bluuebunny/crossref_metadata_2025 huggingface dataset:
Hole Cleaning Capabilities of Drilling Foams Compared to Conventional Fluids
Authors: Saintpere Stephane , Marcillat Yannick , Bruni Fabrice , Toure Abdoulaye
Published: December 2007

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.
History of the Ownerships of Mineral Rights
Authors: Gruy H. J. , Gruy J. J.
Published: December 2007

This is the only country in the world in which the mineral rights belong to the surface owner and not to the government or to the King. This paper presents the lawsuits and court rulings that brought this about.
Compositional Grading – Theory and Practice
Authors: Høier Lars , Whitson Curtis H.
Published: December 2007

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

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

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

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

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

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

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

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

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

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

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

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

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.
Development of a Large-Bore Monobore Completion System for Gas Production
Authors: Simonds Randy , Swan Tom
Published: December 2007

Traditionally, monobore completion techniques have been able to provide operators with a high degree of flexibility for maintenance needs since the tubing imposes no restriction to any tool that may be deployed in the liner as sometimes happens when completions have tapered production strings. Unfortunately, the traditional monobore completion advantages may not be realized until later in the life of the well. While maintenance is always important, the general volatility of oil prices has forced the industry to target operational strategies that can also offer quicker returns on investment. Since the completion system discussed in this paper employs large-diameter production tubing, it provides the maintenance benefits of a monobore system but with added advantages that a large flow area can provide. The increased flow area 1) allows the number of wells to produce a given reservoir to be reduced and 2) enables production rates to be increased, which in turn, reduces long-term operating expense since the reservoir can be depleted in a shorter period of time.

The specific benefits of the large-bore monobore completion are as follows: No restrictions are imposed on productionProduction rates are maximizedGas turbulence areas are eliminatedNo restrictions on any service/intervention toolsTubing retrieval to the liner top is allowedFull access to the liner for squeezing or mechanical isolation of the perforations is allowedAncillary equipment requirements are minimized.
Underbalanced Horizontal Drilling: A Field Study of Wellbore Stability in Brazil
Authors: Falcao José L. , Fonseca Carlos F.
Published: December 2007

This paper discusses the design and wellbore stability considerations to drill four underbalanced horizontal wells in a mature, pressure-depleted and high permeability reservoir in the onshore Estreito field-Northeast of Brazil. To do so, it was determined the minimum mud weight that produced the minimum ECD below reservoir pressure, but above the lower collapse pressure, that keeps the wellbore integrity. For that, two approaches were employed: an in-house linear elastic stability simulator, named SEST, and a poroelastic simulator that takes into account the plastic yielded area around the wellbore.

The main operational aspects related with stability of the first two horizontal underbalanced wells are also discussed. Finally, the results indicate that the methodology adopted in the design was successfully applied in the field.
Value-of-Information - from Cost-Cutting to Value-Creation
Authors: Koninx Jean-Paul M.
Published: December 2007

Value-of-Information analyses are a powerful tool for short- term rationalisation of data acquisition costs. But even more so the longer-term added value of proper VOI analyses lies in the process of constructing the analysis, and in the insight it gives into risk and opportunity management. A rigorous VOI analysis generally spans the full life cycle of E&P, and as such requires input from a multi-disciplinary team. A thorough scrutiny about where data adds value will lead to value optimisation and creation.

In order to unlock this value, implementation of a rigorous and easy-to-use methodology is critical. Such an implementation has progressed in Woodside, and has already led to a shift in mindset. VOI analyses are less regarded as cumbersome and fuzzy, but more and more as an essential part of data acquisition and data analysis. As a result, sizeable reductions in well data acquisition costs have been achieved, and data acquisition and analysis has become more focused.
Well Construction and Intervention Engineering Using a Relational Database
Authors: Thomson S. M. , Manifold C. B.
Published: December 2007

The management of information and the work-flow process associated with completions, workovers and other well- intervention activities in a large hydrocarbon-producing basin can be improved with a consistent and controlled system. Santos' Petroleum Engineering Operations group in Queensland, together with Advanced Well Technologies, have developed a FileMaker Pro™ database to streamline the work- flow processes required to manage the completions, workovers and other well-intervention activities effectively.
New Workover and Completion Technology Utilised in Bass Strait
Authors: Eaton M. L. , Barry A. G. , Schoemaker S.
Published: December 2007

As production from the Gippsland Basin in Bass Strait Australia passes the 30 year mark, the need to find innovative techniques to maximise production from this world class maturing basin is a principle priority for the operator. To address this issue, Esso Australia, on behalf of the 50:50 joint venture with BHP, recently embarked on a concentrated program to trial and evaluate several new technologies being developed by industry.

This paper discusses several technologies that were employed to increase production, enhance reservoir recovery and improve well integrity. Varying degrees of success were achieved during these trials and the successes, failures and lessons learned will be outlined.

The technologies discussed include: Scab liners with inflatable packers set through tubing in horizontal wells to isolate water/gas production;Gas and water shut off techniques utilising polymer technology;Wellhead leak sealing technology using differential pressure-set coagulating polymers;Wirelineless completions using expendable plugs and perforating gun hanger systems on space limited platforms (during infill drilling operations);Through-tubing deep penetration perforating charges used to stimulate production from wells with extensive near wellbore damage; andMini-fracturing gas stimulation technology used on poor performing reservoirs.

The high level of mechanical success combined with encouraging reservoir success in some instances is promoting a continued search for further production enhancing techniques.
Monitoring and Control of Water Influx in Strong Aquifer Drive Gas Fields Offshore Sarawak
Authors: Veeken C. A. M. , Chin H. -V. , Ross R. W. , Newell M. D.
Published: December 2007

The M3 and M1 gas fields offshore Sarawak experience exhibit aquifer support that is stronger than expected and markedly non-uniform in nature. This has resulted in rapid water breakthrough in 4 out of 7 development gas wells in M3. This paper describes the surveillance and remedial activities that were implemented to respectively monitor the aquifer rise and the associated water production and to reduce the detrimental impact of water breakthrough on gas well capacity.
Critical Wellbore Considerations for Successful Carbon-Oxygen Log Applications: Benefits of a Teamwork Approach
Authors: Tran Thanh Binh , Fox Phil , Adnyana I. Gede , Nguyen Chuong
Published: December 2007

For many of Asia Pacific low salinity medium to high porosity oil reservoirs, carbon-oxygen (C/O) logging has provided an effective method of through casing reservoir surveillance. This technology has been applied for well over two decades to provide saturation characterizations in conditions that are often challenging even in the openhole environment. To be successful, however, close attention must be paid to strict criteria during stages of problem identification, candidate review, well preparation, data acquisition, data processing and tool response interpretation.

A joint team was formed last year between operating company and service provider personnel. The charter of this group was to form standing best practices designed to optimize results from this technology. Case examples1 of interest related to this effort included: comparison of calcium yields to the open-hole caliper in a washed-out boreholeC/O responses in an apparent extensive exterior borehole cavern that potentially was a result of formation sandingtime-lapse, post cement-squeeze, near-wellbore fluid displacement recovery observed with monitor logging runspotential misinterpretation from log responses through an oil-filled cement sheath channelinter-reservoir cross-flow flushing induced saturation distortion resulting in failure to evaluate true reservoir hydrocarbon volumetricsestimation of reservoir saturation from within a hydrocarbon-rich boreholeeffects of formation lithology on C/O log responsesusing C/O to locate bypassed reserves in coning reservoirsusing C/O to monitor water and steam flood fields as an input to reservoir description modelingeconomic gains realized from recent C/O log applications

This paper presents a short C/O technology overview, historical review of past practices, a review of joint discussions between team members providing and using the associated log application techniques and describes the ongoing Carbon-Oxygen Workshop Forum (COWF) review series. Additionally, some key C/O best practices developed from over 150 logging experiences in Indonesia are highlighted.
Design and Execution of a 3000-ft Horizontal Gravel-Packed Completion (A Kazakhstan Case History)
Authors: Tibbles Raymond , Blessen Elton , Qian Xiang , Steven Bill , Pardo Carlos , Hurst Gary , Kubota Randall , Mysko Peter
Published: December 2007

This paper discusses the planning, design and successful execution of the first horizontal gravel pack in Texaco's remote North Buzachi field. Well NB4Z, located on land in Kazakhstan, presented extreme challenges that greatly affected the planning of the completion process.

Example of the challenges include the following: The combination of a 3000-ft-long openhole lateral section in a shallow reservoir meant that the screen would be over 1000 ft into the openhole before the gravel-pack packer was connected on the rig floor.The location had a limited supply of water for completion operations. Disposal of water was also a problem.The shallow reservoir made the screen placement problematic and made the torque and drag calculation much more critical.Because of the limited number of evaluation wells, everything had to work correctly the first time; i.e., there were no learning curve opportunities.

All aspects of the gravel-pack design are discussed (drilling fluid selection, torque and drag calculations, screen selection, selection of gravel-pack method, and pumping design). The successful executions of various completion phases are compared with the initial designs, and postcompletion well production is discussed.

This horizontal completion set several records. Among them are records for the longest slurry pack, the longest horizontal well to be gravel packed without washpipe and the longest gravel pack using shunt screen technology. The design took an existing technology, enhanced it and stretched its application to a new limit, in the process obtaining a successful result.
Emerging Techniques in Gravel Packing Open-Hole Horizontal Completions in High-Performance Wells
Authors: Parlar M. , Bennett C. , Gilchrist J. , Elliott F. , Troncoso J. , Price-Smith C. , Brady M. , Tibbles R. J. , Kelkar S. , Hoxha B. , Foxenberg W. E.
Published: December 2007

Gravel-packing of open-hole highly-deviated or horizontal wells is increasingly becoming a common practice, especially in deep water and sub-sea completion environments where production rates may reach up to 50,000 BOPD or 250 MMSCFD. In these wells, reliability of the sand face completion, in addition to other factors, is of utmost importance due to the prohibitively high cost of intervention or side-tracking and the very high hydrocarbon recoveries required per well. To date the norm in gravel-packing such wells is water-packing or shunt-packing with water-based fluids. With both techniques, filter-cake removal treatments are conventionally done through coiled tubing after gravel packing, pulling out of the hole with the service tool and running in with the production/injection tubing. Furthermore, because conventional gravel-pack carrier fluids are water-based (brine or viscous fluids), water-based drilling fluids are traditionally used to drill the reservoir section to ensure compatibility and improve wellbore cleanup, even if the upper hole is drilled with a synthetic/oil-based drilling fluid.

In this paper, we discuss several novel techniques that can substantially improve return on investment in gravel packing of open-hole horizontal completions, through reduced cost and process time, improved fluid management practices, increased productivity and/or reduced risk of future interventions, so mitigating against the risk of sand face completion failure or under-performance. The proposed techniques include: Simultaneous gravel-packing and filter-cake removal with water-based carrier fluids when the reservoir is drilled with a water-based drilling fluid: laboratory data relevant to gravel-packing are given and field case histories are discussed in detail.Simultaneous gravel-packing and cake cleanup with either water or a synthetic/oil-based carrier fluid when the reservoir is drilled with a synthetic/oil-based drilling fluid: laboratory data on cake removal while gravel packing are presented for both water-based and oil-based carrier fluids along with data on kinetics of cake removal.a new service tool that utilizes wash-pipe as continuous tubing and thus allows spotting of breaker treatments immediately after gravel packing: detailed description of the tool and its operation is given.Gravel-packing of highly-deviated or horizontal wells above fracturing pressure.

Benefits offered by each of the proposed techniques are discussed in detail along with their current limitations.
The Mutable Distributed Team: A New Business Risk in the Information Age
Authors: Goldthorpe W. H.
Published: December 2007

The power of Internet-based technologies has created work environments that are shaping a new type of team structure - the mutable distributed team. To take full advantage of the new information systems and to manage changed team dynam- ics, the problems and risks faced by such teams and their lead- ers need to be understood and new skills need to be learnt. This paper analyzes and provides examples of the class of business risks that arise from the management of mutable dis- tributed teams in the so-called Information Age.
An Innovative Approach for PSC and GSA Discussions/Negotiations
Authors: Seong Chen Kah , Kario Mohamed Wahid
Published: December 2007

PETRONAS undertook a group-wide re-engineering exercise in 1996. Following that, PETRONAS Exploration & Production Sector and PETRONAS Carigali (upstream operating arm of PETRONAS) were merged under a single E&P Business Unit. PETRONAS Exploration & Production Sector was renamed as Petroleum Management Unit (PMU) and was given the role as the custodian of PETRONAS' ownership of the nation petroleum resources. The re- engineering exercise, with PMU's key tasks well defined, has reduced the manpower of PMU by more than 50%. As such, new model had to be formulated for Production Sharing Contract (PSC) and upstream Gas Sales Agreement (GSA) negotiations with Contractors.

Discussions and negotiations on a commercial arrangement for the development of gas fields for supply to a gas utilisation project in Peninsular Malaysia (PGU Project) commenced in May 1996. Following parties agreement on the main principles of gas development and supply, PETRONAS signed the Main Terms of EPMI/Carigali Gas PSC (GPSC) with EPMI and CARIGALI in June 1997. The Main Terms of GPSC form the basis for formulating the PSC and GSA, which was signed in November 1998. The scope of the contract includes the exploration, development and production of natural gas resources from 22 fields for supply to PGU Project. The total fields development cost is estimated at USD 4.2 billion nominal dollar.

This paper will discuss on the following; brief review of the re-engineering exercise and PMU's key tasks after the re- engineering exercise, the model adopted by PETRONAS towards the PSC and GSA negotiations and will attempt to explain how is this different from the previous negotiations.
Inhibition of Lead and Zinc Sulphide Scale Deposits Formed during Production from High Temperature Oil and Condensate Reservoirs.
Authors: Jordan M. M. , Sjursaether K. , Edgerton M. C. , Bruce R.
Published: December 2007

Carbonate and sulphate scales are the most common types of mineral deposit associated with the recovery and processing of hydrocarbon and associated produced water. In three high temperature fields (>140C) within the North Sea more usual scale types have been observed namely zinc and lead sulphide. Conventional inhibitors cannot control these scale types and their removal by chemical means can result in the generation of toxic gas (H2S). The conditions for the formation of these unusual scale types is described and well as the economic impact these deposit had on hydrocarbon production of these fields. In this paper the development of a novel scale inhibitor package and its successful application in these fields is described.

Field evaluation of the inhibitor types used to control sulphide scale is described in this paper as well as the details on how the field trials were planned, carried out and evaluated. Mechanical and chemical removal are also discussed as an alternative to inhibition.

The finding of this paper significantly increase the industries understanding of sulphide scale deposits in terms of mode of formation and mechanism of inhibition. The paper stresses the critical factors to be evaluated within produced water at the early stage of field appraisal/development that can aid in the assessment of the risk of sulphide scale deposition. The development of a novel zinc and lead sulphide inhibitor gives a cost effective, environment friendly alternative to chemical or mechanical removal of such deposits.
Polymer Gel Squeeze for Gas Shutoff, Water Shutoff and Injection Profile Improvement in Bombay High Pilot Wells
Authors: Jain Prabuddha , Sharma Vinod , Raju A. V. , Patra S. K.
Published: December 2007

In heterogeneous stratified reservoirs with low vertical communication between the layers, the best results are normally achieved if the separate layers are produced with a separate set of Wells. However, in a commingled production with poor vertical sweep due to high permeable thief zones, an improved behavior of such a reservoir can be efficiently attained by controlling the injection and production rates of wells to reduce (or stop) injection in the thief zones, and/or production from high permeable layers with high water cut. Technically this can be done by recompletion of wells or with the application of gel technology.

The problem high GOR & high water cut wells of Bombay High L-III reservoir can be classified into three categories: Wells producing high amount of gas &/or water due to hardware leak and flow behind casing. The unwanted gas/water production here is due to contribution from zones not opened/exposed for production.Wells producing from multiple layers and a single layer producing major amount of gas or water. The unwanted water production may be due to breakthrough of injection water in one or more high permeable layers. The unwanted gas production may be due to cusping.Wells where early breakthrough has occurred due to thin high permeability streaks in a sublayer between Injectors and Producers. Here, the treatment may involve treating a portion of sublayer.

In the past several Chemical water shutoff jobs in Bombay High Field have resulted in failures. The job failure can mainly be attributed to high reservoir temperature and incompatibility of Gel system with reservoir rock. Gel systems were quite sensitive to variations in temperature and pH. Also cross flow in the well bore during shut in conditions was also an important reason in some cases.

An improved polymer gel treatment has been successfully applied in Bombay High Field - a high temperature carbonate reservoir, to control excessive gas or water production and to modify the injection profiles. Ten Wells were treated as a pilot: 6 for Gas Control, 3 for Water Control and 1 for Injection Profile Improvement. All the planned wells exhibited at least one, usually more than one, of the following conditions: At least one interval with vuggy porosity, poor primary cement over at least a portion of pay, additional loss of rock volume due to acidization, reservoir pressure less than hydrostatic in producing wells, differential pressure between zones due to differential depletion or water flood support.

This paper discusses in detail the lessons learnt from the job failures and the successes with the use of polymer gels in such harsh conditions of Bombay high field.
A Risk and Economic Evaluation Tool for Management of Operating Costs
Authors: Harvey Helen E. , Gration Dale P. , Martin Stephen
Published: December 2007

Management of operating costs and resource planning is fundamental to maximising asset value. However, there is a balance between the capture of cost reduction and revenue enhancement opportunities and management of health, safety, environment and integrity risks.

A process is described that allows risk reduction activities to be ranked on an equitable basis with straightforward economic opportunities. The resulting ranked list of ideas forms the basis of prioritisation for input to activity planning, estimates of budget targets to maintain asset integrity and to manage expenditure within budget targets and known levels of risk.
Effective Evaluation and Development of Diabase & Contactite Fractured Reservoir in Luo 151 Area
Authors: Yuan Xiangchun , Xing Zhengyan , Liu Xiantai , Wu Wei , Zhao KaiLian , Guo Sun , Jia Junshan
Published: December 2007

The diabase & contactite reservoir in Luo 151 Area is located in the northern wing of the Luojia nosing structure zone of Zhanhua sag. Multistage invasion formed diabase and contactite. Only poreous Hornfels and fracturted diabase are effective reservoir rock, the reservoir is characterized by strong heterogeneity with complex pore structure, fracture feature and oil-water distribution.

Applying log-constrained seismic inversion technique, and based on 3D seismic, core analyses, drilling, logging, in especial FMI logging and CMR logging, production data, the pre-production evaluation of the fractured reservoir was performed. The emphasis of reserch were put on the detailed correlation of formation, the lithofasics of diabase and Contactite, the petrophisical, especially the spatial distribution and quantitative description of poreous hornfels and fractured diabase reservoir, and the predication of the potential reservoirs. Then, the proved reserves were estimated. Based on the results, four development wells were designed and drilled in favorable oil-bearing area and the expected production were obtained.

This paper discusses the evaluation methods and results of the fractured reservoir in Luo 151 area.