bluuebunny/crossref_metadata_2025_split huggingface dataset:
Troika Field: A Well Failure, and Then a Successful Workover
Authors: Gillespie G. , Angel K. , Cameron J. , Mullen M. 
Published: December 2007

Abstract
The second phase of Troika field development began in 2000. Two wells were planned to develop reservoirs adjacent to the primary Troika reservoir. The planned wells were deep, single zone, frac packed, subsea completions.
The first of these wells was the Green Canyon Block 201 TA-6 ST#1 Well (TA-6). It was planned to have a well angle exceeding 40°, 7 in. production liner and 4 in. base pipe prepacked screens. After drilling the well, open hole logs showed the target reservoir was approximately 170 ft. thick, but there were two significant shale breaks within the reservoir. During completion, there were problems getting the 7 in. liner to bottom, so a 5-½ in. liner was run. The 5-½ in. liner was cemented in place, and then squeezed due to possible channels across the completion interval. The well was perforated and a 2-⅞ in. reduced diameter prepacked screen was run without difficulty.
During the frac packing process, TA-6 did not have a live annulus, so circulating in this small casing was not possible. In addition, the crossover tool failed during pumping operations. This resulted in frac sand and gel plugging the wash pipe. Consequently, the pressure gauges could not indicate whether a good frac pack was achieved.
TA-6 started production in November 2000 and produced 3.91 million barrels of oil and 4.48 billion cubic feet of gas with water cut slowly increasing to approximately 10% before a gravel pack failure occurred in January 2002. The well was cleaned out and a 1.3 in. diameter through tubing screen insert was run inside the failed screen. No attempt was made to place gravel pack sand between the screen insert and the failed screen. Since the screen insert was installed, TA-6 has produced over 1.95 million barrels of oil and 2.7 billion cubic feet of gas with water cut less than 3%.
This paper will evaluate this well's history using BP's new maximum flux guidelines1. In addition, it will use a new erosion model to evaluate both the probable cause of the well's failure and the operating conditions of the successful workover completion.
Simplifying Hydraulic Fracturing—Theory and Practice
Authors: Hibbeler J. , Rae P. 
Published: December 2007

Abstract
Although hydraulic fracturing is a routine stimulation technique in many parts of the world, it has seen limited use in areas such as Asia Pacific for example. Among the hurdles to fracturing in traditional non-frac markets is the common perception that fracs are expensive, risky, complex and difficult to design. This perception has been challenged in recent years by the promotion and technical validation of simplified fracturing treatments aimed, primarily, to address near-wellbore skin damage. The new approach, termed Skin Bypass Frac (SPF), is low cost, safe, simple, and easy to design. In fact, by careful fluid selection, these small treatments can be pumped from an offshore drilling rig using nothing more than cementing equipment. By simplifying fracturing to this degree, there is now a safer and more environmentally-friendly way to remediate skin damaged wells, without the implicit dangers of acidising.
To date, this technique has been used in a number of diverse situations yet, despite its simplicity, it has yet to be practised on a widespread basis. Results indicate that if candidate selection is good, production increments can be significant, particularly in those wells with skin damage. To make candidate selection effortless, a set of criteria was developed to determine which wells would benefit the most. Parameters such as permeability, zone height, estimated skin, reservoir mobility, zone isolation and proximity to water were all considered in this selection model.
This paper reviews the practical theory of using small simple frac treatments to improve productivity in damaged wells and wells with small sands where higher recovery rates are desired. The concept of LCP is discussed and a model is put forward to perform frac jobs with cement units, which may come to be known as universal pressure pumping units.
The Feasibility Study of Using Underbalanced Drilling in Iranian Oil Fields
Authors: Shadizadeh S. R. , Zaferanieh M. 
Published: December 2007

Abstract
Conventional overbalance drilling in naturally fractured reservoirs causes the invasion of mud and fine rock fragments into the fractures, which result to decrease the productivity of hydrocarbon from these reservoirs. In some cases, the sever problem of mud invasion into the fractured prevents flowing of HC's into wellbore after initial well completion especially in the depleted fractured Iranian reservoirs.
Underbalanced drilling (UBD), with a reduced exerted pressure down in the wellbore avoids the build up small solids being deposited on the sides of the hole, it also prevents the invasion of mud and fine rock fragments into the fractured formation which, together, help to improve the productivity of hydrocarbon from the reservoir. UBD method avoids many of the problems associated with the use of conventional drilling such as stuck pipe. Also, the rate of penetration increase by 2 to 5 folds by using UBD method, which resulted in low cost of drilling.
The main objective of this study is to investigate the use of UBD method in the fractured reservoirs in southern Iranian oil field in terms of drilling equipment's, drilling operation, drilling fluid, formation characteristics, and economic evaluation as compared with conventional overbalance drilling method.
Unconventional Uses for Unconventional Oil
Authors: Ehlig-Economides C. A. , Barrufet M. , Longbottom J. R. , Velu B. P. 
Published: December 2007

Abstract
The correlation of job loss with disruptions in oil supply underscores the importance to the US economy of transportation, which is 95% dependent on oil, the only primary fuel currently being imported by the US in massive quantities. One solution is to promote oil supply stability, but at a sustained higher price, by migrating to unconventional primary fuel resources such as heavy oil, shale oil, tar sands, orimulsion, or coal, that are available on the North American continent. Another solution would be to shift as much transportation as possible to electrically powered vehicles because electricity already uses a diverse selection of energy resources. This paper compares the use of unconventional oil for electric power generation to its use as a source of transportation fuels.
Like coal, unconventional oil can be burned for power generation, or alternatively, both coal and heavy oil gasification processes are described in the literature. Gasification processes can make more efficient use of the energy content, and they reduce atmospheric emissions.
The comparison considers cost, energy efficiency, and environmental impact of the two transportation options on a "well/mine to wheels" basis as well as the estimated coal and unconventional oil reserves.
Combined High-End Technologies Deliver Increased Efficiency in Low-Cost Drilling Environment: Case History in a Western Siberian Field
Authors: Lischuk V. Y. , Brown A. A. , Bakici A. M. 
Published: December 2007

Abstract
In recent years, new technology has significantly improved the economics in high-cost drilling environments worldwide. In a western Siberian case, two service providers recently combined their technologies and operating procedures to yield reduced drilling costs and overall improved project economics. The service companies cooperated to produce the best results for the project and the customer.
This paper describes a project in western Siberia, a well-developed, low-cost environment. Drilling performance had to be measurable and repeatable. The major challenge was to design a polycrystalline diamond compact (PDC) drill-bit/mud-motor combination for use on Russian-made rigs to achieve performance improvement. Issues included tool face control, initial cost of PDC drill bits, and in-country rigs incapable of delivering adequate torque and hydraulic horsepower to the PDC bit.
Applied technology included a new PDC bit designed for steerable motors in projects in which tool face control was a primary concern. The PDC bit was optimized for formation characteristics and motor capabilities by use of depth-of-cut control (DOCC) technology. This optimization reduced torque fluctuations that, in turn, increased tool face control while sliding and increased the rate of penetration (ROP) in rotary mode. Maximizing the benefit of the bit, a special motor was used that was capable of delivering high torque to allow consistently high ROP while maintaining trajectory control. This combination resulted in successful high-performance drilling.
The objective was to complete intervals normally requiring several bits with a single bit run at higher average ROP. The results were indeed rewarding. There were 66% fewer trips per 8½-in. section, on average, compared to offset wells, in conjunction with a 37% reduction in drilling hours, equating to an ROP improvement of 27%. In spite of the additional cost of the PDC and high-torque motor, the system delivered the lowest cost per foot vs. the best offsets from three drilling pads examined. An important feature of the application was that the bit/motor combination was run on a risk/reward incentive program.
What is the Impact of Fracture Modelling on Reservoir Performances and Reservoir Simulation: Examples
Authors: Le Maux T. , Fonta O. , Sarda S. , Godail L. 
Published: December 2007

Abstract
Natural fractures may have a significant role on reservoir performances: fractures may affect wells’ productivity or injectivity. Fractures can also control sweep efficiency and water/gas breakthrough within the reservoir. The purpose of this paper is to present an innovative and rigorous method to identify the main types of fractures, to predict their occurrence in the reservoirs and to determine the hydraulic properties of the different fractures sets. Based on a multi-discipline integrated approach, the end product is a robust and reliable 3D model of fractures properties (porosity, permeability and matrix block size) directly usable for reservoir simulations and predictions.
In the first section of this paper we present how to handle multi scales fractures characterisation through integration of multi disciplinary dataset. In the second section, it will be shown how the fracture characterisation and modelling can significantly improve the history matching process.
A Simulator for Predicting Thermal Recovery Behavior Based on Streamline Method
Authors: Pasarai U. , Arihara N. 
Published: December 2007

Abstract
The general tendency in simulation technique of thermal recovery processes has been to use the fully implicit finite difference method to solve the mass and heat transport. The method has been proven favorable to handle rapidly changing properties and complex physical mechanisms encountered in the processes. However, this method is limited in the grid size due to restrictions in computational power. In addition, the method could also erroneously predict recovery performance if care is not taken in the choice of numerical scheme. For example, when the mobility ratio of the displacement is unfavorable, calculations often result in exaggerated global sweep and may adversely affect reservoir performance prediction. Local grid refinement is a natural process to handle this situation but requires a great amount of memory and high computational cost. This becomes inefficient when multiple simulations are required to assess a wide range of reservoir development scenarios.
An alternative approach to solve the problem is to use the streamline method. Because fluid transport occurs along streamlines rather than between discrete grid blocks on which the reservoir pressure field is solved, the problems associated with the fully implicit finite difference method are minimized and the simulations can run much faster. This is supported by the results presented in this paper. We applied the developed thermal streamline simulator to a hot water-flooding process. Test simulations were performed in the two-dimensional (2D) areal quarter five spot pattern. The heavy oil reservoir is assumed to have undergone cold water injection. Water at the initial conditions is about 45 times more mobile than oil, which leads to unfavorable displacement. The results of simulations are compared with those from the fully implicit method using the 5-point and 9-point finite difference schemes. Although simplified, the simulation demonstrates the main features of our simulator.
Wellbore Cleanup by Water Jetting and Enzyme Treatments in MRC Wells: Case Histories
Authors: Al-Otaibi M. B. , Nasr-El-Din H. A. , Altameimi Y. M. 
Published: December 2007

Abstract
A number of maximum reservoir contact (MRC) wells have been drilled and completed in various fields (sandstone and carbonate) in Saudi Arabia. The drilling fluid, water-based mud, consists of xanthan, starch, polyanionic cellulose polymers and bridging agents like sized calcium carbonate or salt particles. Cleanup of drilling fluid filter cake in long horizontal wells completed as an open or cased hole is a challenging task. The obstacles encountered are the difficulty to ensure contact of the treating fluids with the filter cake throughout the whole interval, as well as controlling the reaction rate between the breaker and the filter cake to ensure uniform removal of the filter cake.
Today, several chemical and mechanical systems are available to remove the polymeric and bridging agents in oil and gas producers and water injectors. Chemical means (oxidizers and acids) have limitations, which can adversely affect well performance. Oxidizers and acids are highly reactive and non-specific species. Reservoir heterogeneity complicates the cleaning process. There is a need for cleanup fluids that have a delayed effect on filter cake-integrity to obtain a uniform distribution over the horizontal interval.
Specific enzymes can degrade xanthan and starch polymers in the filter cake with lower removal rates. A low reaction rate promotes a more uniform cake cleanup and should result in higher production rates. Field results indicate that utilization of enzyme treatments is very effective technique in removing drilling mud filter cake. The production rate for treated wells reached the target value without the need to acidize the well.
High pressure water jetting technique has been utilized to mechanically remove filter cake. Field results obtained from many injectors indicate that this technology has several advantages such as simplicity of use, cost effectiveness, and high success rate. This paper will discuss field application of specific enzymes and water jetting in gas, oil, and water wells. It will also highlight the advantages and disadvantages of each method based on field data.
The Mechanism and Application of MEOR by Brevibacillus Brevis and Bacillus Cereus in Daqing Oilfield
Authors: Hou Z. , Wu X. , Wang Z. , Han P. , Wang Y. , Xu Y. , Jin R. 
Published: December 2007

Abstract
The mechanism of petroleum hydrocarbon degradation by the selected bacteria Brevibacillus brevis and Bacillus cereus is studied based on the metabolite analysis. The result shows that bio-oxidation processes, especially those called unconventional subterminal oxidation, terminal and double-terminal oxidation, are the main pathway by which the bacteria will convert petroleum hydrocarbons into fatty monoacids, hydroxyl fatty acids and dicarboxylic acids. This, for the first time, makes an important correction to the prevailing opinion which says that long-chain hydrocarbon molecules can be degraded into short-chain hydrocarbon molecules instead of acid compounds. The study explains how the bacteria ingest petroleum hydrocarbons as well as the correlation between ingestion modes and the active substances present in crude oil. The pathway to produce bio-surfactants and the correlation between produced bio-surfactants and oil metabolism are also discussed in this paper.
From 2002 to 2004, Brevibacillus brevis and Bacillus cereus were applied in the microbial huff and puff as well as the Microbial enhanced waterflood test in Daqing excessively low permeability (1.0md-25md) reservoir. After bacteria injection, 44 among the 60 huff and puff wells shows a significant oil production response—the accumulative oil increment reaches 6012 tons and the input-output ratio amounts to 1: 6. The Microbial enhanced waterflood test carried out in June 2004 also provides a satisfying result. After the injection of bacteria, the pressure in the two water injectors decreased more than 2MPa, which results in an injection capacity increase. In late 2004, the fluid production of the 5 producers (the total number is 8) is increased from 29.5 tons per day (before bacteria injection) to 44.4 tons per day, and the corresponding oil production is increased from 20.8 tons per day (before bacteria injection) to 36.9 tons per day. These make MEOR a very promising oil recovery method in Daqing Oilfield.
Water Flooding Efficiency in a Scenario of Multiple Induced Fractures, an Applied Geomechanical Study
Authors: Chavez J. C. , Carruthers J. , McCurdy P. 
Published: December 2007

Abstract
Understanding and predicting multiple fracture propagation behaviour whilst injecting water in the layered reservoir of Field A, offshore Nigeria, presents several major challenges.
The water flood efficiency will be affected by the behaviour of each independent fracture during the injection process. For this reason an accurate estimation of the behaviour of each individual fracture and their interdependence are essential for field development.
The principle objective of the study was to find the main factors that controlled the multiple fracture growth behaviour using a 3D fracture simulation model. A water injection well was planned in a reservoir with 5 moderate to high permeability sand layers varying from 6 to 25 feet in true vertical thickness. A further consideration was that the sand layers in the reservoir had depleted from 2600 psi to 1900 psi. A comprehensive lithological and geomechanical model of the reservoir section was constructed for simulating the injection process. As a mixture of seawater and formation water was planned for injection possible chemical effects were also considered in the study. The 3D simulation model of multiple fracture propagation considered thermal and pore pressure effects. In addition, reservoir pressure depletion and particle plugging were also considered.
The behaviour of each individual fracture was shown to be interdependent on the other fractures in the model. The results of the simulations demonstrated that over the first 5 years of planned water injection, the behaviour of the fractures was mainly dependant on the pressure depletion effects at the time of water injection and particle plugging. Critically, the depletion effects were the decisive element in fracture containment i.e. to guarantee vertical growth into only the selected sand sequences. Some scenarios that were modelled showed that for the planned injection flow rates, fracture containment was not possible after one year of injection. However, in these cases, if the injection rate was reduced by around 20% for a limited period, the fracture growth could be controlled. Full rates could be resumed after this reduced injection period. The introduction of such an injection flow rate control (IFC) during the injection period would then allow the fracture containment and water flood confinement into the selected reservoir sequence.
Understanding the variables that influence multiple fracture behaviour allows timely decisions on surface equipment requirements. In addition the operational conditions associated with the injection process are defined. The injection strategy can then be targeted to promote an optimum water flood profile and water placement into only the selected sand intervals.
It is through the process of modelling the multiple fracture interaction and behaviour that the water injection efficiency can be optimised.
Proper Clean Up and Improved Re-Acidization Quadruples Productivity Index in a HP-HT Horizontal Well Heavily Damaged With High-Weight Mud
Authors: Reji E. C. , Al-Medhadi F. , Mater M. B. A. , Stretch T. , Ali A. , Jassim M. 
Published: December 2007

Abstract
The re-acidization of HP-HT horizontal oil well Umm Guddair XXX in Kuwait resulted in a productivity index four times what was seen after the initial acidization. This astounding improvement in the results can be attributed to better acidization through thorough cleaning of the horizontal section prior to the 2nd stimulation, as well as placing the acid in stages and introducing a suitable diverting agent.
High-Permeability Carbonate Zones (Super-K) in Ghawar Field (Saudi Arabia): Identified, Characterized, and Evaluated for Gel Treatments
Authors: Al-Dhafeeri A. M. , Seright R. S. , Nasr-El-Din H. A. , Sydansk R. D. 
Published: December 2007

Abstract
Super-k (carbonate zones of extremely high permeability) can significantly enhance recovery per well in the Ghawar Field. These zones present a challenge at the onset of normal water arrival as the water contribution from these zones dominates the flow in the wellbore—causing either high water-cut or water loading. As a component of the common practices in Ghawar, water shut-off techniques such as the one described in this paper present an effective mechanism to manage water production. This research project has three objectives. The first objective is to identify and characterize super-k zones. The second objective is to identify chemical blocking agents that can be placed in super-k zones without reducing hydrocarbon productivity. The third objective is to identify an effective technique to optimize the size and the placement of the chemical blocking agents.
Concerning disproportionate permeability reduction (DPR), gelant treatments, that rely on the ability of the gels to be placed in the rock matrix adjacent to the fractures and to reduce permeability to water much more than that to hydrocarbons (DPR in the rock matrix); have more significant potential than does application of DPR in the fracture. A high residual resistance factor to oil in the fracture may shut-off oil.
Distances of gelant penetration can be predicted by knowing the pressure drop and controlling the gelation time. Gel properties for a strong gel that reduces permeability to water as a function of polymer concentrations can also be predicted. If pressure drawdown is held constant before and after a treatment, calculations suggest that relatively small gelant volumes may be most cost-effective in our case. The cost of water treatment, the initial water production rate, the oil residual resistance factor, and the pressure drawdown have strong effects on the economic benefits derived from this approach.