bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimising Brown Field Redevelopment Options Using A Decision Risk Assessment: Case Study—Bokor Field, Malaysia
Authors: Wongnapapisan B. , Flew S. , Boyd F. , Hassan Z.
Published: December 2007

The proposed revitalization of the Bokor field is affected by many surface-facility constraints as well as the subsurface complexity of laminated stacked reservoirs. Such complex problems require a truly integrated multidisciplinary methodology using a decision-and-risk- assessment approach to screen development options. This paper presents the process adopted and used to screen and rank the various options.

Any field redevelopment needs to begin with an identification of system bottlenecks and proposals to remove them, but often this is only considered at a facilities level. In proposing a revitalization plan for the Bokor field, the joint Petronas Carigali Sdn. Bhd (PCSB)-Schlumberger team had to develop a complex decision-making process to select an optimal development plan that would solve the constraints while minimizing unit technical operating cost (UTOC) and maximizing production.

Often, brownfield redevelopments are limited to maximizing existing facilities (slots, processing plant). However, in the case of Bokor, essentially no additional oil can be produced without an impact on existing production (lack of gas lift, lack of export compression). Thus, an approach was required that not only solved the existing bottlenecks but also allowed for sufficient additional capacity to sustain a cost-effective revitalization plan. The process had to be iterative, assessing the risks and uncertainties of each approach and its economic impact.

The solution was an approach that considered each reservoir target by discounted cumulative oil, thus producing a ranked list of opportunities that could be added together to form any development scenario. Hence, rather than running a reservoir simulation on each development case, this approach allowed multiple facility development options to be tried quickly. Each development scenario was then analysed using a tornado diagram. From this diagram was prepared a decision tree that gave the most likely outcome. This approach allowed options as diverse as subsea tiebacks to full integrated platforms with a high number of electrical submersible pumps (ESPs) to be risked and ranked equitably within a reasonable timeframe.
In-situ Stress and Pore Pressure Fields in the North Cuu Long Basin, Offshore Vietnam
Authors: Thi Thanh Nguyen Binh , Tokunaga Tomochika , Okui Akihiko
Published: December 2007

Knowledge of the in-situ stress field is vital for planning optimum orientations of inclined and horizontal wells, for reservoir characterization, as well as for a better understanding of geodynamic processes and their effects on basin evolution.

In this study, we analyzed in-situ stress and pore pressure fields of Pre-Cenozoic basement and cover strata in the northern part of the Cuu Long Basin, offshore Vietnam, for the first time, based on available data from petroleum exploration and exploitation wells.

The directions of minimum and maximum horizontal stresses were evaluated from borehole breakout and drilling-induced tensile fracture orientations. The maximum horizontal stress is oriented approximately NNW-SSE to N-S, and the minimum horizontal stress is ENE-WSW to E-W orientation.

The magnitude of overburden stress was determined from density logs. Minimum horizontal stress was analyzed from good quality extended leak-off tests and mini-falloff tests. Maximum horizontal stress was estimated using breakdown equation of hydraulic fracture.

Pore pressure was measured by RFT and DST. Overpressured condition was found in the upper Oligocene, while other units showed nearly hydrostatic condition except for the depleted intervals due to production.

The effect of pore pressure change on in-situ stress magnitude was established based on the data from depleted pore pressure zone. From the obtained results from this analysis, we can reasonably well delineate in-situ stress and pore pressure fields of the area.
New Analytical Correction for Multi-Phase Flow Effect in Near-Well Regions of Coarse-Grid System
Authors: Nakashima T. , Nomura M.
Published: December 2007

In a finite difference scheme, continuous multi-phase flow variables that appear in conservation equations such as saturation are spacially discretized on grid blocks. When coarse grid blocks are used for reservoir simulation, the numerical solution tends to magnify the discretization error. This causes numerical errors called as coarse grid effect.

Through a coarse grid reservoir simulation, injection pressure showed quite difference with that of fine grid model.

This is because total mobility at the injection well is defined by the finite difference based average saturation in the injection well grid block. In other words, the saturation gradient that would appear in the near-well region is ignored in such coarse-grid system.

In this study, the areal average saturation in the injection well grid block was calculated analytically by the newly derived radial displacement approximation which was extende from the Buckley-Leverett linear displacement problem, taking account of pressure difference between the injection well and the injection well grid block. Consequently, the corrected total mobility was provided, by defining new value of total well index and transmissibility.

The injection pressure computed by this technique with for coarse grid model is reasonably agreed with the numerical solution of fine grid model. The practical application of the developed well-pseudo is validated through an actual reservoir simulation study.
Rights Of Access And Permitting For Coalbed Methane Operations
Authors: Lear J.D. Phillip Wm.
Published: December 2007

Proposal

This paper provides a summary of access and access-related legal issues for operating personnel covering access to and on oil and gas leases on federal public, Indian, state, and private lands. The author admits to a decidedly western orientation and perspective, as the western experience includes the private and state lands issues from the east and mid-continent, while adding by superimposition the federal public lands and Indian experience. These issues will cover access on the leasehold surface access of split-estate leaseholds, access over adjacent lands to the leasehold, access through mineral estates to subjacent minerals, and access during simultaneous mineral operations.
Field Experience With a New Formation Pressure Testing-During-Drilling Tool
Authors: Frank S. , Beales V. J. , Dilling S. , Meister M. , Lee J. , Haugen J.
Published: December 2007

Formation pore pressure is a key parameter for reservoir description. However, the pressure measurement traditionally performed in highly deviated or horizontal wells with drill pipe conveyed wireline tools is time consuming. To provide the measurements earlier, a formation pressure tester has been developed as part of a logging while drilling bottom hole assembly.

To meet the challenges of short station duration and limited telemetry rates, the new tool is equipped with a downhole intelligent system for real-time operational decision. The flexibility of the tool design allows basic pressure tests with preset drawdown and build-up tests with preset fixed volume and rates, or repeated drawdown and build-up tests with different drawdown rates and volumes optimised downhole in real-time.

In this first trial, the longevity and repeatability of the tool were tested. The primary requirement of the pressure data acquisition was to define the pressure profile of the well for application in the completion design. In the proximal section of the well, a zone of low pressure was identified as predicted. The real-time data quantified the reservoir pressure, which allowed the drilling engineers to optimise the mud programme and efficiently complete the drilling of the well. The tool performed well and subsequent data analyses supported the real-time pressure measurements.

One hundred forty-two pressure tests were performed at 64 different depths along the 13,673 ft reservoir section. Drilling was completed, in two bit runs, in 204 rotational hours during which the angle was built from 66° to 90° with a maximum dogleg of 3.5°/100 ft.

The successful operation of the tool resulted in considerable time/cost savings due to the optimised drilling of the well and the cancelled pipe conveyed logging job.
Reaching the Drilling Objective "Nobody Gets Hurt"
Authors: Parker Donna J.
Published: December 2007

A fundamental belief at ExxonMobil is that we can achieve a work environment in which "Nobody Gets Hurt" and we are driven to consistently articulate and relentlessly pursue this vision. Safety requires both a disciplined systematic approach and a culture where people are aligned with the vision and actively involved in its pursuit. This paper will focus on the distinct yet mutually dependent critical success factors, Safety Management and Safety Leadership, and their impact on our Drilling Contractor safety performance. Our Contractor Lost Time Incident Rate (LTIR) per 200,000 work hours was 0.06 in 2003, down 67% since 2000 and 1/10th the International Association of Drilling Contractors (IADC) average.
Surface BOP: Equipment Development for Extending the Water Depth Capability of a D.P. Semisubmersible to 10,000 ft and Beyond.
Authors: Brunt Graham , Elson Scott , Newman Tim , Toudouze Paul
Published: December 2007

The water depth operating capability of a dynamically positioned semisubmersible drilling rig normally rated for 8,100 feet, has been extended to beyond 10,000 feet by deployment of a Surface BOP, a 13 3/8" casing riser and a Subsea Disconnect System (SDS). The rig and equipment package has recently successfully drilled an exploration well in 9,474 feet water depth, representing a new record for both the operator and the host country Brazil.

This paper focuses on the 5 main features of the equipment concept, design, development and deployment:

Setting Up the Operator-Service Provider Joint Team and Alignment of Goals Defining the Functional Requirements Combination New Technology and Off The Shelf Components Description of System Units: Surface BOP, Subsea Disconnect System, Surface and Subsea Control Systems and Acoustic Digital Spread Spectrum system (ADS2). Rig Interfaces

The paper describes the output from early hazard assessment exercises used to define the basic design parameters, the selection of appropriate acoustic communication technology to provide the opportunity for future developments, risks and how they were managed, Integration Testing and Deployment.
Surface BOP: Testing and Completing Deepwater Wells Drilled With a Surface BOP Rig
Authors: Mason D. L. , Wilie C. L. , Tharp W.
Published: December 2007

Many deepwater development projects in Operators' portfolios require lower costs to meet internal economic thresholds. Shell has therefore looked at extending Surface BOP activities to include well testing and completion techniques for deepwater wells in conjunction with Surface BOP drilling.

The cost advantages of Surface BOP drilled wells have been demonstrated (notably in the Far East), but the recent Surface BOP drilled Brazil well is a milestone in terms of extending the applicability to deeper water and harsher environments. The enabling technology has been the Subsea Disconnect System (SDS). Testing and completion techniques have therefore been developed to be compatible with Surface BOP wells drilled with an SDS.

The paper will focus on the following aspects:

Well testing using Surface BOPs from a moored rig Well Completions using Surface BOPs from a moored rig

Shell has developed a testing configuration to carry out a DST essentially using standard equipment. The well testing equipment configuration is currently ready for use, waiting for the opportunity to be run.

In completion operations, the availability of a high pressure riser does not add significant complexity and even actually simplifies some of the completion activities. Conceptual studies and early hazard/risk assessments have shown there are no obvious showstoppers and the duration of a Surface BOP rig completion is expected to be very similar to a subsea BOP rig completion.

The paper describes the results of the conceptual studies, early hazard assessment exercises used to define the basic design parameters and more detailed hazop studies.
Deepwater Success Through Predictable and Distinctive Drilling and Completion Performance
Authors: Wardt John de
Published: December 2007

Benchmarked results on well construction projects show that many projects incurred significant cost over runs. Half of the mega projects since 1993 have been disasters resulting in a destruction of capital for oil companies. Insufficient drilling front-end loading and inadequate team organization have been identified as preventable causes of these over runs.

Deepwater projects involve multiple challenges of new technology, geological uncertainty and, often, a fast track approach. The wells' portion of the total project cost often exceeds 50%. The huge price for intervention activities later in the life of these wells requires that the initial completion remain in place and function as planned for a long time.

Predictable and distinctive drilling and completion performance is a must for the high cost projects that typify deepwater.

This paper will describe a methodology that has been successfully applied with repeatable best in class results in the North Sea and Gulf of Mexico. This methodology addresses the need that teams are organized to fit the project (not the other way around) and that systems integration is treated as a high priority. The results typically achieved with this methodology are in the range 20 – 23 days per 10,000 ft – best in class in both regions and 35% better than the average drilling time – with commensurate improvements in production and data acquisition. Short case histories of deepwater exploration and development wells are described – including a horizontal development well.

The paper describes:

– how the projects were organized, – how the teams were aligned to their objective and goals, – the processes that support these successful teams, – how the teams were motivated to perform, – how web based support can function to create co-location through the virtual world.

The paper also contrasts this methodology with traditional operations.
Beyond the Best Initiatives Deliver Breakthrough Performance: Deep Exploration Well, Colombia
Authors: Frazelle Andrew , Sarmiento Juan Francisco , Vargas Reynaldo , Garoby Juan , Krasuk Raul
Published: December 2007

Drilling the structurally complex overthrusted fault blocks associated with the Andes foothills of Colombia has always presented a number of distinctive challenges. Borehole instability, hard and abrasive formations, undesirable hole deviation associated with multiple fault planes and steeply dipping formations, low progress rates and frequent drill string failures are the most common problems encountered while drilling wells in the area.

In order to efficiently drill a deep exploration well in Colombia, the operator elected to implement its internal Beyond the Best (BtB) initiative to increase the chances of achieving or exceeding performance goals. A strategy was developed to anticipate challenges and address critical elements of the detailed design, the identification of the optimum well trajectory to manage subsurface hazards as well as continuous updates of the subsurface model while drilling. As a part of the Front End Loading requirements of the BtB initiative, the operator elected to engage a drilling optimization service to conduct a detailed analysis of the overburden including a critical review of drilling performance, mud logging and wireline data from reference wells. This detailed and in-depth analysis helped identify potential problems that led the operator to set optimization objectives for the upper hole sections of achieving the highest penetration rate possible while maintaining a near-vertical wellbore. An action plan with recommended solutions to overcome anticipated problems was developed and specific fit-for-purpose technologies were identified as appropriate solutions.

To introduce and build support for this new drilling philosophy and tool implementation, the operator implemented the Technical Limits Process that challenged operator and service company personnel to work as an integrated team to achieve best-in-class drilling performance using the appropriate technology. The process also encourages trust and camaraderie between team members and challenges them to feel personally responsible for delivering significant performance improvement. The authors will discuss how proper planning and understanding key issues that previously restricted drilling performance led to the identification of improved drilling practices and the application of the proper technology that resulted in breakthrough drilling performance including new world records for impregnated and PDC bits.

To measure the effectiveness of the initiatives, the authors will document savings relative to offset wells. The typical well drilled in the Colombian foothills averages 188 days per 10,000 feet to complete. However, by applying application specific technology the team has cut the average time required to drill this well to 140 days per 10,000 feet with the resultant savings in time and money to the company.
Successful Horizontal Drilling in Western Siberia: Use of Appropriate, Cost-Effective Technology Solutions to Increase Well Productivity
Authors: Diyashev Iskander , Lishchuk Vasiliy Yurivich , Aker Gokhan , Bustos Oswaldo , Prakash Leslie
Published: December 2007

The introduction of Western horizontal drilling techniques into Siberia has achieved outstanding results for Sibneft, a Russian independent operator. Before 2000, vertical or directional S-shape wells were being drilled to develop the Sibneft-NoyabrskNeftegaz oil fields using local techniques provided by Siberian drilling contractors. An alliance with a major Western service provider made possible a Western-Russian design group familiar with all available options. The group created an ideal marriage of Western and Russian fit-for-purpose equipment, procedures, and techniques for a cost-efficient horizontal well design.

The methodology applied in this project is a fusion of classic Russian drilling techniques, i.e., compact rigs skidding on a rail system with aluminum drillpipe with Russian turbines to drill tophole sections, coupled with modern horizontal technology such as steerable motors and mud pulse telemetry measurement-while-drilling (MWD) and logging-while-drilling (LWD) systems. To date, 90 wells have been drilled with a progressive learning curve enabling wells to be drilled to around 4000 m (with more than 1000 m of horizontal section) in less than 48 days that at the start of the campaign were taking more than 100 days.

The successful integration of these cost-effective solutions has been pivotal in helping Sibneft approach its production targets. Today the 90 wells drilled in the last 3 years (out of 4,500 total wells) account for approximately 175,000 BOPD, or one quarter of total Sibneft production. The cooperation of reservoir and drilling engineering teams from the service provider and the operator was critical to project accomplishments.
Novel Drilling Fluid for Through-Tubing Rotary Drilling
Authors: Franks Todd , Marshall David S.
Published: December 2007

Through-Tubing Rotary Drilling (TTRD) is a technique which has been developed to extend the production life of older fields by substantially reducing drilling costs to render smaller reserves of oil economically recoverable1. However, the small wellbore dimensions required to utilise drill-pipe inside production tubing place some unusual demands on the drilling fluid and when these are compounded by the challenges of drilling into a formation containing a large range of pressures in the reservoir and high pressure shales, a radical approach to drilling fluid design is required.

The requirement for a low viscosity fluid (to minimise ECD) which would still meet all other drilling requirements meant that conventional fluids were all unsuitable and a review of the options available resulted in the selection of a novel weighting material, manganese tetraoxide, for use in a mineral oil-based mud as the system most likely to provide the desired properties. The physical properties of commercially available manganese tetraoxide (very small, spherical particles) were known to result in very low plastic viscosities in muds made with this material when compared to muds weighted with barium sulphate. A much-reduced potential for weight material sag was an added bonus.

This paper details the design considerations of the fluid used to drill three TTRD side-track wells in Shell's North Cormorant field. Modelling of hydraulic parameters is presented, together with field results from the first well and how these led to modifications of fluid design and engineering practice which were incorporated into the subsequent wells.
Drilling Fluids for Wellbore Strengthening
Authors: Aston M. S. , Alberty M. W. , McLean M. R. , de Jong H. J. , Armagost K.
Published: December 2007

There is a clear advantage to drilling if we could strengthen the wellbore and drill at higher mud weights without losing fluid. A major prize is accessing difficult reserves in depleted reservoirs. Another application is in deep water drilling where the drilling window between pore pressure and fracture gradient is often narrow. This paper describes the approach taken by BP to produce a ‘designer mud’ which effectively increases fracture resistance whilst drilling, and which can be applied in both shale and sandstone. It works by forming a stress cage using particle bridging and an ultra-low fluid loss mud system. The theory is described and laboratory data show how the fluid system was developed. Field data are shown which quantify the increase in fracture resistance and demonstrate the value of the system. Logistics issues are discussed.
Reservoir Navigation Tool Successfully Used in a Unique Way to Determine Relative Orientation of Dual 13 3/8 in. Casing Strings in a Shared Conductor Well
Authors: Foekema Nico , Oden Ezimah , Jones Brendon
Published: December 2007

This SPE Paper describes the way that the relative orientation of two 13 3/8" casings, run in a single 32" hole, was established using azimuthal gamma sensors from a reservoir navigation tool and several radioactive PIP tags mounted in one of the casing strings. The technique uses standard oilfield equipment and has proven easy to perform. Several SPE papers have been written explaining the use of magnetic or acoustic sensors for orientation purposes, those techniques could have been used but would have been cumbersome and more expensive to use.
Improving Drilling Performance Through Systematic Analysis of Historical Data: Case Study of a Canadian Field
Authors: Adeleye A. R. , Virginillo B. K. , Iyoho A. W. , Parenteau K. , Licis Henry
Published: December 2007

Drilling operations daily generate large amounts of data but surprisingly, a significant proportion of these data are not utilized in a manner that shortens the learning curve and promotes drilling efficiency. The authors, through this paper, demonstrate how drilling analysis methodology helped identify performance gaps in a West Central Canadian field.

The above is captured under the much espoused philosophy characterized by the questions:

Where are we now? What is possible? How do we get there?

By applying this tool, significant cost savings to the tune of CAD$7.3 mln have been achieved as at the time of preparing this paper.
An Innovative Design Approach To Reduce Drill String Fatigue
Authors: Hill Tom , Ellis Sean , Lee Kang , Reynolds Nicholas , Zheng Nanjiu
Published: December 2007

Fatigue and corrosion fatigue account for the majority of drill string failures.1,2 The complexity of fatigue and the drill string designer's inability to account for a great many factors affecting the mechanism make it impractical or impossible to accurately predict a component's fatigue life in cycles to failure. This paper describes the comparative design approach. This new approach normalizes many factors affecting fatigue that are generally unknown to the designer, allowing him or her to quantitatively compare the fatigue performance of available alternatives on the basis of what he or she does know. The method has already proven effective in field use.
Effective Sand-Control Completions in a Remote Development—Chad, Africa
Authors: Witteveld Andreas D. , Cutright Derek , Hayes Joseph E. , Ellis Richard C.
Published: December 2007

Chad Development Project consists of three fields (Kome, Miandoum, and Bolobo) in the Doba basin. Completions in the Upper Cretaceous reservoirs must address the following characteristics:

Unconsolidated permeable sands (0.5 < k > 20 Darcies). Large average particle sizes (100 to 1,000 microns). Broad particle size distributions (uniformity coefficient— d10/d50—ranging from 3 to 8+). Sand layers separated by highly reactive shale. Low-gravity, high-viscosity crude oil (30 cp to 400+ cp). Separate oil/water contacts for different sand intervals. Completion interval lengths spanning a few tens of feet for a single sand to several hundred feet commingling several sands.

It is a challenge to design an efficient and reliable sand-control completion for these characteristics. Individual sand-control completion designs were evaluated by a multidisciplinary completion team (geology, reservoir, completion, and production engineers). To date, five types of sand-control completions have been used in the Chad project: high-rate water packs (HRWPs), frac packs (FPs), frac packs using shunt tubes (FPw/Shunts), FPw/Shunts and an isolation Packer (FPw/shunts&IP), and openhole stand-alone screens (OH-SAS). Only cased hole completions are addressed in this paper.

When this paper was prepared, 51 sand-control completions had been installed in Miandoum field. Initial postcompletion well performance was measured using short duration (24- to 48-hr) cleanup and test periods.

A significant learning curve for completion quality and operational efficiencies was overcome by both operations and engineering teams working together closely to improve techniques.

This paper will describe the technical and operational hurdles as well as the results achieved with various completion methods.
Technological Advances in Completion Pipe Design
Authors: Christen Brian L. , Jellison Michael J. , Tinker Steven J. , Walker Tim , Broussard Steve
Published: December 2007

New design challenges for deepwater, extended-reach and other critical completion operations have limited the use of conventional industry standard workstrings and prompted development of a new Completion Pipe capable of addressing demands for high torsional strength, gas-tight seals and a streamline connection profile.

Tubing configured with premium connections has traditionally been used to perform high-pressure completion operations. As water depths, well depths, and well angles have increased, so have the performance demands for the pipe. Torsional capabilities of premium tubing strings are often limited in these applications. Completion pipe provides the torsional strength and robustness of a high performance tool joint connection with the pressure integrity of a premium metal-to-metal gas tight seal connection.

Innovations in high-performance tubular design as well as step change improvements to existing connector technologies has led to the development of a specialized drill pipe tubular with metal-to-metal pressure seal connections as a new completion pipe option. Maximizing tool joint inside diameter and shifting tube upsets to the exterior are options for minimizing flow restrictions. The dimensional flexibility of these durable, streamlined high performance tool joints provides advantages not seen in typical API tool joints or threaded upset tubing connection configurations. Flexible connection configurations and optimized tubular design satisfy standard completion tubular profiles as well as very specific fit for purpose applications.

The paper offers solutions to completion engineers involved in planning and executing critical completion operations in deepwater, extended reach and ultra-deep wells. This paper presents key tubular design considerations for meeting torsion, tension, hydraulic, pressure integrity and pipe recovery method requirements of critical completion operations. Mechanical characteristics of assemblies and field performance of application specific completion assemblies are presented.
Wellbore Cleanup by Water Jetting and Specific Enzyme Treatments in Multilateral Wells: A Case Study
Authors: Al-Otaibi M. B. , Nasr-El-Din H. A. , Siddiqui M. A.
Published: December 2007

Many horizontal and multi-lateral wells are drilled using water-based mud in Saudi Aramco fields. Generally, the drilling fluid consists of xanthan, starch or cellulose polymers with bridging agents like sized calcium carbonate or salt particles. During drilling and completion operations it is essential to form a filter cake to control fluid losses. However, inefficient cleanup of the filter cake may lead to significant losses in well performance. Water jetting techniques and specific enzyme treatments were recently introduced in Saudi Aramco to cleanup the filter cake following drilling operations.

In multi-lateral wells in carbonate formations, the external filter cake is typically cleaned by enzyme treatments in laterals without fluid losses, whereas high-pressure water jetting is used in wells with some fluid losses. This strategy was recently applied in a tri-lateral well drilled in a carbonate reservoir. The bottom hole temperatures for the main, first and second laterals are 183, 169 and 171°F, respectively. Also, the length of the target zone for the main bore, and the two laterals ranges from 3,000 to 7,000 ft. The reservoir pressure is 2,400 – 2,500 psi.

Field data indicates that utilization of enzyme treatments and water jetting are very effective techniques in removing drilling mud filter cake. Fluid losses significantly increased during cleanup of filter cake by water jetting. Oil production reached the target value without the need to acidize the treated well. Flowback samples were collected and the nature of solids produced and their particle size distribution were measured. This paper presents various aspects of water jetting, field data and lab results based on the analysis of well flowback samples.
Issues and Solutions for Cementing Expandable Liners: A Case History
Authors: Rahman Rashid Abdul , Zulkafly Ahmad Humaizy
Published: December 2007

The oil and gas industry has in general already in place an established set of good cementing practices to meet the overall objectives of cementing. These practices have been refined and perfected over decades of industry experience in the discipline. However, new technology of expandable liners brought about its own set of cementing issues and requirements based on the equipment design constraints. Some of the requirements run counter to the established good cementing practices. This paper discusses some of the new cementing issues and requirements for expandable liners and their implications on the overall effectiveness of the cement job. Optimizing the cement job involves addressing the issues and taking a compromise between the new cementing requirements and the established good cementing practices. This paper discusses some of the available solutions for the cement job optimization with a view to meet the overall cementing objectives. Finally, a case history where the above has been successfully implemented is presented and discussed.
Increasing Effective Fracture Gradients by Managing Wellbore Temperatures
Authors: Gonzalez Manuel Eduardo , Bloys James Benjamin , Lofton John E. , Pepin Gregory Paul , Schmidt Joseph H. , Naquin Carey John , Ellis Scot Thomas , Laursen Patrick E.
Published: December 2007

Thermal effects on wellbore stresses can have a significant impact on effective fracture gradients. Changes in wellbore temperatures caused by various drilling operations provide for these thermal effects. For example, circulation on bottom usually results in lower bottom hole temperatures than the static geothermal temperature. This cooling effect reduces the wellbore stresses resulting in lower effective fracture gradients. Minimizing the cooling effect by increasing wellbore temperatures can increase effective fracture gradients and the corresponding pore pressure/fracture gradient margin avoiding costly lost circulation and additional unnecessary casing points.

This paper presents results from leak-off tests taken at various temperatures which demonstrate the thermal effect on formation stress. This paper also examines the effects of operational factors on wellbore temperatures to minimize the cooling effect and/or increase effective fracture gradients. Software developed for thermal simulation of various drilling operations was used to perform the analysis.
Shell Global Open University
Authors: Løknes Regy
Published: December 2007

Welcome. (1)

Structure.

The objective of this session is to share with you the concept of the Shell EP Global Open University. I have structured the presentation around:

Introduction, Shell External developments, Corporate universities. Description of the Global Open University, key pillars. The benefits for the business.
Use of Reliability Centered Maintenance (RCM) Analysis in Petroleum Development Oman (PDO) for Maintenance Rationalization
Authors: Khamis Busaidi , Hiren Sarma
Published: December 2007

Facing with the constant challenge for improved plant reliability at a lower cost, today's Asset Managers have been looking for various ways and means to rationalize their business activities. Being a major part of the business management system, maintenance discipline is also responding to this call. While the maintenance approach has gone through a series of evolutionary changes over the last 30 years, the managers are now looking for a more methodical and structured framework for analyzing and recommending the maintenance needs. Reliability Centered Maintenance (RCM), which takes a holistic approach encompassing integrity, health, safety, environment, financial, technology and human resources is designed to provide such a framework.

Since a large number of text books and publications are available on this subject, this article will mainly address PDO's experience in utilizing the RCM methodology through a project and some "Dos" and "Do Nots" based on the author's learning points. A brief background on the RCM methodology is provided for the readers who may not be familiar with the RCM process.
ESP Performance in Mubarraz Field
Authors: Miwa Masahiro , Yamada Yutaka , Kobayashi Osamu
Published: December 2007

Abu Dhabi Oil Co., Ltd.(ADOC) has been applying artificial lift with ESPs in Mubarraz Field, offshore Abu Dhabi, U.A.E., since 1975. In 1989, the authors published a paper which presented the trouble analysis, technical improvements and actual ESP Performance. Since then ADOC continued making efforts to increase the ESP Lifetime by applying technical improvements and countermeasure against ESP troubles. By this result, the average lifetime was increased from 2.1 years to 3 years. In particular, the longest lifetime reached is 3,617days, compared with the old record of 1,659days mentioned in the paper1).

Furthermore, detailed inspection of troubled ESPs and investigation on the new ESP units had been carried out. With intensive discussion between ADOC and the ESP manufacturer, the new ESP units were selected in 1995 and had been installed in the field.

This paper presents the technical improvement, countermeasures against the different ESP troubles including asphalten precipitation and corrosion protection, proper selection of new ESP units and actual performance of ESPs as a result of these improvements.
Innovative Completion Technology, Preparation, and Contingency Planning Simplifies Baltim Completions While Increasing Reliability and Reducing Remedial Cost
Authors: Aaty Mohamed Gharieb A. , Zuchini Ivano , Giusti F. Duke
Published: December 2007

Enhanced simplicity and reliability are critical in offshore development because of the increased costs of intervention when compared to onshore services. Therefore, many innovative equipment and operational techniques have been introduced to more effectively support these needs in offshore scenarios. For example, cut-to-release production packers provide the reliability of permanent packers but also provide capability to retrieve the entire completion without conducting costly and potentially damaging milling operations. The use of nippleless lock technology keeps the required number of landing nipples to a minimum, while providing the utility to place flow-control devices anywhere in the completion string. In addition to these and other proven completion technologies, the thorough precompletion make-up and testing procedures that are conducted for the assemblies further enhance reliability. When Petrobel began development of their offshore Baltim Field and decided to adopt the above mentioned philosophies, their effectiveness was proven very early in the campaign when leaking tubing necessitated pulling of the completion in the first well of the project.

Because of the overall success experienced in completing the Baltim wells, Petrobel is planning to use the same completion design, though modified to eliminate slickline intervention, in the upcoming Temsah Platform development.
Lower Cretaceous Stratigraphy of Abu Dhabi and the United Arab Emirates - A Reappraisal
Authors: GRANIER Bruno R.C.
Published: December 2007

This paper presents a reappraisal of the published papers on stratigraphic nomenclatures of the Lower Cretaceous rocks. Thought it focuses on the Abu Dhabi offshore areas, it also deals with coeval strata from the neighbouring emirates and countries (Oman, Qatar, etc.). A new stratigraphic classification emerged from the review of the currently used operational units in Abu Dhabi. Accordingly, the Kahmah Allogroup (the best substitute for the Thamama Group) as defined herein comprises 7 alloformations/synthems which are from top to bottom: Shu'aiba, Hawar, Kharaib, Lekhwair, Zakum, Belbazem (new name), and Bu Haseer (new name); Bab and - revised - Habshan are excluded from this allogroup and respectively transferred to Wasi'a and Sahtan allogroups. This new classification which is based on ‘unconformity-bounded units’ is supported by both biostratigraphic and sequence stratigraphic evidence. This revised stratigraphic framework suggests a new interpretation of regional basin history.
Control of Hydrogen Sulphide Scavenger Induced Scale and the Associated Challenge of Sulphide Scale Formation Within a North Sea High Temperature/High Salinity Fields Production Wells. Laboratory Evaluation to Field Application
Authors: Jordan M. M. , Mackin K. , Johnston C. J. , Feasey N. D.
Published: December 2007

Precipitation of mineral scales causes many problems in oil and gas production operations: formation damage, production losses, increased workovers in both producers and injectors, poor injection water quality and equipment failures due to under-deposit corrosion. The most common mineral scales encountered with downhole and topside processes are sulphate and carbonate-based minerals. The development over the past few years of fields where high temperature and high salinity brines are being produced with associated hydrocarbon has presented a more challenging environment for scale management. In such fields hydrogen sulphide gas is quite a common component of the produced fluids. To remove the gas from the process stream hydrogen sulphide scavengers are applied. The introduction of these chemicals can result in a secondary problem arising from their relatively high pH. Changes in localized pH associated with the introduction of such production chemicals has been observed to induce carbonate scale precipitation and in the case of one high salinity brine system unexpected sulphide scales of lead and zinc.

This paper will focus on the mechanism of occurrence of such scale types within a North Sea field and how an inhibitor package was developed that controls both carbonate and sulphide scale formation while it also effectively controls associated hydrogen sulphide. It will outline the field and laboratory testing methods utilized for assessment of the scale challenge, the chemical screening methods used and assess the currently available prediction software so that evaluation of the potential problem within fields during appraisal can be determined prior to production commencing.
Study of Calcium Carbonate Precipitation in the Near-Well Region Using 47Ca2+ as Tracer
Authors: Stamatakis E. , Haugan A. , Chatzichristos C. , Stubos A. , Muller J. , Dugstad Ø.
Published: December 2007

The present study demonstrates radioactive tracer technology as a reliable source of information in scaling experiments in porous media. The critical information obtained from such experiments is the induction time of scaling and the profile of the scale deposition along the deposition medium. In a series of calcite scaling experiments in sandpacks, 47Ca2+ was used as a tracer to monitor CaCO3 precipitation. In these experiments the induction time and the distribution of scale deposition were studied as a function of saturation ratio, temperature, flow velocity, the presence of Mg ions and the type of packing material. The results show that the radiotracer method gives a fast response to scaling events. The technique is applicable for dynamic scaling investigations in any flowing system in porous media and constitutes a valuable tool for further studies of scaling mechanisms involved in processes occurring in a variety of systems (oilfield, geothermal, desalination etc).
Inhibition of Barite Scale in the Presence Of Hydrate Inhibitors
Authors: Tomson Mason B. , Kan Amy T. , Fu Gongmin
Published: December 2007

Large volumes of hydrate inhibitors (e.g., methanol, ethanol, monoethylene glycol, and triethylene glycol as cosolvent) are added to control hydrate formation. Such practice has an adverse effect on scale formation since the mineral salts are generally less soluble in the cosolvent. Due to production from reservoirs, oilfield brines are often close to saturation as they enter a well, even a small amount of added methanol, ethanol, etc., is often sufficient to induce various minerals to precipitate, particularly the sparingly soluble minerals, e.g., barite. For example, barite solubility is reduced by as much as 20 folds, with 50% (w/w) methanol.

In this paper, barite nucleation rate were studied over a wide range of concentrations, e.g., Ba (0.5–1.8 mm) SO4 (0.5–1.8 mm) methanol (0–40%), monoethylene glycol (0–40%) or triethylene glycol (40%). Barite nucleation rate is significantly accelerated in as little as 5% (wt/wt) methanol. The barite nucleation rate can be modeled with a modified classical nucleation theory. The inhibition of barite by two phosphonate inhibitors and a polymer inhibitor in the co-solvent/brine solution is more complex. At lower co-solvent concentrations (<30% w/w), the nucleation inhibition can be predicted with a previously derived semi-empirical model that mathematically separates the effect of added inhibitors from that of the uninhibited mineral phase. At high methanol (>30%) concentration, barite nucleation may be difficult to inhibit by scale inhibitors, due to high supersaturation and the tendency of phosphonate to be precipitated as metal salt.
Inhibition of BaSO4 at a Hastelloy Metal Surface and in Solution: The Consequences of Falling Below the Minimum Inhibitor Concentration (MIC)
Authors: Graham A. L. , Vieille E. , Neville A. , Boak L. S. , Sorbie K. S.
Published: December 2007

Scale inhibition efficiency is determined in bulk jar tests in order to determine a minimum inhibitor concentration (MIC) which gives some acceptable level of inhibition (say 95%). However, this test refers principally to the bulk precipitation of barium mineral scale from solution, rather than its deposition on a surface. The complementary tube blocking test gives some insight into scale adhesion at a surface, but this is a very short residence time test. An experimental study has been conducted to examine the interactions between surface and bulk BaSO4 scaling processes in uninhibited and inhibited supersaturated brines. In this study, precipitation both in bulk and onto a Hastelloy metal surface has been studied in longer term bulk jar tests at various temperatures. It has been demonstrated that the use of PPCA at concentrations beneath the MIC level, as determined by bulk jar tests, can promote surface scaling. This comes about as a result of complex interactions between bulk precipitation and surface scaling processes and these are discussed in this paper.
Development of Oil Soluble Precipitation Squeeze Technology for Application in Low and High Water Cut Wells
Authors: Heath S. M. , Wylde J. J. , Archibald M. , Sim M. , Collins I. R.
Published: December 2007

Oilfield scale formation is dependent upon the production of water and as a result most scale inhibitors are water soluble and deployed using an aqueous phase. For treatment of wells that produce only small amounts of water and/or have water sensitive matrices and wells with high water cuts with lifting problems the use of an aqueous inhibitor can cause many problems. Even with the development of oil miscible and emulsified scale inhibitors the same problem can be encountered when the incorrect screening procedure has been used in the laboratory.

This study describes the development of a range of truly oil soluble scale inhibitors for squeeze application. A particular feature of these materials is that they preclude aqueous phases and are soluble in crude oil and diesels. The products have been designed so that is possible to deploy calcium sensitive scale inhibitors in a non-aqueous medium. Upon contact with formation water passing the near wellbore the scale inhibitor will partition into the water phase and undergo a precipitation reaction. This provides a mechanism for potentially increasing treatment lifetime.

In addition, the scale inhibitor precipitation can be further controlled and enhanced through emulsification with a calcium loaded aqueous medium also containing organic additives to aid and enhance the precipitation process. Although this involves incorporating water into the product package the invert emulsion provides an oil continuous matrix and is still considered to be significantly less damaging to water sensitive formations than standard oil dispersible and emulsified scale inhibitor packages.

A detailed investigation into the properties of selected oil soluble and emulsified products has been performed. Experimental data on compatibility with production fluids, thermal ageing, oil/water partitioning, inhibitor performance, extent of precipitation and core flood studies to evaluate formation damage potential and retention and release characteristics will be presented.

This paper will also highlight how the use of the oil soluble precipitation process can increase squeeze lifetimes when compared to traditional aqueous squeeze treatments. In addition, a new core flood procedure for the screening and evaluation of non-aqueous chemical treatments will be described and the implications this has for field application of these products will be discussed.