bluuebunny/crossref_metadata_2025 huggingface dataset:
Seamless or ERW for Sour Gas Service?
Authors: Mueller R.A. , Howden D.G.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

The shortage of seamless API standard 5L Grade B pipe, a preferred choice for sour gas service, is forcing consideration of ERW (electric resistance welded) pipe as a replacement. ERW welds, unless they are adequately post weld heat treated, can contain hard zones post weld heat treated, can contain hard zones that are susceptible to sulfide cracking. The use of metallurgical cross-sections and microhardness surveys as quality control tests are discussed as they apply to the ERW heat affected zone. The conclusion reached is that ERW pipe is satisfactory for sour gas service provided adequate quality control is maintained. provided adequate quality control is maintained

Introduction

Sour gas wellhead equipment and related gathering lines as found in East Texas, Mississippi, western Canada, and other locations are subject to failure by sulfide stress cracking mechanisms. The potential release of toxic hydrogen-sulfide gas to the atmosphere due to leaks is a major concern. Hydrogen sulfide can be fatal after a few breaths in concentrations as low as 0.1 percent. The safety record of the industry has been good, largely due to the prudent selection and quality control of both materials and fabrication techniques. Cities Service Co. has been conservative in this regard and currently specifies that only seamless API 5L Grade B pipe be used for gathering lines. Recently, seamless pipe has become more difficult to acquire with suitable delivery schedules; therefore, consideration was given to the use of electric resistance welded (ERW) pipe for sour service. pipe for sour service. Tuttle, in a paper describing selection of material for use in a sour gas environment, proposes a sound philosophy, "During engineering proposes a sound philosophy, "During engineering design, materials selection, quality control, and construction, the key issue should always be, is this item suitable for sour service? Economic considerations can be included only if this question can be answered 'Yes' on all items." Mr. Tuttle goes on to state, "Before new material is chosen for sour gas service, it should be fully tested in the laboratory and the hardness determined."

The preceding considerations become extremely pertinent, since ERW pipe is more economically attractive than seamless. Furthermore, the thinner walls available in ERW pipe permit a weight savings of steel and longer pipe permit a weight savings of steel and longer mill lengths, and require fewer field girth welds as compared with seamless. These two latter factors further increase the desire to use ERW pipe. The criterion is therefore one of suitability of ERW pipe for sour gas service, particularly as related to hardness level. particularly as related to hardness level.
Field-Scale Research on Intermittent Gas Lift
Authors: Hernandez Ali , Gasbarri Sandro , Machado Miguel , Marcano Luisana , Manzanilla Raul , Guevara Jose
Published: December 2007

Experiments on intermittent gas lift were conducted in a field scale test loop to measure: a) the effect of injection pressure, liquid column length, formation gas-liquid ratio, crude API and gas flow rate injected per cycle on the liquid fallback and b) the dynamic behavior of gas lift pilot valves.

The test loop used consisted of an 8,000-foot deep well with surface storage capacity of 3,000 Br of fluids, gas-liquid separators, surface pumps able to handle up to 12,000 Br of fluid per day, natural gas supply of 3 MMSCFD at 1,500 psig, surface and downhole pressure and temperature sensors, data acquisition system and surface control equipment.

The choice of liquid column length, gas injection pressure, size and type of pilot valves, point of injection depth and type of crude used were made based on a first set of limited tests performed at the same test site in 1996 and pressure and temperature surveys performed in more than 50 real wells in Lake Maracaibo in 1997. The survey procedure used for this work was such that the liquid fallback, along with an important number of other engineering parameters, could be obtained.

Injection pressures from 450 to 900 psi, and liquid columns from 200 to 800 ft were studied in the test loop. Two different types of crude's API were used to measure the effect of fluid viscosity on the liquid fallback for the first time. Different liquid column gradients were obtained for a particular type of crude by changing the amount of free gas present in the liquid column. In this way, the effect of the formation gas present in the liquid column on the fallback was also studied for the first time. The points of gas injection were located at 4,839 and 2,516 feet.

The dynamic behavior of both, spring loaded and nitrogen charged, gas lift pilot valves was studied using different port to bellow area ratios. As it was found in the first experimental work [1] conducted in 1996 for a limited set of conditions, the behavior of spring loaded and nitrogen charged gas lift pilot valves deviates from currently accepted theoretical behavior in opposite ways. The dynamic behavior of the gas lift pilot valves used is presented for a wide variety of operating conditions and a general analysis of the deviations found is discussed.
Predictive Models for Filter Cake Buildup and Filtrate Invasion with Non–Darcy Effects
Authors: Civan Faruk
Published: December 2007

Rapid filtration problems associated with the near-wellbore radial flow and near-fracture linear flow are modeled phenomenologically and the resulting equations of the models are solved numerically. The case studies presented demonstrate the effect of the non-Darcy flow on the filter cake thickness and filtrate volume for linear and radial filtration processes. The new models provide advantages over the previous models and provide better insights into the relevant filtration and filter cake formation processes.
Implementing Recirculation System ESPs in Gaines County, Texas
Authors: Knight J. W. , Bieschke T. M.
Published: December 2007

Design features and limitations, and operational successes and problems associated with converting selected wells in Gaines County, Texas, from rod pumps to electric submersible pump (ESP) recirculation systems which operate below the perforations are presented. Economic and operational justifications for making the conversions are addressed and limitations associated with the particular applications are discussed along with enhancements utilized in an attempt to increase run time.

The recirculation system and operational characteristics are described for two wells; one in 5½" casing and one in 7" casing, from variable speed drive (VSD) test through permanent installation. Field results indicate recirculation system ESP has increased oil production in the subject wells, with the potential to reduce downtime formerly associated with rod pumps and with shrouded motor ESP systems run below the perforations.

The field results provide additional case history to support the utility of below-the-perf operations with ESP recirculation systems to increase production in low bottomhole pressure wells, and to show the success of chemical treatments done in conjunction with submersible operations.
Applications of Diversion Techniques To Improve Gas Production in Naturally Fractured Carbonate Formations, Veracruz Field, Mexico
Authors: Perez D. R. , Huidobro E. , Navarrete R. C. , Rodriguez N.
Published: December 2007

One of the most challenging problems in stimulating multiple interval and open-hole wells is to effectively divert the acid among the intervals of interest. A new divergence technique is presented for acidizing open-hole and cased multiple interval wells of highly fractured carbonate formations with high permeability contrasts. The divergence technique uses a unique acid system, which forms a temporary barrier as it reacts with the carbonates of the formation.

Six field case histories from Veracruz, Mexico are presented, comprising open vertical and horizontal open-hole wells, and cased multiple-interval wells. The designs comprise simultaneous acid fracturing and matrix treatments of up to six intervals. The advantages of the new divergence technique with respect to conventional divergence techniques are demonstrated under challenging conditions, such as 2300 ft of open hole. The majority of the cases were traced with multiple radioactive isotopes to evaluate the effectiveness of the technique. The methodology, design and production were documented in each case.
Production Data Analysis and Forecasting Using a Comprehensive Analysis System
Authors: Poe B. D. , Zheng-Poe A. , Boney C. L.
Published: December 2007

Analysis of production data to obtain estimates of the intrinsic properties of a reservoir and of the current well condition can be performed using a number of available analysis procedures. Each of these analyses were developed using differing assumptions and often result in poor agreement between the parameter estimates obtained with each analysis when performed separately. A logical and comprehensive analysis system has been developed and used for field applications which enables the engineer to rapidly perform each of these production data analyses on the same set of production data and obtain a "best-indicated" set of parameter estimates of the reservoir and well properties. The analyses that can be performed on the production data include water control diagnostics, material balance analyses, empirical and advanced decline curve analyses using integral and derivative functions, automated history matching using analytic pressure or rate-transient solutions, and commingled reservoir production forecasting and economic evaluations. The systematic analysis of production data in this manner can be used to obtain estimates of the reservoir and well parameters for cases where other means of obtaining these values are often not available.
Artificial Neural Networks Identify Restimulation Candidates in the Red Oak Field
Authors: Shelley Robert F.
Published: December 2007

Existing wellbores represent a resource that must be properly managed for a maximum return on investment. Many of the initial completions on existing wellbores are, in some manner, deficient: stimulation is inadequate, wellbore communication with the reservoir has not been achieved, productive pay has not been included in the initial completion, or well mechanics are inadequate. Identifying restimulation candidates can be a time-consuming process because of limited personnel and resources, variability in reservoir quality, incomplete data in well files, and the lack of data for conventional wellassessment procedures. In this paper, we discuss how an artificial neural network (ANN) analysis of public information can help identify well restimulation candidates with the highest potential for production improvement.

The subject of this paper is an ANN analysis of Red Oak restimulations in Oklahoma's Latimer and Le Flore counties. Readily available and measurable well attributes were selected as inputs for ANN training. These inputs included geographical location, surface elevation, initial and current reservoir pressure estimates, perforation location, initial completion procedures, refracture procedures, current production, etc. Relevant conclusions and generalizations quantify the effect of these reservoir, well, and completion factors on the potential for production improvement. This paper documents the development of an ANN that predicted Red Oak postrecompletion production with an average absolute error less than 5% (an R2 of 0.99).
Fracturing Low-Permeability Formations in Gulf Coast Presents New Opportunities, Overlooked in the Past
Authors: Sagar Rajiv , Nemec Tom , Gray Larry , Opsal Steve , Mukherjee Hemanta , Dyson William , Morales Hugo
Published: December 2007

This paper presents a case study highlighting the process of selecting Gulf Coast of Mexico candidate wells for fracturing. The paper also describes the economical and logistical justifications used to design the most optimum fractures, the operational aspects of pumping the fracture treatment, and the pre and post fracture evaluation based on the production decline data.

In the Gulf Coast, low permeability and porosity reservoirs were routinely passed over as non-commercial. Recent advances in offshore frac-pack operations have created an abundance of equipment that make hydraulic fracture treatments feasible. The success of the fracture treatments is demonstrated in the Terrebonne (TB) 110 sand in the Caillou Island field.
Advances in Heavy Oil Lifting in the Morichal Area of Venezuela
Authors: Blann Jack R. , Garcia Roberto , Guaramata Francisco , Lozano Pilar
Published: December 2007

Although heavy oil has been produced in the Morichal area of Venezuela for over twenty-five years, significant advances have recently been made to improve performance of the heavy oil wells. These advances include new techniques for injecting a diesel diluent at the bottom of the well and further optimization of artificial lift systems. These new techniques have resulted in a significant increase in production over a short period of time with minimal outlay of resources.
The Role of Single Point Moors in the North Sea
Authors: Lenihan Jeremiah E.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

Cost effective Single Point Moors in the North Sea will require superior performance and outstanding reliability. Based on system requirements and environmental conditions major design considerations are developed. The articulated spar platform selected for the Beryl Field following these considerations is briefly described. The Single Point Moor as a component in a simplified marine transportation system is discussed and SPM performance for an assumed North Sea oil field is estimated by computer simulation. Possible development trends are pointed out.

Introduction

Throughout the last 15 years the Single Buoy Moor (SBM) has served the oil industry well and has added an improved capability in transporting crude oil and petroleum products. After some initial reluctance, the concept of tanker loading and unloading operations in waters through the use of a single mooring point has been accepted as commonplace. At the end of 1974 some 165 SBM installations had been installed or planned in widely scattered locations throughout the globe. From a single starting base the industry has developed a range of designs to cover more demanding applications and the more inclusive name of Single Point Moor (SPM) has evolved to embrace all designs of this kind.

Notwithstanding past successes, the extension of SPMs and tanker loading operations into the reaches of the North Sea brings forth a new frontier. There is a new challenge made up of functional importance, environmental severity, technological difficulty, and the ubiquitous element of costs. Naturally the experience of the last two decades will propel the efforts for the North Sea and similar areas, but the oil industry must grow from past SPM successes and not be captives of them. To highlight the SPM problem in the North Sea it is well to review the nature of the problem particularly in reference to past SPM particularly in reference to past SPM experience.
Sound Basis for North Sea Platforms - Programming of Essential Geotechnical Surveys
Authors: Krause E.R. , Mosch H.J.M.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper describes the general considerations underlying the planning of geotechnical investigations for offshore oil and gas platforms.

The investigations are split into three phases. The first phase consists of a site selection survey; the second phase deals with detailed surveys at specific sites, and the third phase includes laboratory testing, foundation analysis, construction planning and foundation evaluation. Details are given of the scope of the investigations and the equipment which can be used.

Introduction

oil companies, developing offshore hydrocarbon fields are bound to time frames. As far as the geotechnical consultant is concerned, these schedules run from the first commercially exploitable strike through the phase of final design to the installation and subsequent operation of the offshore facilities. The consulting geotechnical surveyor must meet the target dates set by the oil companies, so that sufficient information is available first when decisions on the number, type and lay-out of structures have to be made and later during the design and construction phases.

THE PROCESS OF PLANNING AND DESIGN OF OIL/GAS FACILITIES

Reservoir engineers and civil engineers jointly consider the layout, number and type of the production facilities. This takes production facilities. This takes place in stages in the period between place in stages in the period between the first commercial exploitable strike, the sinking of additional step-out wells and the consequential reservoir evaluation. As more information becomes available, the civil engineer can consider alternatives as to the most suitable sites, within the leeway given by the reservoir engineer, and the types of structures. The final lay-out and choice of the structures will be a compromise between both civil and reservoir engineering requirements. Once this has been completed, the final design work can start.
Application of Chemical and Microbiological Data for Sulfide Control
Authors: Morris Edgar Alan , Gomez Rick , Peterson Roger
Published: December 2007

Hydrogen sulfide souring in oil and gas reservoirs due to sulfate-reducing bacteria (SRB) has been well documented, and the awareness of the problem is widespread in the industry. Reser-voir engineers often specify preventive subsurface biocide treatment where progressive souring has the potential to occur. This strategy has the advantage of attaining early control of microbial communities that may eventually cause souring. The disadvantages include cost, environmental, and worker-safety considerations. In addition, the reservoir engineer cannot be certain that down-hole treatment is necessary without specific chemical and microbiological information on the system treated.

In a study sponsored by Northern Natural Gas (an Enron Company), a group of wells in a natural gas storage field having a history of souring was evaluated. Wells in the reservoir had been biocide treated for many years and some eventually went sour. The wells studied remained sweet although they had been expected to eventually go sour. Microbiological and chemical analysis of these wells revealed that, unlike the sour counterparts, little potential existed for them to go sour. The subject wells exhibited limited nutrients available for SRB, and other bacteria were identified in the produced water that naturally inhibit sulfide production. The study was extended to three additional natural gas storage facilities, utilizing the same formation, and similar correlations were shown between bacteria, nutrients, and sulfide production, although the fundamental water-quality parameters were different. The sponsor of the study has utilized these findings to curtail unnecessary treatment.
Mitigating in a Sensitive Environment, Overcoming Logistics with Technology: Bird Island Mitigation Project, Upper Laguna Madre, Texas
Authors: Graham Alexandra L.
Published: December 2007

Fina Oil and Chemical Company is currently involved in a mitigation project which consists of two phases: earthwork and seagrass replanting. The Bird Island Mitigation Project is part of a mutual agreement between Fina and the US Army Corps of Engineers in retribution for seagrass damage in a 37 acre area during mobilization of a drilling rig to location in 1990.

The site is located in the Upper Laguna Madre, between the southern coast of Texas and Padre Island. It is among the largest of three high-salinity lagoons in the world and also one of the world's rarest marine environments. This area's extreme environmental sensitivity, coupled with an average water depth of 3 feet, caused deriving successful mitigation plans to be difficult.

The objective of the project was to place fill and recondition the bay bottom in two areas creating proper seagrass habitat. Upon completion of the earthwork, 74 acres of seagrasses would have to be harvested and planted in the habitat created.

This paper provides a chronological depiction of the development and procedure of one of the largest restoration and mitigation projects of its kind. Highlighted, are the new technologies researched, developed and tested to aid in the development and implementation of the earthwork phase completed in May 1998. This was the most challenging and difficult phase of the mitigation project.

Research conducted produced the negative effects of hydraulic dredging plumes on the environment. Studies show that plumes both distribute and re-supply areas with necessary nutrients, but consequently, block light penetration due to the suspended particles. Critical research concentrated on techniques developed primarily for hazardous substances and technology responsible for transportation of dried commodities. Both techniques researched minimized turbidity plumes and allowed for timely completion.
Polyaromatic Hydrocarbon Content in Crude Oils Around the World
Authors: Kerr J. M. , Melton H. R. , McMillen S. J. , Magaw R. I. , Naughton G.
Published: December 2007

Polyaromatic hydrocarbons (PAHs) are of environmental concern because a few of them have been found to be mutagenic and/or carcinogenic at some dose levels in laboratory studies. For this reason, 16 PAHs are on the U.S. Environmental Protection Agency's Superfund Amendments and Reauthorization Act (SARA) Priority Pollutant list (U.S. EPA 1987). PAHs consist of two or more fused benzene rings in linear, angular, or clustered arrangements. They are naturally occurring in crude oils and therefore may be of concern at crude oil spill sites and in some types of E&P wastes. There are many sources of PAHs in the environment with incomplete combustion of fossil fuels (including coal and oil) being a major source of low concentrations of PAHs worldwide. Some other environmental sources of PAHs are natural oil seeps, spills of refined products, and wood preservatives such as creosote.

Exxon Production Research and Chevron Research and Technology as participants in a joint industry effort through the Petroleum Environmental Research Forum Project 97-08 have analyzed over 48 crude oils, exploration and production (E&P) wastes, and site soils from across the world. In this paper, information regarding PAH content and concentration is compared to the composition of some refined products, creosote, and combustion sources. The potential risk to human health from PAHs in crude oils is also addressed. Preliminary assessments were conducted to determine the concentrations of these crude oils in soil for which human health risk from PAH exposure was acceptable. The concentrations determined from these assessments were compared to total petroleum hydrocarbons (TPH) cleanup criteria targets of 10,000 ppm, as used by several states. For all oils tested, the cleanup standard of 10,000 ppm was protective of human health with a considerable safety factor.
Framework for a Comparative Environmental Assessment of Drilling Fluids Used Offshore
Authors: Meinhold Anne F.
Published: December 2007

In response to effluent limitation guidelines promulgated by the United States Environmental Protection Agency, industry has developed alternatives to the water and oil-based drilling fluids used offshore. These synthetic-based muds (SBMs), enhanced mineral oils (EMOs) and purified paraffin oils have lower toxicity and smaller environmental impacts than diesel or conventional mineral oil-based muds (OBMs). EPA is developing new guidelines for the discharge of these fluids and the associated cuttings. The decision about allowing or disallowing the discharge of cuttings with small amounts of associated SBMs, EMOs and purified paraffin oils should not be based solely on potential environmental impacts, especially those such as bioaccumulation or biodegradation that may not be directly connected to effects on populations or ecosystems. Regulatory decisions about drilling fluid discharges should also consider potential impacts associated with the alterna-tives; including occupational accidents and chemical expo-sures, impacts associated with disposal, air emissions, and transportation risks. Because these new fluids are expensive, industry will not continue to use them if the cuttings cannot be discharged offshore. The alternative to allowing the discharge of these new drilling fluids is the continuing use of OBMs in difficult drilling situations. This paper develops a framework for a comparative environmental assessment for the discharge of drilling fluids, to help support a risk-based, integrated approach to regulatory decision making.
Silica Micro-encapsulation: A Technology for the Elimination of the Environmental Impact of Cutting Discharges
Authors: Limia Jose M.
Published: December 2007

A new approach is required in order to eliminate the environmental impact of the discharge of cuttings contaminated with invert emulsion drilling fluids. Up to now, much emphasis has been given to the inherent environmental characteristics of the fluids themselves (toxicity, biodegradability, etc.) but little or no attention has been dedicated to the mechanisms of environmental impact

The main mechanism of impact of the discharge of drilled cuttings is the organic enrichment of the marine sediment. Organic enrichment is a situation derived from the accumulation of organic matter in concentrations exceeding the "processing capacity" of the receiving environment (the oxygen demand exceeds the supply).

Silica Micro-Encapsulation will eliminate the possibility of organic enrichment as well as the direct toxic effects of the fluids coating the discharged cuttings. Once the oil attached to the cuttings is encapsulated, the cuttings become water wetted, which leads to their dispersion in the water column (as it is the case with water based mud cuttings). The dispersion of the cuttings will minimize the load of fluid in the sediment. In addition, the encapsulated oil is not bio-available, therefore these cuttings will not have an oxygen demand which will prevent the organic enrichment.
Well Control Guidelines for Girassol
Authors: Bertin D. , Lassus-Dessus J. , Lopez B.
Published: December 2007

The Girassol field, discovered in 1996, lies offshore Angola in water depths around 1350 m. The development project calls for the drilling of 40 subsea wells which will target shallow oil bearing tertiary reservoirs constituted of highly permeable unconsolidated sand layers. Although pore pressure is hydrostatic, well control is an issue, as there is a high swab kick risk, mainly for the long horizontal wells. This paper reviews some essential particularities of West Africa deep water drilling operations which make well control challenging; the objective is to highlight key parameters related to well control situations in this environment such as low temperatures, very low fracture gradient, problems induced by the risk of major lost circulation, and all the consequences of the BOP position at mudline, sometimes nearer to well TD than to surface. A new theoretical control approach is proposed, based on the classical Driller's method, offering an optimized choice of the slow circulating rate and some easy-to-follow control curves. A graphical synthesis associated with the essential equations of the wellbore pressures at the different stages of the control operation will be detailed. This method intends to be fully efficient even in extreme situations such as a swab gas influx in a long horizontal drain with significant choke line pressure losses. Validation has been made by using an advanced kick simulator. The objective is to propose to Girassol operations staff a new type of kill sheet. New operational well control guidelines, combining essentially the experience gained while drilling Angola Bloc 17 exploration and appraisal wells, and the theoretical approach already introduced, are also presented in this paper.
Conductor System Design For A Deep Water Jackup in Cantilever Mode Over the ETAP Platforms
Authors: Burton K. , Odgers M. J. , Nehring C. , Boon W.
Published: December 2007

Increasingly, field developments in the 0 m – 100 m depth range are utilising deep water, harsh environment jackups in cantilever mode over fixed platforms near to their operating limits. In such water depths, it is possible that there will be substantial relative movements between the jackup and fixed platform, under the action of environmental wind, wave and current loading. Any such relative movements cause very high loadings within the conductor system, in the surface equipment and on the jacket guides; indeed, such loadings are often in excess of those caused by environmental loading on the conductors themselves. Consequently, all of the above loadings must be accounted for in the design process, in appropriate combinations.

The above issues were addressed in the design of conductor systems for two platforms located the United Kingdom Continental Shelf (UKCS) Central North Sea (CNS). The platforms were Marnock and Mungo, which form part of the ETAP development. A thorough understanding of the key issues were developed, and analytical and design solutions prepared to maximise drilling operability. Operating procedures were prepared, to ensure that the conductor systems will remain within acceptable operating envelopes. These procedures are now being used in the field.

The purpose of this paper is to briefly describe the analytical work which was performed for both Marnock and Mungo, summarise the key issues, and outline the operating procedures that were developed (by the ETAP project) to manage the integrity of the conductor systems. Also contained in the paper is an outline of the topics which should be addressed when designing such systems for use from deep water jackups, working in cantilever mode (over fixed platforms).

Though each jackup/conductor/platform combination is unique, the novel techniques described in this paper will be applicable to other projects, where similar systems are being considered.
Development and Implementation of a Process That Fosters Organizational Learning
Authors: Morgan D. R. , Willis J. C. , Lindley B. C.
Published: December 2007

How can an operator consistently deliver best in class drilling performance around the world? Phillips formed a Critical Well Improvement Team (CWIT) to answer this question. This team included representatives from each of its E & P business units and from every discipline involved in drilling projects. The team critically looked at the processes used in planning and executing drilling projects and examined the obstacles that stood in the way of consistently delivering best in class wells. This lead to the development of the MaxWell, short for Maximum Well Value, Process.

The MaxWell process includes a consistent methodology to be used in planning, executing and post well analysis of drilling projects. In addition, it introduces a common filing structure, a common format for documents generated by a drilling project, and a method for sharing lessons learned on a global scale. MaxWell also includes a staffing template to help each division identify the personnel resources required to deliver best in class drilling results.

This paper will discuss the steps the CWIT took to develop MaxWell, the MaxWell process itself, and the care taken in developing an implementation plan to insure that MaxWell becomes a part of the well planning culture and does not become another forgotten initiative.
Win90's: The Evolution of a Partnership
Authors: Lane Ian , Richards Simon
Published: December 2007

This paper represents the views of two parties seeking to optimise a working partnership. It represents the "official" view of neither operator nor contractor.

Industry has interpreted partnership in many different ways, from alliances to lead contractors, incentive through gainshare. In the late 80's, Shell Expro embarked on a strategy of contracting out the execution of drilling and the management of many associated services on its North Sea installations via a "lead contractor". Perception of its effectiveness throughout the next decade covered the whole spectrum of opinion. Supporters highlighted the potential for reduced overheads, performance improvement and focus on core business. Detractors highlighted increases in "hidden" overheads, loss of control and reduction in performance focus.

This paper then describes the evolution of a working relationship between operator and contractor from the initial implementation period when Win 90's was being forcefully promoted throughout the industry, through the development of a workable and working partnership, and looks forward to what the future may hold. Contractual issues, incentivisation, organisational issues, other environmental factors as well as performance, are all examined during the course of the paper.
Safety Can't Wait: A Global Campaign for Transformational Change
Authors: Buchan Rob
Published: December 2007

The statistics tell a sobering story, about half the lost time injuries in our industry occur on drilling rigs. Industry trends indicate drilling safety performance is on a plateau and there is a growing belief that the current performance isn't good enough. Faced with this information we have two choices. The first is to do what we do already and accept the inevitable consequence that we will continue to have accidents. The second is to realise that, as an industry, we need to do something different if we are to create a culture where an accident free drilling operation is common place.

This paper describes a process for revealing the underlying culture of the drilling industry and the type of behavioural and organisational changes which need to be made if we are to achieve a permanent step change in safety culture and performance.

In the same context the paper describes the global drilling safety leadership campaign which has been initiated to enroll operators, drilling contractors and service companies to the common cause of improving drilling safety performance by working together on personal commitment, leadership and behaviour.
Best Completion Practices
Authors: Dyson William Q. , Coludrovich Earl , Weldy John C. , Fruge Michael , Guidry Marlon
Published: December 2007

Over one hundred Gulf of Mexico completions have been analyzed over a period of two years, resulting in the best practices, as outlined in this paper. The completions have been categorized into ten different types, and optimized methods for implementing each type are listed. Completion engineers, production engineers, rig foremen and many service company personnel have contributed to Best Completion Practices. The work, however, has mainly been driven by an Alliance Process Improvement Team (APIT) composed of the authors, thus shared visions and solutions are the means by which common completion objectives have been reached.
Analysis of the Stick-Slip Phenomenon Using Downhole Drillstring Rotation Data
Authors: Robnett E. W. , Hood J. A. , Heisig G. , Macpherson J. D.
Published: December 2007

The stick-slip phenomenon has been identified in the industry as an inefficient and often damaging drilling vibrational condition. Numerous studies, predominantly focusing on measurements of drillstring torque, have detailed the nature of this phenomenon, and have shown its detrimental effects on drillstring components and especially on PDC bits. Using surface rotary motor current, drilling contractors and surface logging companies have attempted to monitor drillstring torque so as to recognize and correct for this torsional instability.

Recent MWD tool developments using downhole drillstring rotational speed have established a superior method to identify stick-slip and establish its severity. Measuring actual rotational behavior of the lower BHA gives a better insight to the torsional movement of the drill bit during the drilling process, without the problems involved when inferring this behavior from the surface torque readings, obtained at the opposite end of the drillstring.

This paper describes the method of determining the stickslip behavior downhole from magnetometer readings. The sensors are sampled at a high enough frequency to compute nearinstantaneous values of downhole drillstring rotation, and variations in the RPM are then used to establish the incidence and severity of stick-slip. This information is telemetered to the surface and provided to the driller in order to allow for real-time changes in drilling parameters to correct for this inefficiency. Also presented in the paper are several examples using actual field data that detail stick-slip behavior and demonstrate how real-time information about downhole RPM variations can help to reduce the problems associated with this torsional drilling dysfunction.
Innovative use of BHAs and LWD Measurements to Optimize Placement of Horizontal Laterals
Authors: Farruggio G. , Rasmus J. , Low S. , Ingold C. , Jackson K. , Curtis C.
Published: December 2007

More than 50 horizontal laterals averaging 4600 feet in length have been drilled in a shallow, heavy oil reservoir in eastern Venezuela. Precise navigation through the formations was necessary to optimize placement of the lateral drainholes and maximize the percentage of reservoir sand exposed. To meet this requirement, an optimized bottom hole assembly (BHA) design and logging while drilling (LWD) interpretation technique were developed based on field experience.

Measurement while drilling (MWD) continuous directional measurements were used to steer the well through the reservoir, along a specific well path chosen from three-dimensional (3D) seismic that covers the field area. The LWD azimuthal and bit electrode measurements were integrated with the 3D seismic to allow an interactive interpretation of the stratal boundaries present within the reservoir which resulted in continual refinements to the planned well path. Using the information derived from the LWD azimuthal and bit electrode measurements, the location of shale stringers, bed boundaries, and pay sand relative to the BHA could be determined and the well then steered in the appropriate direction to maintain an optimum position within the oil reservoir.

As a result, the number of sidetracks was reduced and the percent sand encountered increased. The longest horizontal lateral in Venezuela was also drilled and completed as part of this project.
Special Requirements for Maintenance of Mechanical Equipment in the North Sea
Authors: Larson James C.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

Considerations regarding maintainability of equipment in the early phases of platform design as well as effective maintenance and parts support programs are presented to satisfy parts support programs are presented to satisfy the unique mechanical equipment maintenance requirements dictated by the North Sea environment.

Introduction

Because of the hostile environment and rather unique logistics problems prevalent in the North Sea, normal maintenance practices, to which most of us have been accustomed, are not quite sufficient. There are many reasons for this. Let's look at the more important ones.Weather - Historically, for 5 or 6 months of each year, wind and wave conditions in the North Sea are such that transportation of necessary material and supplies is extremely unpredictable. Loading and offloading by supply boats can be delayed for up to 7 days at a time due to weather. Transportation of emergency items must be made using hell copters during these periods. This is expensive and limited by size and weight of items the helicopter can carry.Communications - The various items of production equipment purchased and installed on production equipment purchased and installed on North Sea platforms originate in almost all of the industrialized countries of the world. When a problem arises with any equipment item that cannot be readily solved internally, the normal solution is to contact the original manufacturer or representative and expect to get help or service personnel usually within 24 hours. Eventually this will be the case in the North Sea, but today communication with manufacturer parts and service organizations is a real parts and service organizations is a real Problem due to lack of knowledgeable local Problem due to lack of knowledgeable local representation of original equipment manufacturers.Personnel Requirements - Because of the tremendous concentration of drilling and production activity in the North Sea today, production activity in the North Sea today, the operating companies and service support organizations have summoned technical, supervisory and craft personnel from all over the world to satisfy the manpower requirements. Many of these people are not familiar with or not presently qualified to handle the type of equipment in use on North Sea platforms. Specialized training of personnel or use of contract specially groups is required to successfully operate and maintain North Sea production systems and mechanical equipment. production systems and mechanical equipment.4. Unique Equipment Requirements - You might ask yourself, at this point, what is so different about the equipment used in North Sea production as compared to other areas in the production as compared to other areas in the offshore industry?
Steels For Refinery Equipment
Authors: Samans Carl H.
Published: December 2007

Selection of steels for petroleum refinery vessels and piping is determined by the most economical combination of code allowable stresses and ability to resist service deterioration under operating conditions. Temperature is a major factor in selection because it effects both strength and corrosion rate; refinery operating temperatures may range from -50 degrees F or lower to 1200 degrees F or higher depending on the process. Hydrogen deteriorates some steels over much of this range but the mechanism of attack varies with temperature. Design stresses for many steels are constant in the range -20 degrees F to 650 degrees F, but at and below atmospheric temperatures ferritic steels may undergo a notch-brittle transition; the probability of this hazard must be recognized. From 650 degrees F to 1200 degrees F, ferritic steels containing up to 9 percent chromium and 1 percent molybdenum resist most forms of deterioration successfully. The higher chromium ferritic steels have little merit. Above 1200 degrees F, and for severely corrosive conditions at lower temperatures, austenitic stainless steels must be used.
Using Learning Models to Capture Dynamic Complexity in Petroleum Exploration
Authors: Gallant Lawrence , Kieffel Hervé , Chatwin Richard
Published: December 2007

Large-scale petroleum projects require capital investments and operating decisions that stretch out over many years. Estimating the profitability of such ventures is a complex task, usually requiring significant time and effort Firms typically produce spreadsheet-based cash-flow models that provide extensive detail on the costs associated with a project This paper asserts that decision-making about large investments is improved by focusing less on such "detail complexity"—drilling down into data to achieve greater detail and precision—and more on dynamic complexity. By dynamic complexity we mean the dynamics of how conditions will change over time and, equally important, how you can manage a venture to adapt to those changing conditions as they emerge.

The key element in planning an adaptive strategy is that you learn about major sources of uncertainty as they develop. Sources of uncertainty include oil prices, reserves levels, operating performance, and competitors' actions. Correctly evaluating adaptive strategies requires that you exploit newly acquired knowledge about evolving conditions to make better informed decisions. This paper discusses the importance of dynamic complexity in valuing petroleum projects and the vital role that learning models play in capturing such complexity. Several examples from exploration and production projects will be presented.
Probabilistic Play Analysis From Geoscience to Economics: An Example From the Gulf of Mexico
Authors: Moore L. R. , Mudford B. S.
Published: December 2007

Play analysis is not a new concept. However, the use of probabilistic economic analysis techniques and tools can add a new dimension to the assessment of the economic value captured when entering a new play. Over the past decade there has been considerable effort devoted to modeling the economics of hydrocarbon plays. Describing the reserves in each prospect probabilistically, and setting dependencies between geologic risk factors in the prospects to compute a composite geologic probability of success is a frequently applied method. However, the play economics are often done simplistically by computing the value based on a mean development scenario, or an assumed ratio of net present value to oil-equivalent volume.

We will show how more rigorous probabilistic economics can be folded in with the standard probabilistic reserve assessment. Once hydrocarbons are found, there are generally one or more possible development scenarios depending on reserve size and production rates. By assigning probability distributions to the engineering elements of production rates and declines, investments and expenses, distributions of economic indicators such as NPV, ROR and P/I can be calculated. Conditional logic is used to build all possible development scenarios into a single probabilistic model, which can take the place of multiple decision tree cases. Such a model can be used to investigate the inherent risks and provide probabilities of achieving a positive NPV for the play, or of adding a certain volume of reserves.

In this paper we will present a Gulf of Mexico play model as an example. In this play the number of prospects has a probability distribution. In addition, we cease exploration in the play if three consecutive dry holes are drilled. For each prospect in the play we have an economic threshold. Below this threshold we abandon the prospect and incur dry hole costs. There is also a development threshold that determines whether the development uses subsea completions, or a platform. For each development scenario the production rates, investments and operating expenses are modelled as probability distributions.

Once a robust probabilistic model is built, the sensitivity of the model to the uncertainties in many variables can be readily investigated. A powerful feature of this model is that the impact on the play economics of factors such as delays can be quantified.