bluuebunny/crossref_metadata_2025 huggingface dataset:
Feasibility Study of In-situ Combustion in a Carbonate Reservoirs
Authors: Mostafavi S. Vahidreza , Kharrat R. , Razzaghi S.
Published: December 2007

Heavy oil recovery studies is now being carried out in Iran since there is remarkable amount of heavy oil bearing formations in this country.

KMO oil field is one of the most important oil fields in which the different recovery methods are being investigated. However, due to very high viscosity the in-situ combustion process seems to be feasible. This field contains heavy oil with very low API degree, near eight, in Sarvak and Asmari formations.

To investigate the feasibility of this process, in-situ combustion tube tests on KMO rock and oil have been carried out. Through these experiments combustion front temperature was about 500° C. Additionally combustion front velocity and recovery has been measured. The amounts of oxygen, carbon monoxide and carbon dioxide have been measured by analyzing the effluent gas.

One of the risks of running combustion process in carbonate formations is the probability of decomposition due to very high temperature. While decomposition occurs in dolomite or lime stone, the rock will change in to a powder like material that will definitely cause plugging. The carried out tests along with TGA/DSC tests done show that there is no risk of decomposition in KMO reservoir rock around the temperature attained in the combustion front.

Finally, the results of the experiments were simulated to predict and investigate the effect of fractures contribution to the process.
Effects of RPM and ROP on PDC Bit Steerability
Authors: Ernst Stephen , Pastusek Paul , Lutes Paul
Published: December 2007

Directional drilling is a critical necessity in many of today's wells. Accurate prediction and awareness of achievable build rates is vital in lowering drilling cost. The science behind controlled wellbore deviation has advanced beyond prediction based solely on BHA geometry. Although BHA configuration is an important factor, interaction between each of the four primary components (bit, BHA, operating parameters and formation) must be evaluated thoroughly.

Previous papers have described how changes in bit characteristics, BHA configuration and various formations influence build rates. With regards to operating parameters, weight-on-bit (WOB) is well-known to be beneficial in increasing the desired build rate under certain drilling conditions and yet does not help in other situations.

We propose that most of the weight-on-bit effects are actually due to its influence on rate of penetration and bit tilt. However, the influence of operating parameters has not been fully investigated. RPM has been neglected as a significant influence on steerability. In theoretical studies, these properties have been measured and quantified with the use of a full scale drilling laboratory and commercially available PDC bits. This paper investigates the effects of RPM and ROP on build rate and illustrates the importance of these parameters. Practical guidelines for understanding the effect of operating parameters on steerable systems are also provided.
Demonstrating Managed-Pressure Drilling With the ECD Reduction Tool
Authors: Bansal R. K. , Brunnert D. , Todd R. , Bern P. A. , Baker R. V. , Richard C.
Published: December 2007

The equivalent circulation density reduction tool (ECDRT) is designed to counter the increased fluid pressure in the annulus caused by friction loss and cuttings load by reducing the total hydrostatic head. The tool has a broad range of drilling applications, including: narrow pore/fracture pressure margins in deep water and their effects on casing setting-depth selection; wellbore instability; depleted reservoirs; and extended-reach wells.

This paper describes progress on development and testing of a prototype ECDRT. The prototype was recently tested in a BP onshore U.S. Arkoma asset operation in southeastern Oklahoma. The primary objectives of the field trial were: 1) determine ECD reduction performance; 2) establish reliability in field conditions; and 3) evaluate the ECDRT operational procedures. The test involved drilling 8.75-in. hole with the tool running inside 9.625-in. casing cemented at a depth of 4,500 ft. Performance was monitored continuously from a real-time display of surface and downhole measurements.

Wellbore pressure management was clearly demonstrated in the field trial. The ECDRT consistently reduced ECD by about 150 psi, or the equivalent of about 0.7 ppg at 4,500 ft. Drilling performance was not limited in any way by the ECDRT. Fluid returns and wellbore cleaning were normal throughout the drilling operation. The ECDRT processed cuttings generated by the drilling at 100 ft/hr without difficulty. More than 500 ft of hole was successfully drilled before the tool was pulled because of difficulties with the directional drilling system. The final goal to evaluate ECDRT operational procedures was achieved as performance indicators on the surface worked reliably to diagnose the operational status of the tool.

Post-well analysis showed that there were still some design issues to secure the longevity and sustained performance of the tool. The tool demonstrated the ability to manage annular pressure under actual drilling conditions.
Nuclear Magnetic Resonance Logging: While Drilling, Wireline, and Fluid Sampling
Authors: Seifert Douglas J. , Akkurt Ridvan , Al-Dossary Saleh , Shokeir Ramez , Ersoz Haluk
Published: December 2007

Over the past decade, results from Nuclear Magnetic Resonance (NMR), logs have added significant value to petrophysical analysis by providing total, free-fluid and bound-fluid porosities. The development of Nuclear Magnetic Resonance tools for the LWD environment allows this valuable information to become available during the drilling operation, before significant invasion, allowing timely decisions, as well as reduced borehole risk.

Data from a Nuclear Magnetic Resonance Logging While Drilling tool (MRIL-WD) was acquired in a recently drilled well in Saudi Arabia. This well was extensively cored and logged. In addition to LWD NMR, wireline NMR logs (MRIL-Prime), and NMR fluid analyzers (MRILab) were also run.

This paper, following a brief discussion on the operation of MRIL-WD tool, compares and contrasts the results between while-drilling and wireline NMR logs. NMR fluid properties obtained from the NMR Fluid Analyzer are also crosschecked with the log data.

Obtaining Nuclear Magnetic Resonance data earlier in the drilling process will allow NMR logging to become one of the backbones of formation evaluation.
A Systematic Approach to Remove Iron Sulphide Scale: A Case History
Authors: Leal Jairo , Solares J. Ricardo , Nasr-El-Din H. A. , Franco Carlos , Garzon Francisco , Marri Hamad M. , Aqeel S. A. , Izquierdo Guillermo
Published: December 2007

A number of Khuff reservoir gas condensate wells have been on production for more than twenty years in Saudi Arabia. Many of these wells are classified as sour gas producers with hydrogen sulfide levels upwards of 10 mol% and carbon dioxide of 4-5 mol%. Most wells are completed with C-95 tubulars to withstand high stimulation treatment pressures. Condensed or formation water production rates range from 2 to 100 BWPD. The condensate to gas yield ranges from 30 to 250 BBLS/MMSCFD depending on the area of the field. Recent extensive lab work indicated that the iron sulfide scale deposits observed in the production tubulars of a number of wells comprised various types of iron sulfide, iron carbonate and calcium carbonate compounds.

Removing iron sulphide scale is a complex process, especially at downhole temperature and pressure conditions (285°F and up to 7,000 psi. in Khuff gas producers). Inorganic acids cannot dissolve all types of iron sulphide scale. As iron sulphide scale (FeS) ages, it is converted into pyrite (FeS2) which is insoluble in mineral acids. Moreover, iron sulphide is oil-wet, a condition which creates a protective organic coating that minimizes contact with acids and chelating agents. Furthermore, the hydrogen sulphide released during the acid dissolution of acid-soluble scale may cause serious problems, because the spent acid may redeposit iron sulphide and elemental sulphur.

This paper describes a systematic approach pursued to identify the optimum methodology to effectively remove complex iron sulphide scale in Khuff reservoir gas producers ahead of field trials. A discussion on iron sulphide scale dissolvers and an optimized mechanical scale removal using fluidic oscillation technology is included. Details of a significant number of dissolution tests conducted are shared.
Encountering an Unexpected Tar Formation in a Deepwater Gulf of Mexico Exploration Well
Authors: Weatherl M. H.
Published: December 2007

Industry experience reveals that tar formations can present significant challenges in deep water drilling operations (1-4). In a case where several feet of active tar is present at depth, substantial trouble time often results. Tar can even prevent reaching programmed depth in some cases. These difficulties are further compounded in a high cost environment with limited rig availability where project appraisal and viability can be impacted (5).

These events came to pass for Chevron and partners during late 2005 and early 2006 on the ‘Big Foot’ Prospect in the Gulf of Mexico at Walker Ridge Block 29 (see Fig. 1 Walker Ridge Area). Challenges on this sub salt prospect included loop currents, an active hurricane season, and numerous subsurface issues related to geologic uncertainty, narrow pore pressure/fracture gradient margins, and wellbore stability.

This paper will focus primarily on issues related to the tar formation which was encountered below salt, its impact on operational strategy, lessons learned, and steps taken to ultimately achieve the well objectives.
Premature Yielding Identified in First Comprehensive 2-million-lbm Deepwater Landing String Test Program
Authors: Bradford Dale W. , Payne Michael L. , Schultz Donald E. , Adams Burt A. , Vandervort Kurt D.
Published: December 2007

The purpose of this paper is to present the results of a comprehensive test program conducted with five different sets of deep-water landing string handling equipment consisting of both conventional and unconventional technology. A thorough presentation will be made detailing initial testing at elastic loads approaching yield and final high load testing beyond yield. All stages of the test program will be discussed including original testing protocol, test setup, testing performed, test results, and overall conclusions. This is one of the first standardized test programs used across five different designs of handling equipment. This overall presentation of the test program is made to identify stress levels associated with the extreme loads that occur when landing very heavy casing strings in deep-water wells.
Application of Purpose-Built Rig Technology Results in Step Change of Drilling Time, Cost, and Opportunities
Authors: Kolstad E. S. , Steinke L. D. , Brady L. S. , Marchand S. P.
Published: December 2007

The Piceance Basin, located in Western Colorado, is a 6,000-square-mile basin consisting of vertically stacked sand-shale sequences. Gas-in-place estimates exceed 200 trillion cubic feet. The operator started developing its acreage in 1982 with 160-acre bottom-hole spacing. Over time, dictated by reservoir performance and enabled by drilling and completion technology, such as PDC bits and directional drilling, field development migrated to 10-acre bottom-hole spacing with surface locations consisting of three to four wells per pad. Historically, pricing pressures dictated the use of conventional mechanical drilling rigs. In recent years, as product prices increased and as well inventory in easily accessible areas became drilled up, the need to drill many wells from a single remote surface location became apparent. These purpose-built rigs facilitate this, plus bring multiple performance improvements, environmental benefits, and well cost reduction to the asset. This paper will be presented by E.S. Kolstad at the 2007 SPE/IADC Drilling Conference held in Amsterdam, The Netherlands, 20-22 February 2007.
CIDS to Orlan: Transformation and Startup of Sakhalin's Ice-Resistant Drilling Platform
Authors: Higgins Anthony M. , Zuskov Boris , Zande Paul Vande
Published: December 2007

The drilling and operating environment offshore Sakhalin Island is one of the most challenging in the world. The combination of extreme weather, ice-pack conditions, remote location, and world-class, three-dimensional (3D) extended reach drilling (ERD) objectives demands a highly specialized drilling and production installation to realize success. The milestones and learnings attained during the conversion and start-up of the former Glomar Beaufort Sea I (CIDS: Concrete Island Drilling Structure) to its current status as the Orlan Drilling and Production platform are detailed in this paper.

Starting with the platform redesign and transformation through the commencement of drilling operations, the project has successfully met and overcome multiple challenges. The original CIDS facility, built in the 1980's, was designed to drill a maximum of three arctic exploration / appraisal wells. The basic structure and platform modules were upgraded to provide the full complement of fifth generation drilling elements needed to support a remote, offshore operation in the seismically active, Russian arctic environment. The Orlan platform is now capable of continuous operations throughout the harsh storm and ice-pack conditions of offshore Sakhalin Island. The drilling systems enable efficient completion of world-class, 3D ERD-length wells and the production facilities will allow for year-round oil and gas delivery. The upgrade yielded substantial savings over the design and construction of a new gravity-based structure (GBS) and fifth generation rig.

Drilling operations on the Orlan platform began at the start of the 2005 winter and ice season. Marine and aviation logistics support functions were stretched to their working limits in order to sustain continuous operations. The highly-competitive local labor market and difficult travel conditions impacted personnel continuity. Extreme weather conditions affected the offshore working environment and heating systems.

Despite the challenges, the upgrades were completed safely, the platform was delivered in a timely fashion, and optimizations continue to be realized. The successful conversion and start-up of the Orlan drilling and production platform illustrates the unwavering focus the Company places on safety, flawless execution and timely application and deployment of technology and personnel.
Semiphenomenological Model of Hydraulic Fracturing in Granular Media
Authors: Alekseenko Olga
Published: December 2007

Petroleum engineers have faced the problem of hydraulic fracturing in soft rock formations for many years. However, existing programs used with soft rock formations often do not provide satisfactory treatment designs. Difficulties emerge because hydraulic fracturing in soft rock involves development of a plastic zone near the fracture surface, where rocks partly lose their cohesion. This study has developed a more appropriate model for fracture design, which takes into account processes in the plastic zone for the special case of soft rock that is a cohesionless granular impermeable medium.

The real problem of hydraulic fracturing in an elastoplastic medium has been represented in the model as brittle hydraulic fracture growth in a quasielastic medium. The medium resistance to fracture development is determined by variable apparent fracture toughness, which is a function of the fracture length and is found from the analysis of energy dissipation in the plastic zone.

The dependence of the apparent fracture toughness on input parameters and fracture width at the fracturing fluid front has been established. It reflects the specific feature of the granular medium deforming and closes the equation set of the problem. Semianalytic solutions are obtained. First, there is the area of input parameters, where the effect of plasticity on fracture geometry is significant. Secondly, fracture behavior depends on the typical magnitude of friction forces on fracture sides, but it depends also on the fracturing fluid rheology.

This new model of hydraulic fracturing in a granular medium is an improvement over existing models because traditional brittle fracture models do not take into account the specific rheology of soft rocks and poorly predict fracture geometry. Newer elastoplastic models are unclosed because the size of the plastic zone is undefined. Also, they usually are finite element models and cannot be used for the calculation of practical fracture designs because of time limitations.

This work is only the first step toward practical hydraulic fracturing design in soft rock formations. The model is supposed to be developed and validated against experimental results or field data.
Development of a Subsea TTRD Capability West of Shetland
Authors: Johansen Robert , MacLeod Angus
Published: December 2007

This paper describes BP's project to develop a subsea Through Tubing Rotary Drilling (TTRD) capability in its Deep Water Performance Unit (DPU) West of Shetland.

Lower cost access to barrier reserves and small hydrocarbon accumulations are part of a field development strategy to increase recovery factor and maximise total recovery through the application of new technology. A key challenge of this strategy is the unique application of through tubing rotary drilling techniques to the subsea wells in the hostile deep water West of Shetland.

Project activities leading to implementation in 2009 / 2010 are described. It was identified that an integrated project team consisting of key stakeholders managed by BP would deliver the most robust approach to the extreme challenges of Subsea TTRD delivery. In conjunction with the subsea well environment this represents a key difference to contemporary, platform TTRD projects and supported several key activities: Front end engineering design (FEED) involving Drilling Contractor and Subsea Equipment Manufacturer.Development of a Statement of Requirements and description of riser, BOP and control systems to enable TTRD in subsea wells. Interfaces to semi-submersible mobile offshore drillng unit (MODU).Modifications to rig pipe handling system, active pit system and enhancements to kick detection capability.Mitigation of fatigue damage caused by very high currents experienced West of Shetland acting on the riser and resulting in vortex induced vibration.Damage prevention techniques for Subsea Xmas tree, SCSSSV and tubing.Unique well engineering challenges relating to annulus integrity and TTRD in water injection wells.

The key conclusions from FEED are explained and their impact on equipment, techniques and procedures as applied to Subsea TTRD is described.
Reservoir Candidate Screening: The SURE Way to Successful Underbalanced Drilling Projects - Case Study
Authors: Keshka Ashraf , Al Rawahi Ali Salem , Al Murawwi Rashed Abdulla , Al Yaaqeeb Khalid , Qutob Hani , Boutalbi Said , Villatoro Jaime
Published: December 2007

Abu Dhabi National Oil Company (ADNOC) and its group of companies are considering adapting new technologies to ensure that strategic resources are optimally explored, developed and produced during the life cycle of their oil and gas fields. Underbalanced Drilling (UBD) technology, which can achieve these objectives effectively when applied in conjunction with horizontal drilling techniques, is being considered among various options.

Abu Dhabi Company for Onshore Oil Operations-ADCO, decided to pioneer the introduction of the new technology. A systematic scientific approach was applied to screen thirty reservoirs for underbalanced drilling candidacy, in order to identify the best potential candidates from a given portfolio and to ensure a successful pilot application.

The screening process incorporated reservoir, drilling, and operational data with risk analysis into a rigorous expert system aimed at maximizing the value of any UBD operation. The screening process was performed in two phases;

Phase I comprised of:

- Evaluating and ranking thirty reservoirs with respect to their risked probability of being successfully exploited with horizontal underbalanced drilling and completion techniques as opposed to conventional drilling and completion techniques.

- Comparing candidate reservoirs against global database of analogues proven to be suitable with UBD.

- Selecting the best three candidates for the Phase II detailed reservoir damage analysis and productivity forecast.

Phase II comprised of:

- Identifying the formation damage mechanisms that are expected to occur in each of the three reservoirs.

- Comparing underbalanced and overbalanced costs, production rates, projected revenues and net present value.

- Ranking the three candidates for UBD application.

The paper describes the expert system methodology used in the screening process and the results obtained. The detailed economic analysis presented in Phase II of the study would help ADCO determine the benefit that underbalanced drilling could provide compared to competing conventional drilling & completion technologies.
Integrating Advanced Production Logging and Near-Wellbore Modeling in a Maximum-Reservoir-Contact (MRC) Well
Authors: Mubarak S. , Al-Afaleg N. I. , Pham T. R. , Zeybek M. , Soleimani A.
Published: December 2007

This paper presents a methodology for more accurate reservoir characterization with a field example of Maximum Reservoir Contact (MRC) well evaluation using dynamic production logging and near wellbore simulation modeling. Ultimately, once the results of these analyses are input into geological models and field simulators, more accurate answers would be obtained.

The study was initiated to honor advance production logging results in inverse manner and to explain crossflow behavior. MRC well consisted of two lateral and motherbore and production logging results provided contributions of each lateral (3 rates) and crossflow during shut-in (total of 4 rates during survey) and during small choke. These measurements and results suggested that the choke size should be optimized for better production and drainage strategy.

Comprehensive data integration was performed for more accurate modeling, including all production and injection histories of offset wells and drilling history.

Fine unstructured grid refinement was utilized for near wellbore modeling. The multilateral well has been numerically modeled including friction to match production logging results and to obtain horizontal and vertical permeabilities between layers. Crossflow was also reconstructed in a quantitative manner. To the best of our knowledge, this is the first study with actual data honoring flow contributions and capturing such observations. Sensitivities were also carried out for injection and production history on crossflow behavior.
Inflow Profile Control in Horizontal Wells in a Fractured Carbonate Using Swellable Elastomers
Authors: Welling Rudy W. F. , Marketz Franz , Moosa Riyadh , Riyami Noha , Follows Edward J. , de Bruijn Gerbert , Hosny Khalid
Published: December 2007

A fractured carbonate field is developed via Gas Oil Gravity Drainage in the upper layers and water flood in the deeper layers. Due to the injection of gas and water into this fractured reservoir, horizontal wells tend to gas or water out, impairing the matrix drainage process. Different well and reservoir management techniques are used to prevent this from happening or to control the inflow when it happens. One such technique is to segment the bare foot horizontal open hole section with swellable rubbers and create up to 6 discreet zones of inflow, separated by 3 1/2 " tubing. The inflow from each section is currently controlled by a coiled tubing operated sliding sleeve. In the future it is anticipated that control will be done using hydraulically operated sleeves.

Up till November 2006 eight horizontal barefoot oil producers have been re-completed with swellable packers. This paper concentrates on water shut-off and addresses the design, installation risks and mitigation, the impact of zone shut-off on well production performance, and the actions taken to optimize the production of each well by logging the well and shifting the sleeves.
Optimization of High-Pressure, High-Rate (HP/HR) Gas Wells in a Giant Offshore Field
Authors: Benesch J. M. , Gahr J. Z. , Al-Mohsin A. H. , Schmidt M. H.
Published: December 2007

An extensive large bore gas well drilling program is ongoing for the development of Qatar's North Field. This massive offshore carbonate field contains abnormally-pressured natural gas produced from the Khuff reservoir at ~10,000-ft TVD. In the most extensive application of large bore wells in a single field development, this program involves a large number of wells drilled under challenging subsurface conditions. These large bore wells maximize the gas contribution of each well and reduce overall field development costs by minimizing the number of wells and facilities required. Significant design and operational enhancements made during the program have dramatically reduced drilling time and cost without compromising safety or integrity. In addition to reducing drilling time by over 40%, specialized procedures have been developed for managing major challenges including complex lost returns and well control events.
Drilling and Completing Intelligent Multilateral MRC Wells in Haradh Inc-3
Authors: Al-Bani Fahad , Baim Ahmad Shah , Jacob Suresh
Published: December 2007

The Haradh Increment-3 (HRDH Inc-3) development, commissioned in March 2006, has added significant volumes to Saudi Aramco's daily production capacity. The development has 73 wells comprising of 28 water injectors, 13 observation and 32 producers. 28 of the 32 producers are intelligent completions in multilateral wells. The Maximum Reservoir Contact (MRC) wells with multilateral systems improve the reservoir contact while reducing the drawdown on the reservoir. The intelligent completion system allows the inflow from each lateral to be controlled from the surface without well intervention. The combination of the multilateral and intelligent completion system is expected to enhance field recovery by preventing/delaying water coning and improving sweep efficiency. HRDH Inc-3 may be considered as a milestone in the industry where the field development is focused on the "Smart Multilateral Systems"

Application of cutting edge technologies like rotary steerables system (RSS), realtime drilling data transmission, Geosteering, non damaging fluids, multilateral systems and intelligent completions have helped in achieving maximum effective reservoir contact and delivering the wells ahead of schedule.

The producer wells were drilled with three or four laterals depending on the location of the well. Each of the laterals has around 4,000 ft of reservoir contact and the average reservoir contact for each well is over 14,000 ft.

The wells are constructed as Technology Advancement in Multi-Lateral (TAML) Level-2 system where openhole laterals are drilled out of the motherbore that is cased and cemented. The intelligent completion system comprises of pressure and temperature sensors, production packers and hydraulically operated downhole valves that can be controlled from the surface. The downhole valves are placed in the motherbore to control inflow from each lateral.

The paper presents details of the field planning, drilling and completion practices. The challenges faced in drilling and completing these complex multilateral MRC wells within a tight schedule and the important lessons learned will also be covered in the paper
Lubricants Enabled Completion of ERD Well
Authors: Holand Jonny , Kvamme Svein Arne , Omland Tor Henry , Saasen Arild , Taugbøl Knut , Jamth John
Published: December 2007

Lubricants are often added to the completion or drilling fluid, in order to reduce friction between tubular equipment run into the well, and the wall of the well. This paper shows in detail how the addition of a lubricant to an oil based drilling fluid affected the lubricity significantly in the second of two comparable drill pipe runs, resulting in historically low coefficients of friction.

The use of an ultra-low viscosity drilling fluid resulted in a clean metal to metal contact between the casing and the drill pipe, which caused high static friction. The selected lubricant was designed to stick to metal surfaces, and the result showed that the lubricant had a significant effect on both torque and drag forces. In the drilling phase, the apparent static friction factor decreased from 0.23 to 0.13 and the dynamic friction factor from 0.13 to 0.11. Comparing the two 8 ½" sections drilled, the average off-bottom torque was reduced by 25 % after adding this specific lubricant to the drilling fluid.

In selecting the lubricant, different lubricants were tested using a novel laboratory instrument capable of measuring the coefficient of friction at elevated pressure and temperature. These laboratory measurements proved to be consistent with the observed effect of the lubricants in the field.
A Step Change in Openhole Gravelpacking Methodology: Drilling-Fluid Design and Filter-Cake Removal Method
Authors: Law Matthew , Chao George W. , Ab Alim Hafeez , Samuel Elsamma , Ejan Aziz , Hameed Mohsen Abdul , Samuel Mathew
Published: December 2007

The major trend of completion method in offshore reservoirs with sand control requirement is Horizontal Open Hole Gravel Packing (OHGP). Though gravel packing is a proven method to stabilize the well bore, controlling sand and maximizing productivity, it entraps the filtercake formed by the reservoir drilling fluid. This results in low production rate and consequently leads to the requirement of high drawdown pressure. Hence it is imperative that the filter cake be removed uniformly to ensure lower drawdown pressure, and even flow distribution throughout the producing interval of the well.

A review of the completion methodology in poorly sorted unconsolidated sands with high fines content in Brunei also indicates that the situation is not much different from above, demanding to lower production drawdowns while delivering production quotas. The lower drawdown extends the integrity of sand control completion jewelry, reduces water influx, fines migration, and increases recovery factors and reserves. The Brunei Shell Petroleum's (BSP) Tali asset strategy has been driven towards highly deviated wells with Open Hole Gravel Packs. OHGP requires a high quality mud filter cake to be maintained throughout drilling and placement of the gravel pack.

Traditional methods with acid to breakdown filter cake have been proven ineffective as they cause highly conductive wormholes that contribute the majority of production. The acid can also react with sensitive clays in sandstone resulting in secondary and tertiary precipitations. Additionally, acid reacts with the screen metal causing variation in opening tolerances, which is unacceptable for these poorly sorted high fines content sands.

The objective of this paper is to present the results of the application of a clean up fluid containing a chelating agent and an enzyme to dissolve the filter cake formed by the drilling mud. Use of enzyme breaker and chelating agent used in the clean up fluid helps to promote the dissolution of starch and calcium carbonate components used in the drilling fluid mud. Laboratory test procedures, results, field case histories and production results are discussed in detail. Laboratory tests include the effect of this cleaning up fluid on the filter cake formed by different drilling mud composition. Field case histories comprise of the gravel packing of the oil producer well and subsequent treatment with the proposed clean up fluid.
How Much is Left of Your Centralizer After Exiting a Casing Window in an Extended-Reach Horizontal Multilateral? Modeling, Yard Tests, and Field Results from Alaska's West Sak Development
Authors: Peterson E. M. , Greener M. R. , Davis E. R. , Craig D. T.
Published: December 2007

The West Sak viscous oilfield on the North Slope of Alaska is currently being developed with extended reach multilateral wells, with departure to depth ratios up to 5 to 1, in which horizontal slotted liners are utilized in conjunction with a TAML level 3 multilateral junction system. Centralizers are considered necessary on the slotted liners to avoid slot plugging, reduce drag, and limit differential sticking. Selection of proper centralizers to run through a casing exit, without a whipstock in place, has been key to ensuring a successful multilateral installation.

Several failures of centralizers run on liners through casing exits have resulted in significant drilling lost time associated with fishing and milling pieces of centralizers in order to place the wells into proper service. After three such failures, the requirement to study the passage of a centralized liner through a casing exit became essential. A surface test fixture was utilized to simulate liners run through a casing exit to test several potential centralizer candidates using the loads estimated from modeling. Torque and drag modeling provided the side force estimates exerted on the liner and centralizer as they passed through a casing exit.

This paper will the discuss the liner centralizer installation problems prior to the testing program, detail the modeling used to determine the loads exerted on the centralizer at the casing exit, show the results of the yard tests conducted on several commonly utilized industry centralizers, and make recommendations for proper liner centralization in multilaterals.
Cement Seal Units Eliminate Interzonal Communication
Authors: Elzeghaty S. Z. , Kinzel Holger , Colvard R. L.
Published: December 2007

SEAL UNITS prevent gas/fluid movement at the interface between the outer surface of the casing and the inside of the cement sheath. In spite of the improved practice of releasing pressure on the casing after the top plug bumps, investigations by different research and development groups confirm that leakage at this interface is very possible. When subjected to differential pressures, often encountered in completing or producing a well, inter-zonal communication at this point will occur, like "channeling" in the remainder of the annulus. This will prevent efficient production of the producing zone or cause stimulation work (fracturing, acidizing, etc.) to be ineffective due to uncontrolled fluid migration in the annulus.
Two Salt-Dome Wells Sucessfully Drilled with Casing-While-Drilling Technology
Authors: Veltri David , Warren Tommy , Tessari Robert
Published: December 2007

Recent conventional wells drilled around the Chachaloula Salt Dome field in South Louisiana have been drilled directionally from central pads due to wetland environmental issues. These wells often encounter borehole instability and lost circulation drilling problems. Some take multiple sidetracks to reach the target and others are abandoned before reaching the intended target depth.

Two wells were drilled with Casing while Drilling (CwD) technology in mid-2005 to depths similar to conventionally drilled offset wells. Both wells successfully reached the target formations. The second well delivered a 25% savings based on the average offset cost.

The CwD wells utilized rotary steerable directional technology for deviation control through the steeply dipping beds. Operations conducted through the casing drillstring included a plug-back and sidetrack and two fishing operations for failed downhole tools. These operations were performed without tripping the casing out, thus showing the versatility of the CwD technology.
Utilizing the Effect of Nitrogen To Implement Light-Oil Air Injection in Malaysian Oil Fields
Authors: Mohiuddin Zeeshan , Raja D. M. Anwar , Saaid Ismail Mohd
Published: December 2007

Air injection has been used as one of the enhanced oil recovery (EOR) techniques especially to extract the heavy oil. Nevertheless, a number of applications of in-situ combustion (ISC) for light oil reservoirs have been also reported successful. In light oil reservoirs, the thermal method of EOR is known as light oil air injection (LOAI). This paper discusses the research work carried out to find the potentials of LOAI in Malaysian light oil reservoirs. Screening criteria has been developed from which Dulang E12-14 reservoirs were short listed for further study. In research study, combustion was assumed to occur in low temperature oxidation (LTO) to eliminate the complexities of combustion process. In simulation studies, effect of nitrogen was utilized in place of air, as nitrogen has various common properties with air due to the higher percentage in it. By this assumption, the early potentials of LOAI can be identified without performing experimental studies. This method could provide an easy alternative to assess the potential application of the LOAI technique for depleting Malaysian light oil reservoirs. Experimental studies may need to be carried out if simulation results show the significant amount of incremental oil.

Results of the simulation work seemed to suggest that the LOAI could significantly increase the oil recovery factor from the depleting Malaysian light-oil reservoirs. The EOR screening software PRIze also reflected this trend. Besides this incremental recovery, the volume of produced gas also increased.
Deepwater Drillship Operations and Upgrade
Authors: De Bonnafos O. , Zijderveld G. H.
Published: December 2007

Since 1999 the two drillships Pride Africa and Pride Angola have been operating in Angolan offshore waters. From their initial startup both vessels have been deployed in a deepwater field development role and operated under long term contracts.

This paper describes the operational experience since the start up of both vessels within their field development role; the successes and the shortcomings resulting in lessons learned which formed the base of a project plan to further enhance the operability of the vessels.

Late in 2004 and early in 2005 both vessels were docked in Cape Town for the 5 yearly special survey and maintenance upgrades. Works were executed which reflected additional requirements requested by the operator as well as upgrades planned by the drilling contractor.

The paper will address the following key elements in operating and upgrading these deepwater vessels successfully (1) Implementing of the lessons learned with respect to the originally installed systems on both units, both from a marine and operational perspective, and improvements made based upon these experiences; (2) the development of a project execution plan indicating key elements for upgrade; (3) the preparation of the docking of both vessels, specifically with respect to timing, logistics and the docking itself; (4) the actual execution of the docking with the lessons learned; (5) the subsequent operational and maintenance experience as a result of the upgrade process of both vessels.
Principle of a New Flow-Unit Auto-Subdividing Method and Its Application in DaQing Oilfield
Authors: Zhang Fuming , Shao Cairui , Li Hongqi , Jiao Cuihua , Liu Hongtao , Li Yuanjiang
Published: December 2007

This paper discusses the method on how to subdivide the reservoir into zones based on flow-units. Based on the thought of "inner homogeneity" in flow-unit, a new and reasonable auto-subdividing method named "slicing-merging" was proposed in this paper. And the main characteristic parameters used by this method, such as FZI (Flow zone indicator) and RQI (Reservoir quality index), were obtained based on core-analysis and well-logging data. This technology can be used to subdivide the reservoir into flow-units and identify the type of flow-units simultaneously. This paper analyzed the rationality and petroleum geological meanings. Its application was shown by some examples from DaQing Oilfield.
Wellbore Stress Indicators while Drilling: A Comparison of Induced Features from Wireline and LWD High-Resolution Electrical Images
Authors: Lindsay G. , Ong S. , Morris S. , Lofts J.
Published: December 2007

Wellbore stability analysis utilising wireline borehole images is well established. Today high resolution while drilling (LWD) images are available and they offer information in real time as well as the opportunity to acquire time-lapse information through re-logging while tripping. This paper discusses the usefulness of applying LWD image logs versus wireline image logs for determining wellbore stress through actual well examples. We discuss some benefits to early data acquisition as well as benefits due to technology.

We observe that the comparison of post-drilling images with detailed wellbore images acquired at time of drilling indicates that different features can be observed. These differences relate to the dynamic drilling environment and changes in the wellbore surface with time. In one example, both break-out and tension induced fractures are observed together, indicating an instability not predicted by traditional pore pressure models or seen in post-drilling wireline logs.

Today's drilling practices are continually pushing well design boundaries, for example in the areas of extended reach drilling, high pressure and geometrically complex well design. These scenarios require increasingly sophisticated wellbore stability management. With the real-time information within while-drilling high resolution images, a method is proposed for real-time incorporation in to well bore stability management that will reduce risks in these challenging well conditions.
Improved Well Construction Enabled by Next-Generation Top-Drive Casing Running and Drilling Tools
Authors: Abrahamsen Egill , Reid Doug
Published: December 2007

This paper discusses casing installation methods with a new generation top drive casing running system versus conventional and mechanized casing running methods. The enabling technology provides opportunities for change in conventional well construction methods by using the option to rotate casing strings at high speed, instantly circulate and reciprocate when required, and even push down the rotating casing into the well. The paper highlights how this technology, when combined with drilling with casing tools and expertise, can significantly reduce well construction costs, thereby providing earlier production at less risk.

Applications include: drilling with casing from rigs with top drives; casing installation in predrilled wells; risk mitigation for casing installation in extended reach, deviated, and troublesome wells; removing flat spots in the well construction curve through methods such as "hole cleaning with casing," drilling and reaming with casing, and more.

Results, Observations, and Conclusions:

The top drive casing running system enables improved safety through simpler and less personnel intensive operations, by combining several conventional casing tools into one system: Power tong, main hoisting elevator, single joint elevator, fill-up and circulation tool, weight compensator and, casing stabbing.

Lab and field test results have proven that the new technology provides greater casing running efficiency, increased safety through personnel reduction and remote operation, and drilling with casing capabilities.

Significance of Subject Matter:

Step change in technology allowing oil & gas operators to increase drilling performance, improve safety, and reduce well construction costs.
Recent Metal-to-Metal Sealing Technology for Zonal Isolation Applications Demonstrates Potential for Use in Hostile HP/HT Environments
Authors: Garfield Garry , Mackenzie Gordon
Published: December 2007

Zonal isolation tools, including bridge plugs and straddle systems, using metal-to-metal sealing technology in place of conventional elastomers may radically challenge existing engineering philosophies by providing a pressure sealing system capable of exceeding the limitations of other existing sealing technologies and eliminating many traditional failure modes. Metal-to-metal sealing technology is an innovative type of high expansion seal that uses expanding metal to form a high integrity pressure seal and incorporates an extraordinary seal performance envelope that cannot be achieved by conventional elastomeric seals. The seal design utilizes the controlled application of load to expand the metal seal to achieve a fully formed pressure barrier which allows for the metal-to-metal seal in bores of up to 160% of the original seal diameter.

The metal-to-metal seal has the potential to change the way downhole equipment provides pressure integrity in HPHT environments. In the well servicing market, recent applications of the metal-to-metal seal and the latest lab testing have suggested the prospective of the technology for products in the HPHT arena. Metal-to-metal sealing technology could make well suspensions and intervention possible in hostile HPHT wells that were previously deemed inoperable by the complete removal of elastomers from the design. Ideal for HP/HT applications, metal-to-metal sealing devices can be easily deployed on slickline, electric wireline, coiled tubing, or drill pipe to save operator rig time in areas where cost savings are critical.

Case studies of the high performance characteristics of the metal-to-metal sealing technology in terms of design, testing, and implementation will recognize the alignment to the increased demands of HP/HT applications.
First Gas Field Developed Using Exclusively Dope-Free Casing and Tubing Connections—Statoil Snøhvit
Authors: Carcagno Gabriel , Castiñeiras Tomás , Eiane Dag Johan
Published: December 2007

The recent development of dope-free solutions for tubing and casing premium connections provides a real and proved alternative to traditional thread compounds like the well known API Modified thread compound(1), and the proprietary environmentally-friendly thread compounds. Among other advantages, the selected dope-free solution allows to solve the legal limitations to operate with standard compounds in very environmentally-sensitive areas as the Barents Sea, while providing a performance that fulfill nowadays requirements for tubing and casing applications, for different materials as C-steels, 13Cr and Corrosion Resistance Alloys. This paper describes the main concept and features of Dopeless™, a fully dry dope-free solution developed through extensive testing and laboratory evaluation, and the first 100% extensive field application of this solution in the Sn0vhit field of Statoil in the Barents Sea. In such field, all the tubing and casing strings were ran with dope-free proprietary premium connections, becoming the first field worldwide in adopting this technology for all the tubing and casing strings. The challenges of a new technology application in a very demanding initial experience were managed through a good communication and cooperation between the Dope-free connection manufacturer's development team and the operator technical team, which allowed to understand and to manage the features and challenges of not only a new product but a real new technology. As result of the experience, 40 tubing and casing strings of dope-free premium connections from 7" to 14" were run, using a floating rig equipped with automatic handling, with very acceptable results in terms of running performance, and without any particular event related to this. The results obtained, as well as the lessons-learnt and possible improvements are analyzed and discussed.