bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation & Mitigation of "Metallic Soap" Sludge, Attaka, Indonesia Field
Authors: Gallup Darrell L. , Smith P. Colin , Chipponeri John , Abuyazid Ainul , Mulyono Djoko
Published: December 2007

Greenish-brown sludge is formed in significant quantities during production of oil and water from the Serang field, offshore East Kalimantan, Indonesia. This interfacial sludge is comprised of entrained free oil, water and solids, and is stabilized by material described as a "metallic soap." In the absence of fluid treatment, removal and disposal of the sludge is tedious, expensive, and represents significant un-recovered oil.

The sludge was carefully characterized to understand its formation mechanism, so that remedial actions could be taken to mitigate its deposition. The sludge was characterized by elemental analyses, x-ray diffraction, nuclear magnetic resonance, Fourier transform infra-red spectroscopy, gas chromatography-mass spectrometry, and scanning electron microscopy. The results of the characterization studies suggest that sludge filtered and dried at 100°C (to remove free oil and water) consists of ~70 wt% branched and straight chain hydrocarbons in the range of C14 – C28. About 20 wt% of the sludge consists of C28 – C30 carboxylate salts and <5 wt% is inorganic minerals. Emulsification of oil, water droplets and solids by carboxylate salts and bicarbonate ions from water is the most likely sludge formation mechanism. Laboratory and field tests have demonstrated that the sludge can be dissolved by low dosages of commercially available sludge dissolving agents containing combinations of acids. As a result of dissolving the sludge, incremental oil is recovered, which offsets chemical treatment and sludge disposal costs. Although the sludge may be dissolved at the Santan onshore processing facility (end-of-pipe), sludge formation is best mitigated by treating the point-of-source at the Serang offshore platform.
Project Economics and Permissible Environmental Cost
Authors: Agbon I. S.
Published: December 2007

An urgent issue facing the oil and gas industry today is how much each stakeholder should pay for the environmental pollution resulting from oil and gas operations. The oil producing companies argue that all the stakeholders should share the cost. Some stakeholders, like the host national government and the host communities, disagree. They insist that the oil companies should bear the full financial responsibility for the environmental pollution. Hence, how much the oil company can pay for the environmental pollution becomes a very important question.

This paper determines the permissible cost of environmental pollution for any oil and gas project. Using a modified conventional project economic profitability model, the affordable cost of environmental pollution is estimated. Sensitivity analyses are carried out for parameters such as oil price and internal rate of return. The paper concludes that the permissible environmental cost should be a project screening criterion for all future oil and gas projects.
The Safety Coach: Reinventing the Field HSE Professional
Authors: Sealy I. , Engel H. , Cocking D. , Haynes J
Published: December 2007

In recent years, Exploration and Production (E&P) and contractor organizations have adopted management systems as their primary tool for Health, Safety and Environment (HSE) performance delivery. Consequently, HSE personnel in field operations support roles have found that their time is increasingly consumed by systems support tasks. Confronted by these demands on established HSE staff and by static, or deteriorating, HSE outputs, we identified that a completely different approach was required to provide HSE support to field operations groups. We believe that this new approach offers significant advantages when compared with—and also complements—the role of conventional HSE personnel.

This paper describes how we created and implemented the role of the Safety Coach. Stripped of almost all administrative and systems-support responsibilities, the Safety Coach provides mentoring, audit, inspection and risk management support directly to field operations crews at the wellsite. Our experience shows that the Safety Coach delivers significant improvements in both input (leading) and output (lagging) HSE performance indicators.

This paper defines the role and responsibilities for the Safety Coach position. It describes selecting personnel and setting performance metrics and performance targets. It reviews HSE performance for operations groups that have been supported by a Safety Coach position and compares that performance with operations groups in the same service company organization that have not been supported by a Safety Coach.
Taking Health to Remote Host Communities: Our RiverBoat Clinic Experience
Authors: Ajayi Pa , Fagade O. A. , Kpiasi O , Faleyimu B. L.
Published: December 2007

Taking Health to remote Host Communities: Our RiverBoat Clinic experience.

Arising from a desire to positively impact the lives of people in its areas of operation, Chevron Nigeria, on behalf of the NNPC/Chevron Joint Venture, in 1992 built and commissioned a model 18-bedded community health facility - the Ugborodo Community Cottage Hospital for its host communities in the Niger Delta region of Nigeria1. This hospital which served about seven villages with an estimated total population of 60,000, located round Chevron's Escravos Tank Farm, provided emergency and primary health care free of charge, and was in fact the only health facility available and accessible to the host communities. This hospital was burnt down during one of the inter-ethnic communal crises in May 1999, and plans for its rebuilding have advanced. Continued provision of healthcare services to these communities became a major challenge. In January 2001, Chevron built and commissioned a riverboat ambulance, which has become of immense value in providing healthcare to these communities in the difficult mangrove terrain of the company's area of operation.

This mobile health facility runs regular scheduled visits to the various communities and is able to cover a wide area. It is well accepted and highly valued by the host communities.

It is run in partnership with the Delta State Government of Nigeria and the relevant local government authorities; benefiting communities are encouraged to play active roles in this program.

A memorandum of understanding was signed between Chevron, the State government and representatives of host communities to define scope of the service and assign roles to the key players.

This paper will discuss the mode of operation of the riverboat clinic, the scope of its services, community perception and participation, opportunities it has provided for partnering with government and host communities as well as the common medical problems encountered with other relevant data.
Health Performance Indicators
Authors: Smith D
Published: December 2007

In an effort to protect and improve the health of personnel involved in upstream oil and gas activities, the industry has, for the first time, started to collect Health Performance Indicators (HPI) from its operations around the world.

Pro-active and reactive indicators are being collected. The pro-active indicators focus on the number and nature of the health risk assessments an organisation has undertaken (eg number of site visits by health professionals, ergonomic assessments and community impact assessments). The reactive indicators measure incident rates expressed in terms of Occupational Illness Categories (e.g. back problems and lower limb disorders, mental ill-health and noise induced hearing loss).

The paper presents the results and the lessons learnt from the year 2000 HPI data collection programme.

Eight organisations, seven of which are OGP members, provided HPI data in varying levels of detail. Initial analysis of the data indicates a predominance of health problems associated with back, neck and lower/upper limb disorders. Infections/preventable diseases and mental ill-health problems also feature as a major contributor to the health statistics.

The paper presents the approach being adopted by the industry to improve the quantity and quality of the data to be collected in future years. In particular it is recognised that there is a requirement to define better certain parameters, such as what constitutes a valid and reasonable health risk assessment.
Inconsistencies with Statistical Incident Reporting
Authors: Huebler Vicki L.
Published: December 2007

Today, so much is measured! We are constantly challenging ourselves for better, faster and more efficient results. However, the way we count our incident statistics is not consistent, and all of us, in all industries, are measured against these indicators. Future jobs, contracts and, in many cases, personal incentives ride on these numbers.

This paper exposes some of the differences in the definitions and resulting frequency rates. The intent is to highlight the differences in the numbers for which we are responsible. Minor definitional differences show how frequency rates can be affected, especially when making comparisons.

This paper also stresses the need to move forward with the development of a standard reporting system. We know that we must continue to reduce incidents. However, to truly measure performance, we must first acknowledge the incident, measure consistently and accurately, and then promote measures to prevent recurrence.
Reducing Risk of Oilfield Chemicals to Marine Environments – Development Practices, Achievements and Benefits
Authors: Hill Donald G. , Dismuke Keith , Shepherd William , Romijn Henk , Witt Irena , Wennberg K. E. , Poitrenaud Hugues , Gruner Hans , Perez Daniel
Published: December 2007

This paper presents the results of aggressive chemical development and replacement programs for stimulation chemicals for worldwide application. Developing more environmentally acceptable products requires working with regulatory agencies, clients and chemical suppliers to achieve compliance with relevant international statutes, such as environmental, occupational, transportation, and trade control for Material Safety Data Sheets (MSDSs), labels and environmental testing protocol. Technical achievements are only realized by continued commitment and product improvements to meet or exceed Health, Safety and Environment (HSE) goals.

One oilfield service company's approach to the global issue of chemical management, based mainly on North Sea experience in wellbore stimulation, is described. The guidelines and process for product development or replacement are outlined and presented. The program ensured that Quality, Health, Safety and Environment (QHSE) issues were kept at the forefront in the product lifecycle development and management process.

This paper recognizes that international environmental statutes and guidelines are the strongest driving force to restrict industrial use and discharge of environmentally harmful chemicals. The development of more environmentally acceptable products requires a thorough screening of environmental fitness and status of compliance with relevant laws and regulations. The environmental improvement initiative addresses human health as well. Results of the program verify that environmentally improved products can be efficient, as well as cost effective.

This paper presents 3 years of field results achieved using environmentally improved stimulation products in the North Sea area. Oilfield chemicals used in the study were replacement products designed through an aggressive program to address environmental opportunities and issues in product development and application. Case histories from the Heidrun field in northern Norwegian sector, 75 mi from the Arctic Circle, and stimulation operations in the Valhall field in southern Norway are presented.
Sharing the Akassa Process: 5 Years of Building Partnerships and Seeking Sustainability in the Niger Delta
Authors: Knight Bill , Alagoa Nalaguo Chris
Published: December 2007

After five years of experimentation in Nigeria's troubled oil-producing Niger Delta, unlikely but remarkable partners who typically won’t work together are doing just that! Though in some cases this strange alliance is limited to funding, the emphasis is less on patronage than on partnership, more on sustainability than short-term success.

The leaders of the process are the Akassa Clan. Central to the process, needing both peace and having a clear exit strategy, is the oil industry. An NGO facilitates, assisted by local and international volunteers and occasional consultants from a state university. It is a deliberately participatory process, involving all corners of the Clan in problem analysis and decision-making. In the mangroves, ill-educated village people ponder, plan and plunk-out project proposals on their programme's second-hand computers, persuading people to partner them in the implementation of Akassa's Development Programme.

Gradually they have drawn into the process numerous stakeholders with wide-ranging social concerns and academic or other interests but perhaps little in common. In Akassa, these oil men, academics, scientists, businessmen and volunteers, governments and donors, variously help ordinary villagers to focus on common problems, promoting income generation through eco-tourism or primary health care by capacity-building. Drag these bodies to a round table and they might not even talk to each other. In Akassa, they actively partner a local cause!

Results, Conclusions

This has not been an un-troubled, fault-free nor easy process but it has proceeded beyond questioning: ‘Will it work?’ It does! Now the questions are: ‘Is it sustainable?’ ‘Can it be replicated?’

In the long term, the Akassa will decide these questions themselves by respecting or breaking the forest and fisheries bye-laws they themselves are making as part of this process, or by building and managing the training centre they want instead of ‘chopping’ the donors' funding. Watchful, their neighbours are deciding whether they should extend the process. Some, with help from the oil industry, are already doing so.
Science vs Art: HIV/AIDS Information, Education and Communication (IEC) Programs. What Do we Know About Program Effectiveness in an International Setting?
Authors: Krieger Gary R. , Balge Marci Z.
Published: December 2007

The actual effectiveness of Information, Education and Communication (IEC) programs for HIV/AIDS has been the source of substantial controversy. Since there is tremendous internally generated drive for companies to act as "good corporate citizens," the desire to mount both worker and community HIV/AIDS IEC programs is overwhelming. However, the measured effectiveness of these efforts is less certain. In the US, the Centers for Disease Control and Prevention recently published a Compendium of HIV/AIDS program effectiveness based upon an exhaustive review of the published peer reviewed literature. This review found very few US based papers with actual numerical measures of program effectiveness. Similar data for international based papers has not been published, although it is under active consideration by the CDC.
Integrated Compositional Surface-Subsurface Modeling for Rate Allocation Calculations
Authors: Lobato-Barradas Gerardo , Dutta-Roy K. , Moreno-Rosas Agustin , Ozgen Cetin , Firincioglu Tuba
Published: December 2007

An integrated fully compositional model describing the reservoir, wellbore and surface facilities was implemented and used to allocate the oil and gas production of 72 wells from six different fields. The model was used to simulate all the operational changes occurred in the twenty-year operating life-cycle of the fields, sharing common production and separation facilities.
Decline Curve Analysis Considering Non Laminar Flow in Two Porosity Systems
Authors: Rodríguez-Román J. , Camacho-Velázquez R.
Published: December 2007

Most of the theoretical work on decline curve analysis with non-laminar flow in the reservoir consider either a dry gas or liquid flow in an homogeneous system. The purpose of this work is to analyze decline curves considering non-Darcy flow effect in the reservoir, for a slightly compressible liquid flow in dual-porosity systems at constant wellbore pressure.

The transient and boundary-dominated flow periods are examined by means of computer results generated with a finite differences simulator. Analytical expressions of velocity and wellbore rate are presented for the first time in this paper. These equations contain the laminar flow solution as a particular case. A method is proposed to identify the presence of inertial effects by plotting d(log(q))/d(log(t)) against log (t).

The method for area calculation under laminar conditions produces a good approximation for a reservoir under non- laminar flow. However, the presence of inertial effects distort the shape of decline curves resulting in erroneus estimates of wellbore and reservoir parameters by type curve analysis with laminar decline curves.

The utility of the methodology presented in this work is illustrated with synthetic examples.
Hole Quality: Why it Matters
Authors: Chen David C-K. , Gaynor Tom , Comeaux Blaine
Published: December 2007

Hole quality is generally related to the "smoothness" of the wellbore or, sometimes, to wellbore stability. This paper will demonstrate that wellbore spiraling is the primary contributor to poor hole quality and that almost every well contains some degree of spiraling unless specific actions are taken to prevent it. Hole spiraling was first studied by Lubinski et al. in the 1950's, and they described it as a "crooked hole." Although the symptoms have been well recognized in the industry, only recently has a solution been proposed and tried specifically to cure hole spiraling. To implement the concept, two new drilling systems (a steerable motor and a rotary steerable) have been developed. Field data indicate that generating a straighter, high-quality wellbore has improved almost every aspect of drilling. These improvements include lower vibration, better bit life, fewer tool failures, faster drilling, better hole cleaning, lower torque and drag, better logging tool response, and better casing and cement jobs. Several case studies will be discussed to demonstrate the positive economic impact of producing a high-quality wellbore.
Comparison of Reservoir Properties and Development History: Spraberry Trend Field, West Texas and Chicontepec Field, Mexico
Authors: Cheatwood Chris J. , Guzman Alfredo E.
Published: December 2007

The Spraberry and Chicontepec fields are both giant oil fields contained within areally extensive, low porosity and low permeability submarine fan reservoirs. Each field has a gross interval of approximately 1,000-1,500 feet (300-450 m) with multiple reservoirs less than 10,000 feet (3,000 m) deep. Sand-prone intervals are laterally extensive and can be correlated regionally, but do have localized channeling. Both fields produce from solution-gas drive.

The Spraberry Trend Field, located in the Midland Basin of West Texas, was discovered in 1948. The field is estimated to contain over 10 billion barrels of original oil in place in a series of stacked Permian-age reservoirs covering over 2,500 square miles (6,475 sq. km). Cumulative production from the Spraberry is approximately 850 million barrels of oil and 3 trillion cubic feet of gas or approximately 8% of the original oil in place.

The Chicontepec Field, located in the Sierra Madre Oriental foothills in east-central Mexico, was first drilled in 1931. The field is estimated to contain 140 billion barrels of original oil in place and 35 trillion cubic feet of associated gas in a series of stacked Late Paleocene to Eocene-age reservoirs covering approximately 1,440 square miles (3,731 sq. km). Cumulative production from the Chicontepec Field is just over 140 million barrels of oil-equivalent or 0.1% of the original hydrocarbons in place.

However, the fields do differ significantly in their development history. Over 18,000 wells have produced some oil and gas from the Spraberry (over 10,000 currently producing) as compared to less than 1,000 in Chicontepec. Managing drilling costs, fracturing technology and controlling production costs along with economies of scale have allowed the Spraberry, once known as the world's largest uneconomic field, to be developed. Developing the Chicontepec field using similar methods would add significant reserves and production volumes for Mexico.
The Introduction of New-Generation Positive Displacement Motor Technology in Combination with Application-Specific PDC Bits: A Step Improvement in Drilling Performance on Horizontal Rotliegendes Sandstone Sections
Authors: Grindrod J. , Rayton C. , Sim C. , Biggs N. , Brown A. , Tayler P.
Published: December 2007

Wells on the Jupiter field, UK Southern North Sea, require relatively long (1,000 – 5,372 ft) horizontal 6" hole sections to be drilled through the Permian age, Rotliegendes sandstone reservoir. Tight target tolerances on true vertical depth necessitate good directional control over the entire section length. Historically, the following technology combinations were utilised to drill these sections; high-speed turbines run in conjunction with polycrystalline diamond compact (PDC) drill bits or diamond impregnated bits; conventional low speed Positive Displacement Motors (PDMs) coupled with both roller cone bits and PDC bits.

Drilling with turbines resulted in heavy drill bit wear due to high rotational speeds and required significant periods of orientation to combat the inherent left hand walk tendencies of the assemblies. Conventional PDM and roller cone assemblies gave rise to multiple trips due to bit bearing life limitations on run length. The problems of erratic PDC bit torque and stalling of conventional motors due to variable weight transfer coupled with motor torque output limitations, made attempts to use this combination unsuccessful.

The development of a new generation PDM that was able to produce significantly more power and torque than conventional motors, at comparable bit speeds, was introduced to overcome these problems. Compared with turbines the new generation Extra Power Motor, (XPM), was found to be easier to control, monitor and optimise, as both revolutions per minute (RPM) and power output are directly proportional to drilling fluid flow rate and motor differential pressure respectively.

In conjunction with the new XPM technology, application specific PDC bits featuring a unique tandem gauge were designed to maximise hole quality and therefore provide more even weight transfer to the bit. This combined with an optimised PDC cutting structure facilitated smooth torque output at the bit-rock interface and so supported the use of the new motor technology.

This paper uses case histories to describe how the application of this new technology on three wells led to a step improvement in performance when compared to conventional drilling methods. Gross section rate of penetration (ROP) was improved by up to 300%, and the operator achieved the longest horizontal section to date through the Rotliegendes. Future developments to meet ongoing challenges and realise the full potential of this technology are also presented.
Case History of First Use of Extended-Range EM MWD in Offshore, Underbalanced Drilling
Authors: Weisbeck D. , Blackwell G. , Park D. , Cheatham C.
Published: December 2007

This paper discusses the planning, results, problems, and lessons learned during the first use of the Extended-Range Electromagnetic (EM) MWD system for underbalanced drilling in an offshore well. The use of EM MWD in offshore applications has historically been limited due primarily to the difficulty of seabed deployment of the receiving antenna. In underbalanced drilling, however, EM is the MWD system of choice because mud-pulse telemetry has great difficulty operating in two-phase flow conditions commonly used. If underbalanced drilling is to become more frequently used offshore, then one limitation that must be overcome is the difficulty for MWD systems to provide real-time annular pressure, directional, and formation evaluation information.

Repsol-YPF-Maxus successfully used underbalanced drilling on Krisna Well D12 in offshore Indonesia to prevent massive lost circulation and stuck pipe in the reservoir. Although the total vertical depth of the well was relatively shallow (approximately 4,200 ft subsea), the very low resistivity of the formations above the reservoir precluded use of standard EM MWD services. The Extended-Range EM MWD system was used to extend the depth capability.
Drilling the HP/HT Moon Prospect Exploration Well
Authors: Ghosh Kallole , Wali Vinod K. , Bansal Sanjeev , Jaggi Anil , Oglesby Darrell W.
Published: December 2007

Planning for the deep vertical exploration well, in shallow waters off the West Coast of India commenced more than a year ahead of drilling operations. The well was targeted to 4500m to explore deep objectives in a four-way closure. Bottom hole pressure was expected to be in excess of 12000 psi and formation temperatures were predicted to be higher than 400°F (205°C). A major challenge was mobilizing special high pressure equipment to an area with limited oilfield infrastructure. The successful drilling and formation evaluation of the well has validated the efficacy of the design philosophy, highlighted the critical importance of mud hydraulics, HP/HT rheology, temperature modeling, real time detection of pressure transition zones, and will significantly impact future exploratory drilling operations in the area.
Surface BOP - Management System & Design Guidelines
Authors: Azancot P. , Magne E. , Zhang J.
Published: December 2007

This paper presents an overview of the comprehensive Management System & Design Guidelines created to safely implement Surface BOPs in variety of environments. In particular, the Management System enables the use of the Surface BOP in environments other than the benign met ocean/formation conditions where these systems have been deployed to date.

The components of this Management System are: Introduction, Background and Philosophy; Performance Standards; Performance Assurance Process; Equipment Specifications and Verification; Performance Assurance Objectives; Surface BOP Design Guidelines & Governing Standards, Risk Management, Operating Procedures and Maintenance / Inspection Procedures

The paper concludes that use of such a comprehensive Management System enables the Surface BOP (SBOP) to be deployed in many environments.

SBOP technology significantly reduces the deck loading for rigs when compared to using conventional marine risers in deepwater and enables the use of smaller rigs in deepwater. The potential cost savings are large.
High Performance Coil Tubing Drilling in Shallow North Slope Heavy Oil
Authors: Rixse Mel , Johnson Mark O.
Published: December 2007

Coil tubing drilling (CTD) completed a very successful 4 well pilot project that drilled lengthy horizontal multi-laterals into shallow heavy oil reserves at the Milne Point field on Alaska's North Slope. The CTD sidetracks were drilled with the proper combination of tools that delivered good incremental oil production rate at low cost.

This was a new field for the CTD team with challenging directional and completion issues. A coiled tubing electric line drilling BHA and innovative completion techniques were required to achieve objectives. Three dual-lateral wells and one single-lateral well were drilled into thin shallow sands and completed using slotted liner and flow-through whipstocks.

Sensors in the modular electric-line CTD bottom-hole-assembly communicated to the surface with an electric line umbilical that provided extremely high-speed directional information, real time downhole weight on bit (DWOB), resistivity data, gamma-ray data, internal pressure and annular pressure data. The electric line also provided power to accurately drive a downhole electric orienter. These features combined with high performance PDM motors achieved very high penetration rates with 3.75 inch PDC bits. Several North Slope CTD drilling records were set during the project.

Liner running from high departure parent wellbores proved to be quite challenging but ultimately successful. Learning and performance improvements were made as the project progressed. This paper will review the performance of the CTD BHAs and the completion innovations applied in this project.
The Effect of Drilling Fluid Rheological Properties on Hole Cleaning
Authors: Saasen A. , Løklingholm G.
Published: December 2007

Hole cleaning is still among the most important problems to handle in drilling operations. The difficulty in removing cuttings bed during drilling arises because of the drilling fluid interacts with the cuttings in cuttings bed to form a cuttings bed gel. The drilling fluid composition can be designed to minimize the gel formation in the cuttings bed. At the same time the drilling fluid properties are optimized to ensure a sufficient shear stress on the cuttings particles to be able to remove the cuttings. This technique has been used in several of Statoil's drilling operations.

The paper explains the effect of the cuttings bed properties on hole cleaning in detail. Furthermore, the paper demonstrates how the drilling operations were improved compared to earlier drilling operations using conventional drilling fluids. From drilling operations in North Sea fields it is shown how the total drilling progress is improved. The torque curves of comparable wells are shown. These curves demonstrate that a significantly improved hole cleaning have been experienced in the wells drilled with the drilling fluid made to minimize cuttings bed gel formation.
Web-Based Occupational Health, Safety and Environmental (OHSE) Management Tools: Can They Help Companies Manage OHSE Performance in a Cost-Effective Manner?
Authors: Shaw R. D. , Livingston R. D.
Published: December 2007

Management of information is a major challenge facing corporations operating in today's regulated environment. Information relevant to corporate OHSE performance arises from various sources, e.g., OHSE laws and regulations, corporate monitoring programs, and corporate management systems to name a few. Further, the requirement for managing this information is continually growing, e.g., changes in OHSE laws and regulations, collection and analysis of new monitoring data, changes in corporate OHSE programs, increasing concerns related to litigation, and increasing scrutiny of OHSE performance by the public. Many companies, particularly those operating internationally, are seeking ways to effectively deal with this information.

There are various tools available for a corporation to manage this information. Many companies have over the years developed their own in-house databases, which are maintained internally and provide a reasonable approach for managing certain types of data. Unfortunately, many of these databases rely on the expertise of one or a few key individuals, and when those individuals depart the database is generally not maintained or modified to account for the changing needs of the company. Few companies have any formal approach for ensuring that they are compliant with all relevant legislation and regulations.

The Internet has led to the development of a wide range of OHSE management tools. The various products that are available all suggest that they are a panacea for solving corporate OHSE problems. In reality, many are simply web-based extensions of existing management tools and are not taking full advantage of the opportunities that the web can provide. For instance, the web allows the customization of management tools that are easy to use yet incorporate sophisticated intelligence or analysis that links back to databases in various locations. We will describe examples of such web-based tools and how they can aid in effective OHSE management.
Latest Technology Equidistant Power Section Increases Overall Performance of a Workover Motor
Authors: Hazenberg Frans , Regener Thorsten
Published: December 2007

A new workover motor, incorporating equidistant power section technology, has demonstrated that it can produce more torque for milling/workover operations and can operate at higher temperatures than previous positive displacement motor (PDM) designs. This paper discusses the operating principles of PDM tools to show how the equidistant technology increases efficiency and improves performance. In addition, the paper presents laboratory and operational test examples that verify the performance improvements. Three case histories demonstrate how this technology has reduced the cost of well intervention through higher Rates of Penetration, reduced milling times, fewer trips to surface and increased equipment reliability.

The new technology incorporates a unique and innovative "equidistant" power section design. The power section is made with a proprietary, contoured stator manufacturing process that reduces the motor’s rubber content considerably for higher efficiency, lower friction and less distortion. The case histories presented here discuss applications that previously would have been considered too risky or impractical for standard PDM motors. The case histories also substantiate that this power section technology is more tolerant when exposed to higher temperatures, pressures and fluid solids.
Use of a Crosslinked Polymer Fluid-Loss Control Agent to Aid Well Cleanouts
Authors: Rosato M. J. , Supriyono A.
Published: December 2007

Low-permeability gas sands are often cased, perforated, and hydraulically fractured in stages. Commingled production is common, and coiled tubing (CT) has become the medium of choice for opening multiple productive intervals between fracture stages and for use as a remedial workover method.

High differential pressures in the wellbore complicate CT intervention considerably. Bridging agents are sometimes used to combat severe lost circulation and associated well control problems. Calcium carbonate may be the most common bridging agent because it is inexpensive and easy to mix; however, removing the damage caused by calcium carbonate slurries to the formation and proppant packs is difficult and costly. Salt pills are widely used because they cause less formation damage, but they are ineffective at controlling severe fluid loss. Furthermore, to prevent dissolution of the pill, saturated brine must be used as a workover fluid, increasing costs and contributing to scaling problems.

A unique fluid-loss control agent has been gaining popularity for temporarily isolating low-pressure, fractured sands. This double-derivatized, crosslinkable, hydroxyethyl cellulose (DDHEC) polymer leaves less than 0.5% gel residue by weight, minimizing impact on production. It has demonstrated a regained permeability of 91 to 93% under laboratory conditions and can be completely removed by acid. The polymer has been used in conjunction with 1.25- and 1.75-in. CT with a high degree of success. It does not require expensive brines, is resistant to solvents, and can be used with foam.1,2

Eight field applications of the polymer have been performed, none of which have negatively affected production. This paper provides case histories for several of these field applications and defines techniques and selection criteria for applying the polymer under specific well conditions.
Single Well Chemical Tracer Test to Determine ASP Injection Efficiency at Lagomar VLA-6/9/21 Area, C4 Member, Lake Maracaibo, Venezuela
Authors: Hernández Clara , Chacón Larry , Anselmi Lorenzo , Angulo Reinaldo , Manrique Eduardo , Romero Eucario , de Audemard Nancy , Carlisle Charles
Published: December 2007

Single well chemical tracer tests (SWCT) were carried out at the VLA-1325 well located in Lagomar, C4 reservoir, Lake Maracaibo, Venezuela, to measure residual oil saturation in zone C4-U3 before and after an ASP injection, in order to determine the swept efficiency of a custom made blend. The tests included: Phase I, measurement of residual oil saturation to water (SorW) of the pay zone, previous to an ASP application and after waterflooding procedure; Phase II, application of an ASP blend, specially designed for the aforementioned zone; and Phase III, second measurement of residual oil saturation to ASP (SorASP) after ASP application.

The results show that prior to the ASP injection, the residual oil saturation at the VLA-1325 was (31 ± 3)%. This saturation measurement represents pore space in a 6.7 m (22 ft) thickness portion (1,842.4 - 1,849.1 m; 6,048 - 6,070 ft) of the C4-U3 zone from the well bore to a radial position of about 3.04 m (10 ft). A few days after this initial residual saturation, measurement was completed. A 0.35 porous volume, Vp, (1,750 bbl) ASP injection was carried out in the same 6.7 m (22 ft) completion of the C4-U3 zone. This ASP mixture was followed by 0.15 Vp (750 bbl) polymer drive solution, and a 1.2 Vp (6,000 bbl) of fresh water to push the ASP mixture and any mobilized oil about 15.8 m (52 ft) away from the test well-bore. After ASP treatment, the residual oil saturation measurement was repeated in the same pore space as the initial SWCT test investigated. This post-ASP flood SWCT test showed that the residual oil saturation in this pore space had been reduced to (16±3)%. This reduction in the SorW represents (48±1)% mobilized oil by the chemical treatment. The reported Sor measurements represent the average Sor s for the sub-zones penetrated by the tracer fluids during the test. The field data recorded during the test are presented, and compared with best-fitting simulation model results.
Reservoir Mechanism for Hunton Formation Production
Authors: Marwah Vineet , Kelkar Mohan , Keefer Brian
Published: December 2007

Hunton Formation is one of the most promising formations producing oil and gas in Oklahoma. The formation has an anomalous producing behavior. At the inception, the wells produce at relatively high water –oil and gas-oil ratios. Eventually, both the WOR and GOR decrease. This results in an increase in oil cut and hence reduction in lifting costs over time. Because of relatively high WOR's, many operators are discouraged from completing the wells, and hence abandoning the effort to produce oil from these formations.

This particular behavior has been addressed with different names: de-watering, reverse coning, to name a few. We call this behavior ROC (retrograde oil cut) mechanism. Our goal is to explain various anomalous behaviors in the field production, which can be reproduced by geologically defensible reservoir model. We tested several models by comparing the field data with the simulated behavior. Finally, we converged on to a three-layer model – which is geologically and core data consistent – and can produce various anomalous characteristics. These include decrease in WOR over time, increase in GOR after the well has been shut-in, long transient state behavior of oil production, and the decline in pressure (instead of pressure build-up) after some of the wells have been shut-in for 24 hour periods. We have integrated available core and log data, relative permeability data, geological understanding as well as PVT data to build this model. We tested this model by mimicking production from several wells in West Carney Field in Oklahoma.

The implications of understanding the mechanism are enormous. Although we only concentrated on Hunton Formation in one county, Hunton formation extends over 2 million acres in Oklahoma alone. Similar formations also exist in other states, which were deemed unproductive in the past. By correctly understanding the production mechanism, the viability of producing from other similar formations can be better investigated.
A Study of Steam-Assisted Gravity Drainage Performance in the Presence of Noncondensable Gases
Authors: Canbolat Serhat , Serhat Akin , Kovscek Anthony R.
Published: December 2007

Traditionally, the addition of a non-condensable gas to steam is known to have a beneficial effect on heavy-oil production when conventional vertical wells are used. Little information and experimental evidence exists regarding the effect of the addition of such gases in the steam assisted gravity drainage (SAGD) process. The limited literature suggests that the addition of small amounts of such gases (e.g., carbon dioxide) may improve oil recovery. The gas accumulates at the top of the reservoir and provides a thermal and pressure insulation effect that in turn limits the rate of front spreading at the corners of the steam chamber.

In order to investigate these phenomena, SAGD experiments with and without carbon dioxide injection were conducted in a physical model. It is packed with crushed limestone premixed with a 12.4° API heavy-oil. Temperature, pressure and production data as well as the asphaltene content of the produced oil were monitored continuously during the experiments. It was observed that for small well separations as the amount of carbon dioxide increased, the steam condensation temperature and the steam-oil ratio decreased. The heavy oil became less mobile in the steam chamber due to lower temperatures. Thus, the heating period was prolonged and the cumulative oil recovery as well as the recovery rate decreased. In this instance, the produced oil contained a relatively high concentration of asphaltenes. This supports the observation of poorer oil recovery as the fraction of carbon dioxide injected increased. A large asphaltene fraction in mobile oil serves to maintain high viscosity. On the other hand little or no change in oil recovery and oil recovery rate was observed for larger well separations regardless of the fraction of carbon dioxide in the injection gas. Similar behavior was observed when n-butane was injected along with steam instead of carbon dioxide. The impact of initial gas saturation (carbon dioxide or n-butane) was also investigated. It was observed that cumulative oil recovery, rate of oil recovery, and steam-oil ratio decreased independent of well separation compared to a reservoir with no initial non-condensable gas.
Fluid Flow Control Using Magnetorheological Fluids
Authors: Zitha P. L. J. , Wessel F.
Published: December 2007

Magnetorheological fluids (MRFs), i.e. suspensions of ferri- or ferromagnetic particles in a water or an oil-based carrier fluid, stabilized by a surfactant or polymer, are deemed suitable for fluid flow control in oil and gas recovery operations. This paper reports a laboratory study on the rheology of oil-based MRF and its influence on oil and water flow in cores. Two types of experiments will be discussed: (a) flow of an MRF in a tube and (b) flow of oil or brine in sand-packs previously saturated with a MRF. In both types of experiments, the flow rate and the strength of the magnetic field were varied.

Tube flow experiments show that MRFs can be characterized by yield point and, above the yield point, by a shear-thinning behavior. In the presence of a magnetic field the rheological parameters change drastically leading to a gel type of behavior. On one hand, the yield point and the plastic viscosity increase strongly and, on the other hand, the power law exponent decreases and then levels off to a plateau. We propose a simple rheological model conveying these features.

On the core side, residual resistance factors (FRR) in the order of a few thousand were obtained under moderate magnetic fields. For a fixed magnetic field, the FRR for oil is lower that that for water by at least an order of magnitude. The data suggest that magnetorheological fluids are efficient flow control systems that could be used to maintain pressure in the well at a certain level (e.g., to prevent a "blowout"or leakoff during drilling), to reduce circulation loss or to reduce water production in hydrocarbon wells.
Hydraulic Fracturing Improves Recovery in a Layered Reservoir Under Waterflood in Kazakhstan
Authors: Shaoul Josef , Folmar Edgar , van Gijtenbeek Klaas
Published: December 2007

This paper presents a case study of a successful hydraulic fracturing campaign in the Arman field in western Kazakhstan: the first large scale campaign ever performed by a western service company in Kazakhstan. The Arman field is a mature field, originally delineated in Soviet times, and currently producing from four of the original vertical wells, and from newly drilled deviated (30 to 60 degree) wells. The field is currently under waterflood in three of the producing zones, but formation water is also being produced from wet zones. There is significant gas production, since the wells are all producing below the bubble point, either with ESP's or rod pumps.

We believed that hydraulic fracturing had good potential for stimulation in this field since most of the wells were producing with a positive skin. In addition to the positive skin, the reservoir was normally pressured, and also depleted in some zones, limiting the amount of drawdown to about 1000 psi. The wells were also producing water and gas in addition to oil, which further reduced the oil production (by a variety of mechanisms).

In this paper, we first describe the hydraulic fracturing operations, and the specific actions taken to deal with difficult features of this reservoir. We then examine the production mechanisms in the reservoir and compare the pre and post-fracture production data. Finally, we evaluate the effectiveness of hydraulic fracture stimulation as a method for improving oil recovery in this type of moderate permeability reservoir under waterflood.
Some Aspects of 4-D Seismics for Reservoir Monitoring
Authors: Marschall Roland , Sherlock Donald
Published: December 2007

This contribution demonstrates how the seismic technique can be a valuable tool to improve the accuracy of simulation predictions and optimize the efficiency of hydrocarbon production. We illustrate how time-lapse 3D (or 4D) seismic can be used to monitor the movement of oil-water contacts and map changes in saturation throughout a reservoir over discrete intervals in time.

Quantitative data can be extracted from the monitoring quantity, i.e. either seismic amplitude data or acoustic impedance data, depending on whether the flow regime being considered is segregated or diffusive. For segregated flow conditions, 4D seismic can be used to monitor the movement of the oil-water contact (OWC) in time and space. It can also clearly identify undrained compartments of a producing reservoir and be a valuable guide for planning new wells. Potential problems such as coning can be ‘seen’ prior to water breakthrough and be prevented by controlling production and injection rates. For diffusive flow, where there is no explicit OWC, acoustic impedances can be used to map changes in saturation and evaluate areal sweep efficiency.

Two examples are discussed to illustrate 4D seismic monitoring of segregated and diffusive flow respectively. The first example is from a sandstone reservoir at 1600m depth in the North Sea, with porosity of 27% and permeability of 4 Darcy. The second example is of an inverted 5-spot water flood pilot project, where 4D seismic was used over a time span of 6 months for a 90m thick carbonate reservoir at 2000m depth, with porosity of 21% and permeability of 31mD. We will also show results of two physical fluid-flow models where air and kerosene were injected and monitored with 4D acoustics under controlled conditions. These results serve as an impressive demonstration of the ultimate resolving power of the seismic technique in measuring actual flow in a reservoir.