

Abstract
This paper provides a comprehensive analysis of hole cleaning with drilling foam and conventional drilling fluids in inclined wells using a fluid mechanics approach without inertial effect. A simple experimental set-up was designed to study hole cleaning properties of various drilling fluids. Foams with controlled quality were generated and accurately characterized from a rheometrical point of view. These foams behave like shear thinning yield stress fluids and can be described by a Herschel-Bulkley law.
Since rheological parameters depend on foam quality, a master rheological curve was obtained by using a volume equalization procedure and the specific volume expansion ratio e (ratio of the specific volume of the foam to the specific volume of the liquid). Foams and conventional drilling fluids with various rheological characteristics were compared and their behavior regarding hole cleaning was highlighted. The effect of dimensionless parameters such as the Herschel-Bulkley number Hb (ratio of the yield stress to the viscous stress), the specific volume expansion ratio ɛ and the flow characteristic time T* (ratio of the flow time to the residence time of a fluid particle) were investigated. The influence of hole angle, particles size and concentrations were also evaluated.
On the one hand, for shear thinning yield stress fluids with the same yield stress and the same flow characteristic time, the higher the Herschel Buckley number, the better the efficiency of cuttings removal in laminar flow. Similarly, increasing the flow characteristic time T* enables better hole cleaning.
On the other hand, for higher Hb, foam hole cleaning ability is improved at high inclination and is better than with conventional drilling fluids. At these inclinations, "particles dead zones" are observed and can explain the poor hole cleaning when using conventional drilling fluids. Efficient hole cleaning with foam was found to be strongly dependent on the specific volume expansion ratio ɛ.
Specific inclinations at which the worst hole cleaning is obtained (i.e. 40° to 60°) appears to be a function of particle size and particle concentration initially present in the hole. In conclusion, Hb and characteristic time are good indicators of cuttings removal ability. Extrapolating those numbers to an ERD well would eventually provide an evaluation of the minimum circulating time necessary to remove cuttings.
Compositional Grading – Theory and Practice
Authors: Høier Lars , Whitson Curtis H. 
Published: December 2007

Abstract
This paper quantifies the potential variation in composition and PVT properties with depth due to gravity, chemical, and thermal forces. A wide range of reservoir fluid systems have been studied using all of the known published models for thermal diffusion in the non-isothermal mass transport problem.
Previous studies dealing with the combined effect of gravity and vertical thermal gradients on compositional grading have either been (1) of a theoretical nature, without examples from reservoir fluid systems, or (2) proposing one particular thermal diffusion model, usually for a specific reservoir, without comparing the results with other thermal diffusion models.
We give a short review of gravity/non-isothermal models published to date. In particular, we show quantitative differences in the various models for a wide range of reservoir fluids systems. Solution algorithms and numerical stability problems are discussed for the non-isothermal models which require numerical discretization, unlike the exact analytical solution of the isothermal gradient problem.
A discussion is given of the problems related to fluid initialization in reservoir models of complex fluid systems. This involves the synthesis of measured sample data and theoretical models. Specific recommendations are given for interpolation and extrapolation of vertical compositional gradients. The importance of dewpoint on the estimation of a gas-oil contact is emphasized, particularly for newly-discovered reservoirs where only a gas sample is available and the reservoir is near saturated.
Finally, we present two field case histories – one where the isothermal gravity/chemical equilibrium model describes measured compositional gradients in a reservoir grading continuously from a rich gas condensate to a volatile oil; and another example where the isothermal model is grossly inconsistent with measured data, and convection has apparently resulted in a more-or-less constant composition over a vertical column of nearly 5000 ft.
High Performance Emulsifiers for Synthetic Based Muds
Authors: Evans Nigel , Langlois Bruno , Audibert-Hayet Annie , Dalmazzone Christine , Deballe Eric 
Published: December 2007

Abstract
Until now, the selection of appropriate emulsifiers for non-polluting mud formulations has been largely empirical. This is mainly due to the lack of methods that sufficiently characterise the thermal stability of concentrated water-in-oil emulsions and, by extension, complete Synthetic Based Mud (SBM) formulations.
There is an increasing need in the industry to improve emulsifier performance, not only in application but also from the environmental point of view. The chemical manufacturers have responded to these challenges by the development of new chemistry and processes based on renewable natural resources that give high purity products with excellent HPHT performance and improved environmental results.
Based on techniques of Differential Scanning Calorimetry (DSC), a novel methodology has been developed to enable the characterisation of water-in-oil emulsions. This non-perturbing method permits the in-depth study of complete mud formulations. The results obtained correlate well with those observed in standardised rheological and filtration tests.
The performance of the new range of products determined by standard methods (API 13B: rheology, filtration, ageing) has been shown to be superior to conventional emulsifying systems. The application of the new methodology has advanced the level of understanding of the role of the emulsifier in SBM formulations.
Frac-Packing High-Permeability Sands in the Mahogany Field, Offshore Trinidad
Authors: Britt L. K. , Smith M. B. , Cunningham L. E. , Waters F. , Dannish G. A. , Lachance D. , Mackow H. M. 
Published: December 2007

Abstract
Historically, hydraulic fracturing has been principally applied to low permeability formations as a means of stimulating a well’s production performance. In recent years, hydraulic fracturing for formation control as well as enhanced productivity in high permeability unconsolidated formations (i.e., frac-packing) has gained broader acceptance. This paper reviews frac-pack results in the Mahogany Field, a large gas-condensate field producing from unconsolidated high permeability sands. Even though frac-packing was very successful in these applications, numerous other completion techniques such as high rate water packs and conventional gravel packing are available and still being utilized throughout the world. For a field development engineer, few guidelines are available which aid in optimizing completion decisions.
Field examples from Mahogany Field in offshore Trinidad are used to demonstrate a successful completion design selection procedure. The benefits and risks of gravel packs, high rate water packs, and frac-packing in the completion of high deliverability wells in these unconsolidated formations will be reviewed. Results of rock mechanics, fines migration, and embedment testing will be presented and coupled with a production optimization study to develop completion guidelines applied in Mahogany Field. Finally, this paper will show a direct comparison of a gravel pack completion (80 mmcfpd) and a frac-pack completion (160 mmcfpd) in offset wells from the same productive horizon. Current production performance and long term recovery predictions will be reviewed.
This paper will make the following technical contributions:
Present the results of an extensive laboratory study of rock mechanics, fines migration, and embedment testing, and show the value of such testing in making completion decisions.
Develop and present guidelines for determining the optimal completion practices in high permeability unconsolidated formations.
Show a direct comparison between a conventional cased-hole gravel pack completion and a frac-pack completion.
Present details of a successful frac-pack completion in a formation with severe fines production problems.
Application of a Completion Equipment Reliability Database in Decision Making
Authors: Molnes Einar , Strand Geir-Ove 
Published: December 2007

Abstract
A study (JIP) on reliability of well completion equipment ("Wellmaster Phase III") was completed by SINTEF in November 1999. This has resulted in a comprehensive database on well completion equipment, with a total of 8000 well-years of completion experience represented and more than 1000 downhole failures included, given as input from the 16 funding oil companies of this JIP. The database represents all categories of downhole equipment, from tubing hanger level down. The paper points towards the major contributors to well interventions and downtime, indicating industry average and benchmark failure rates of the most vital completion components. A historical evolution in reliability of Subsurface safety valves (SCSSV) is demonstrated, and the industry wide effect of reliability improvements is shown through specific examples. In the North Sea, reliability data has gained widespread acceptance for use in decision making. The paper lists several cases where reliability data of downhole equipment has been used with a major impact on field development and subsequent operational expenditures.
A Hybrid Multilateral System Provides Mechanical and Hydraulic Isolation Without Cement
Authors: Oberkircher Jim 
Published: December 2007

Abstract
In the last two years, there has been a dramatic increase in the availability and complexity of multilateral systems. Many systems with new features and improved functionality have been introduced which have enhanced the application of multilateral technology. This system is among the latest of these offerings. This innovative system is a hybrid, TAML Level 5, that provides mechanical and hydraulic isolation at the created multilateral junction without cement, and re-entry capabilities into both the main and lateral well bores. This system also is very mechanically simple to run, utilizing a minimal number of trips to establish the junction and achieve mechanical and hydraulic isolation. Primarily designed for heavy oil applications where sand control is an issue, the system has potentially far reaching applications in this and other markets.
The paper will describe the mechanical and operational functionality of the system and its’ potential applications. Results of bench and field tests will also be documented and analyzed.
The Role Of Microearthquake Monitoring In Hydrocarbon Reservoir Management
Authors: Jupe A. , Jones R. , Wilson S. , Cowles J. 
Published: December 2007

Abstract
The monitoring of induced microseismic (microearthquake) activity can provide continuous 3D time-lapse information on the hydro-geomechanical processes that take place during hydrocarbon production. This is illustrated with examples from hydrocarbon reservoirs (e.g. Ekofisk and Valhall) and also geothermal reservoirs where the technique is well established.
The current status of microseismic technology is reviewed and the implications of emerging borehole technology are discussed.
Hydrocarbon production induces pressure changes within the reservoir causing perturbations to the in situ stress conditions that re-activate small-scale reservoir faults and fractures. This re-activation manifests itself as small earthquakes, referred to as microearthquakes or microseismic activity. Microseismic monitoring can allow the spatial distribution of these processes to be mapped and quantified at distances up to 1km from a monitoring well.
This paper illustrates the enormous potential of microseismics to; Identify fault structures acting as flow channels or flow barriersImage flow anisotropy in fracture dominated reservoirsMonitor fluid pressure front movement during waterfloodAssist in targeting production/injection wellsIdentify areas of reservoir compaction and potential wellbore instabilityProvide high resolution time-lapse images of seismic velocity and anisotropyProvide information for the conditioning of reservoir simulators
Despite the demonstrated value of the technique there have been technical and cultural barriers preventing its widespread uptake. However 4D seismic has succeeded in focussing interest on the interwell region where data is sparse and to understanding more about long term reservoir behaviour. Microseismic monitoring can fill in part of this interwell knowledge gap and help our understanding of the hydro-geomechanical processes taking place within the reservoir during production.
A lack of suitable sensor installations forms the only barrier to the technical success of the microseismic monitoring technique. This barrier is disappearing rapidly with the emergence of intelligent well technology and reliable permanent borehole sensors.
Produced and Process Water Recycling Using Two Highly Efficient Systems to Make Distilled Water
Authors: Becker R. F.(Bob) 
Published: December 2007

Abstract
This paper will describe wastewater distillation using two proprietary new designed systems (PNDS) that recover over 95% of the energy required to distill water. One design uses a new mechanical vapor recompression (MVR) system to recycle produced or process water into distilled water. A second design uses waste steam to accomplish the same thing. The unique features of PNDS have overcome the past problems of MVR (1) heat exchanger scaling, and (2) fouling, without chemical additions. These features are: A unique convection heat transfer circuit.Different criteria with respect to mass flow vapor ratios.Establishment of set points to maintain the desired "wetted effect".Managing the desired concentration effect (C.E.) over long periods of operations.
Commercial scale applications, document that more than 95% of the operating cost of distillation is energy. Thus the PNDS reduce the total operating cost by 90%.
Integrating Core Measurements and NMR Logs in Complex Lithology
Authors: Agut R. , Levallois B. , Klopf W. 
Published: December 2007

Abstract
Standard analysis of NMR logs, based on the use of a unique T2 cut-off to discriminate free and bound fluid and estimate irreducible water saturation and permeability, gives erroneous results in complex lithologies. In the example of a mixed platform presented, the main difficulty came from the strong variations between clastics, dolomite and limestones due to the heterogeneity of the porous network.
In the proposed method, illustrated by a field case, a single T2 cut-off (derived from lab NMR) for both sandstone and dolomite was found and gave good results whereas a more detailed porous network description was necessary to handle limestones. A complete set of lab measurements was used to characterize the porous network and classify carbonates following their relaxation behavior: Mercury injection capillary pressure measurements gave a pore throat distribution that was compared to 100% water saturated state NMR which is related to pore size;Microscopic images and thin section analysis allowed to illustrate the various limestone pore systems and helped to classify them by using a pseudo-quantitative pore size estimation from image processing.
The results obtained with this method based on core data integration are presented and validated by irreducible water saturation from centrifugation and conventional permeability measurements.
Full understanding of the porous system based on extensive core analysis is necessary to link the continuous log response and the dynamic parameters of the reservoir. Small changes in mineralogy affect significantly production performance.
Mobility of Foam in Heterogeneous Media: Flow Parallel and Perpendicular to Stratification
Authors: Tanzil Dicksen , Hirasaki George J. , Miller Clarence A. 
Published: December 2007

Abstract
Experiments in homogeneous and heterogeneous sand-packed columns showed that the foam mobility in the two cases could differ by two orders of magnitude. The difference is due to the generation of foam lamellae by snap-off for flow across an abrupt increase in permeability. This mechanism is shown to be dependent on the degree of permeability contrast and the gas fractional flow. It has important implications for the degree of gravity segregation of gas and liquid in field scale recovery processes.
Hydraulic Fracturing Stimulation in Poorly Consolidated Sand: Mechanisms and Consequences
Authors: Khodaverdian Mohamad , McElfresh Paul 
Published: December 2007

Abstract
A series of hydraulic fracturing injection experiments was performed in unconsolidated sand in a radial flow cell (RFC) to delineate the fundamental mechanisms controlling fracture propagation. The results of this work will be used to optimize the current fracpacking practices in unconsolidated and poorly consolidated sand and to develop adequate modeling techniques. Although the generic word "fracture" is used throughout this document and elsewhere to describe injection-induced formation parting during stimulation, it will be made clear that the tip propagation mechanisms in unconsolidated sand are fundamentally different from linear elastic fracture mechanics (LEFM) as defined for competent rocks.
Conceptually, the RFC used for the injection tests simulates a 1 -ft thick section of unconsolidated sand formation within a 3-ft radius of a wellbore. The tests in this system included injection of cross-linked guar and visco-elastic surfactant into 3,000 md sand samples subjected to different overburden stresses. The following is a summary of the findings: The experimental data suggest that "fracture" propagation in unconsolidated sand is primarily a result of shear failure in a process-zone ahead of the fracture tip. The shear failure is caused by large tip stresses (due to tip plasticity) and by pore pressure increase within the process zone.Uncharacteristically large net fracturing pressures (NFP) were encountered for low-efficiency fluids. Generally, the NFP increased with decreasing fluid efficiency.Multiple sub-parallel fracturing and complex fracture geometry was encountered. Sub-parallel fractures may be initiated at the tip or at the fracture wall due to shear failure and is dependent on the fluid efficiency and the type of leakoff, i.e., wall building or viscous. The field consequences of sub-parallel fracturing during stimulation may include premature screenout and fracture bridging, short fracture length and extensive formation damage as the fracturing fluid invades the sheared interfaces.
Point-the-Bit Rotary Steerable System: Theory and Field Results
Authors: Schaaf Stuart , Mallary C. R. , Pafitis Demos 
Published: December 2007

Abstract
Many existing rotary steerable systems rely on non-rotating, stationary pads or stabilizers to provide changes in borehole direction. An inherent weakness with this technique is that it relies on contact with the borehole wall to achieve predictable and consistent directional control. Hole washouts and borehole rugosity can negatively impact the directional performance of these systems.
A new rotary steerable system has been developed that does not depend on wall contact by non-moving parts. This new technology uses what is being termed a "point-the-bit" technique to enable precise, consistent and predictable changes in well trajectory.
This paper presents the design objectives and theory behind the "point-the-bit" system and contrasts it with existing rotary steerable systems. A case history from a successful field trial completed in Alaska is provided and includes well objectives and operational results.
Multilateral Technology, State-of-the-Art Downhole Milling Equipment, and Underbalanced Perforating Techniques Combine to Meet Challenges to Maximize Last Slot on Subsea Template
Authors: Andel Dirk Alexander , Tawse Patrick Ian 
Published: December 2007

Abstract
Shell UK Exploration & Production, operating in the UK sector of the North Sea for Shell and Esso, wished to develop a subsea oil producer that would intersect three sub-blocks and would require drilling and completion from a semi submersible rig. Since only one slot remained in the manifold, a multilateral concept was chosen for the completion. The installation would be a level 4 multilateral, based on analytical data that showed that the junction exit rock had sufficient formation strength to permit the planned underbalance perforation and contain overpressure load cases. (Difficult conditions to address in the development and completion scenario would be contingency planning for two levels of event and the capability to recover the main bore should any unforeseen nonconformance occur during completion operations) not clear.
Bad weather became a significant issue when various delays in the rig schedule set back operations from a planned September to December start date. While junction depth at around 10,000 ft and 30° was not considered too difficult to manage, depth correlation was considered critical. The well environment was unusual in that several zones were intersected in the reservoir with a varying range of pressures.
One of the key factors contributing to the success of the project was a new generation of downhole motion compensator equipment that was being tested for the first time in inclement weather conditions. Use of this equipment enabled milling work to continue in seas causing rig heave of up to 13 ft., and the downhole milling work was successfully performed in spite of the severe midwinter weather conditions that prevailed.
The well was successfully and safely completed and perforated, and all the well objectives were met. The lessons learned from the project are applicable to future multilateral operations whether deployment is from a fixed installation or a semi-submersible. Never happened.
Well Data Acquisition Strategies
Authors: Louis A. , Boehm C. , Sancho J. , Carlin S. , Cerri R. , Maglione R. 
Published: December 2007

Abstract
Preparing acquisition programmes for Exploration and Appraisal wells requires a subsurface vision of the problems to be tackled, analysis of the needs for the potential Development, and consideration of technical and budget constraints.
Determined to achieve better, faster appraisal, ELF EP and ENI Agip Division began by calling into question their vision of well data acquisition. Well data are particularly crucial in the Exploration and Appraisal phases, because investment decisions have to be taken while the information available is fragile and incomplete, whence the necessity of maximising the relevance of this information.
In a joint project the two companies therefore set about developing the ties between data needs, their applications, return, and well architecture. The resulting deliverable is a set of utilities and decisional aids which facilitate optimum preparation of integrated well acquisition programmes. With their help, all the uncertainties can be explicitly specified in the well prognosis as elementary parameters. Each parameter is then matched with the most appropriate acquisition techniques and the corresponding well design specifications. In this way, the justifications, alternatives and potential return of each measurement are transmitted to the drilling site, where the acquisition is executed.
This method helps concentrate data gathering on the first wells, to provide maximum input for early development studies, to be conducted concurrently with the appraisal work. Moreover, the emphasis put on the early data on each well contributes to increased reactivity and cost effectiveness.