bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical Modeling of Forchheimer's Equation to Describe Darcy and Non-Darcy Flow in Porous Media
Authors: Belhaj H. A. , Agha K. R. , Nouri A. M. , Butt S. D. , Vaziri H. H. , Islam M. R.
Published: December 2007

This paper adds a new dimension to fluid flow in porous media by replacing Darcy's equation with Forchheimer's equation, which in fact takes in consideration both Darcy and non-Darcy flow behaviors. Mathematical derivation of the diffusivity equation based on the Forchheimer equation has been accomplished for linear flow in both one- and twodimensional cases.

Numerical simulation of the new diffusivity equation has been achieved in both cases of Darcy and non-Darcy (Forchheimer) domains. Both numerical models have been tested and verified giving very reasonable accuracy in describing flow characteristics of Darcy and non-Darcy behaviors. Interestingly, a new dimensionless number "Be" relating β (mainly a function of permeability and porosity), velocity, density and viscosity has been introduced to differentiate between Darcy and non-Darcy flow in porous medium for any types of rock and flowing fluid. This new dimensionless number is far from being considered declaration of turbulence flow in porous medium rather the energy loss is contributed to the nature of both flowing fluid and the porous medium. Theoretically, the break point of non-Darcy behavior from Darcy's has been found at (Be = 0), for practical use it has been determined that non-Darcy flow would start at the point when "Be" become greater than zero.

A practical range of permeability with porosity changing accordingly, fluid velocity, density, viscosity and the non-Darcy coefficient (β) estimated from different types of available correlations in the literature have been examined using the numerical models obtained. In all cases "Be" remains the same at the point of flow behavior change to non-Darcy.
Effect of Volumetric Failure on Sand Production in Oil-Wellbores
Authors: Nouri Alireza , Vaziri Hans , Belhaj Hadi , Islam Rafiqul
Published: December 2007

Sand production is a major problem being faced by operating oil companies for many years. Sand problems are known to have increased production costs considerably. To-date, the roles of shear and tensile failure modes have been well thought out in studying sand production, but the contribution of volumetric failure mechanism in this phenomenon has been ignored. Even though volumetric failure mechanism has been well studied in looking into the phenomenon of land subsidence, but its role in sand production has been neglected in the past. In this paper, the contribution of this mechanism in sand production is addressed.

In numerical studies, a finite difference based program was used. This program captures the fluid/solid interaction with complete rigor. In the experimental part, uniaxial strain condition was applied on some synthetic samples to examine volumetric failure mechanism, while traditional triaxial tests were performed on the same type of samples to learn about shear characteristic of the material. The mechanical parameters obtained from these tests were used in the numerical model that covers all tensile, shear and volumetric failure mechanisms.

By using numerical and experimental means, it was discovered that volumetric failure mode, i.e. pore collapse, has a significant contribution in sanding. Initially at the well face, only shear and tensile failure may take place, but pore collapse can be triggered in a zone very close to the cavity hole. Subsequent to production of shear or tensile failed material from the open face, pore collapse induced disintegrated material may be exposed to cavity face, and potentially massive sanding may take place.
Development of Highly Durable Materials for Drilling Hard and Abrasive Rocks
Authors: Mori Nobuyuki , Moriguchi Hideki , Ikegaya Akihiko , Shioya Yutaka , Ohbi Katsuhiro
Published: December 2007

The paper presents an overview of the development of the material, which is highly durable against wear and chipping, and can increase the lifetime of roller cone bit inserts while drilling hard & abrasive formations. And the paper also details the design and structure of the new materials referred to as Co-composition graded cemented carbide.

The new sintering process achieves the goal of enabling the development of graded composition technology to be applied for insert materials. That is, grading the structure with varying percentages of Cobalt along with the varying Tungsten Carbide (WC) grain size and density not only results in maximum wear resistance of the surface layer, but also in the shock resistively of inward structures. In general, cemented carbide performance depends on the amounts of Cobalt used for material cementation. The new materials and their development process eliminate the normal compromises made between breakage and wear resistance.

The advantages as indicated from the test results on conically shaped inserts showed that the samples achieved over eight times the wear resistance of conventional inserts, while the semi-round design insert achieved over twenty times the wear resistance of conventional materials.

The laboratory and bench test sample were designed in accordance with typical rock bit insert designs, and the actual tests simulated drilling rotation and weight-on-bit normalization. This facilitated an environment as close as possible to an actual drilling environment. The paper further details the testing methodology and results and demonstrates the advantages of the new sintering process and material development over conventional materials in rock bit inserts.
An Innovative Solution for Maximizing Productivity from Perforated Completions
Authors: El-Bermawy Hady , El-Assal Hossam
Published: December 2007

Inadequate flow efficiency in perforated wells in cased-hole completions has been a major concern in the oilfield since the first use of perforating gun systems. Because of this, one of the primary needs in design of a perforated completion is the accurate assessment of the efficiency of the proposed perforation scenario to transmit fluid from the reservoir to the wellbore.

Flow efficiency is affected by such conditions as the number of perforations actually open to flow, degree of damage around the perforations, formation physical properties, in-situ stress conditions influencing the perforator penetration, and extent of formation crushing around the perforation. This complex interaction of perforating geometry, formation characteristics, and perforating environment precludes traditional, global solutions to design or analyze perforated completions in order to achieve optimum productivity results. Each case must be addressed individually, and all possible information must be considered; (e.g., Cores, logs and well test results).

Unfortunately, existing industry models used to design and optimize perforated completions are fairly basic and have relied primarily on section I API Perforator Test Data (i.e. perforator penetration and entrance-hole results obtained from testing the perforating system under surface conditions in concrete targets) for predicting downhole perforation performance. Since these models obviously do not reflect the actual reservoir conditions, field performance often falls short of predicted results because an accurate validation method for optimizing the gun selection process has not been applied.

This paper will review a new quantitative method based on the unique properties of the reservoir that has been developed to optimize perforating design for individual wells. The process is based on experimental data from laboratory tests as well as theoretical (i.e. numerical and analytical) modeling to identify optimal parameters needed for efficiency in perforated completions.

Case Histories showing the successful implementation of the quantitative method will be presented. The results attained from the process design technique will be validated against actual post-perforation, pressure-transient-analysis field data to demonstrate the productivity improvement that is possible through the use of this perforating solution.
Managing Wellbore Instability in Sabah Basin of East Malaysia
Authors: Tan C. P. , Hamid Pauziyah Abdul , Chen X. , Yaakub Mohd Azriyuddin , Willoughby D. R. , Wu B.
Published: December 2007

Drilling experience in Alab and Samarang fields in the Sabah Basin highlighted the issue of wellbore stability in the region. A wide range of drilling problems has been experienced, ranging from tight-hole to overpull and stuck pipe, and a range of drilling fluid designs has been implemented. Subsequently, a wellbore stability study was conducted to address the problems in the planned extended reach Alab wells. The aim is to develop a strategy to maintain mechanical and time-dependent stability of the extended reach wells to ensure well constructions encounter minimum wellbore instability-related problems.

This paper describes the outline of the study and the approach adopted in the development of the strategy. The drilling experience, material properties, typical in-situ stresses and formation pressure in the Sabah Basin are presented and discussed. Based on the gathered drilling experience, caliper and composite logs, and laboratory tests conducted on downhole core materials, dominant time-dependent failure mechanisms were identified. Mud weight stability profiles and examples of critical mud weight contour plots which form part of the strategy for designing optimal drilling fluid program are presented.

Comparisons were made between predicted mud weights determined from the contour plots and mud weights used in the field together with associated drilling experience and hole size in a post-drilling review. The comparison showed a good agreement for a low angle well but inconsistent for two high angle wells. The reasons for the inconsistencies and means of reducing the uncertainties of input data required for wellbore stability study are presented and discussed.
Design of Aerated Mud for Low Pressure Drilling
Authors: Gücüyener I. Hakki
Published: December 2007

This paper presents a multiphase hydrodynamic model for design of the aerated mud hydraulics in vertical and moderately deviated directional wells with an angle of less than 20° from vertical. The model is capable of predicting flow pattern and pressure drop in two phase flow through the drillstring and the annulus. Bubbly, dispersed bubble, slug and churn flow patterns are accounted for down flow in the drillstring. In addition to these flow patterns; the annular flow is included for up flow in the annulus. Effect of cuttings loading on the bottomhole pressure is implemented to the model using the effective density concept. Carrying capacity of aerated mud is evaluated by incorporating two-phase flow properties into a cuttings transport model proposed for conventional drilling mud. Pressure drop across the bit is calculated using an adiabatic and frictionless flow model for homogeneous mixture of air and mud.

In this study, the circulating system is divided into a number of small computational intervals to take into account temperature and pressure dependent properties of aerated mud. Based on the proposed model and computational algorithm, a computer program, UNDRILL~S, was developed to predict flow patterns, circulating pressures, optimum mud and air flow rates, bit hydraulics, and hole cleaning. The program provides a useful tool to help planning a low pressure drilling operation with aerated mud.
An Improved Method for Predicting Pore Pressure of Formation in Offshore
Authors: Yongfeng Guo , Xiaojian Jin
Published: December 2007

The authors supplied an improved method for predicting pore pressure of formation in the offshore oil field. And the result to apply the method is decreasing the density of fluid so that protecting the oil and gas layers and speeded velocity of drill when drilling. The paper gives some formula of mathematics and its procedure of introduction. In past the design of drilling obeyed the rule: the density of drilling fluid would be decided by the value of predicting pore of information, and the value would be decided by the highest pressure of formation pore in the same area. The paper put forward a new rule that the designers can ignore few layers of formation that have high pressure in pore, which are the lessen proportion in the whole open hole because a lot of equipment has been used, which are controlled by computers, and many ways have been mature to control wells when meeting high pressure formation. The effect of application speeds up the velocity of drill, and greatly decrease the density of fluid of drilling. So the application of the rule provides a efficient way to protect the layers of oil and gas underground. The improved method had been accepted in a well in the oilfield in Bohai Bay in 1998, and the well became the well of high production well that products 1000 tons oil in a day.
A Study of Drilling Performance of Energy Balanced Roller Cone Bit
Authors: Chen S. L. , Dahlem J. , Rayburn C.
Published: December 2007

A significant research and development effort plus extensive laboratory and field tests have resulted in a new generation of roller cone bits, namely an energy balanced roller cone bit. An energy balanced roller cone bit incorporates three patented features: (1) balanced cutting structure, (2) optimized tooth orientation, and (3) optimized anti-tracking mechanism. This paper details the principles of these three features and their application to rock bit design. Field performance of energy balanced bits is evaluated by rate of penetration, footage drilled, durability of cutting structure, and reliability of bearing/seal system. Significant performance improvement has been observed in the field.
Horizontal Completions — Improvements in Fluid and Tool Technology Continue to Redefine the Application Envelope
Authors: Ali Syed , Grigsby Tommy , Vitthal Sanjay
Published: December 2007

One technological concept that has been capable of successfully coordinating drilling and completion disciplines is horizontal openhole gravel packing. The synergy required to deliver a reliable high-rate well completion has been evidenced in recent completions, and the successful results have brought about the use of horizontal gravel packing as a mainstay completion technique in deepwater development. The technique has been successfully used in Brazil and has shown the same potential in the upcoming deepwater developments in West Africa. This paper will address how and where the concept was started, how the technology has evolved, and lessons learned that are being applied to increase the application envelope and the reliability of this completion method. The review will cover advances in openhole drilling techniques that eliminate openhole tortuosity, gravel-pack fluids that can reduce rig time and enhance well productivity, and improvements in downhole tools that have or will potentially reduce risk while reducing completion cycle time.
Carbonate Rocks Wettability Changes Induced by Microbial Solution
Authors: Zekri Abdulrazag Y. , Ghannam Mamdouh T. , Almehaideb Reyadh A.
Published: December 2007

Contact angles are used to measure the wetting behavior of two immiscible fluids on a solid surface. Fluids are considered wettings if their contact angles with surface are less than 90°, and they are considered non-wetting, if their contact angles are greater than 90°. Because of its influence on other petrophysical properties of reservoir rocks, such as relative permeability, capillary pressure, and the residual oil saturation after a flood, wettability and its direct measure, the contact angle, play a significant role in affecting the recovery from both primary and improved recovery processes.

In this work, contact angle alteration occurring in microbial enhanced oil recovery processes (MEOR) are quantififed and described, along with a study of the factors that would enhance such contact angle alteration. An experimental method for the measurement of contact angles has been developed in which the contact angle is measured as a function of time. Measurements of contact angle and interfacial tension for four different types of UAE crude oil and four different mineralogical rock composition over a range of microbial concentration, salinity, and temperature are reported. Results showed that contact angles for the studied systems increased with temperature, crude oil sulfur concentration and microbial concentration up to a certain concentration, beyond which the bacteria concentration exhibited no effect on the contact angle. Crude oils containing low asphaltene concentration produced a stable contact angle and oils containing high asphaltene concentration produced surfaces with unstable wettability. The mineralogical composition of limestone rocks had no effect on the contact angle of microbial-oil system.
Correcting for Frictional Pressure Drop in Horizontal Well Inflow Performance Relationships
Authors: Archer R. A. , Agbongiator E. O.
Published: December 2007

This paper presents the development of a correlation that corrects for error in horizontal well productivity calculations made by neglecting frictional pressure drop in the wellbore. Frictional pressure drop within the wellbore is frequently a controlling factor on the performance of long horizontal wells. Frictional pressure drop could be especially significant in wells completed with screens and slotted liners. This pressure loss is neglected in traditional inflow performance (IPR) calculations such as those developed by Joshi, and by Babu and Odeh. This study develops a correction that can be added to these analytical IPR relationships to account for friction. This correction is based on a dimensionless group that combines well and reservoir information. It is easy to evaluate and can be readily used in nodal analysis.

The correction was developed on the basis of over 5,000 finite-difference simulation runs using a simulator with the capability to model wellbore friction. These runs spanned a wide range of well and reservoir parameters. The results are presented in terms of productivity error i.e. the flowrate without friction minus the flowrate when friction is included in the model, divided by the flowrate reported without friction. The study found productivity errors as high as 90% in some cases (usually long wells with small wellbore radius). These errors could lead to poor decisions on field development and production facilities. This paper presents a simple way to improve well productivity predictions without requiring a reservoir simulation model to take account of frictional pressure drops in the wellbore.
Effect of Flow Velocity and Rock Layering on Foam Flow: An X-ray Computed Tomography Study
Authors: Zitha Pacelli L.J. , Nguyen Quoc P. , Currie Peter K.
Published: December 2007

The influence of flow velocity and core heterogeneity on foam flow through porous media has been investigated with the aid of X-ray computed tomography (CT). The real time imaging of fluid partitioning, the saturation profiles extracted from the CT images and the pressure drops over several core segments have been analyzed in the light of a mechanism involving capillary and viscous forces. Natural Bentheim and Berea sandstone cores together with nitrogen (N2) foam, stabilized using sodium dodecyl sulfonate (SDS) have been used to conduct the experiments. Geological layering of Berea sandstone was oriented either parallel or perpendicular to flow.

The transient foam flow in cores containing a surfactant solution exhibits a front-like character. The secondary liquid desaturation reported previously is barely modified by increasing foam quality and leads to the same final liquid saturation of 20% near the core outlet. However, upon increasing simultaneously the liquid and gas injection rates (at constant foam quality) the secondary desaturation is enhanced, resulting in a lower final liquid saturation. For the cores having a layering parallel to flow the secondary desaturation is relatively stronger but the final liquid saturation remains higher. A completely different fluid distribution is obtained for cores having a layering perpendicular to the flow direction due to a capillary entrapment phenomenon. The final liquid saturation far from core inlet is identical to that of homogeneous core. However, the pressure drop is considerably lower suggesting that foam flows under a coalescence regime.
Study on Characteristics and Development Law of Fractured Basement Reservoirs: A Case Study of Fractured Basement Reservoirs in Damintun Depression of Liaohe Basin
Authors: Shaosheng Chen , Kun Xu , Yun Han , Yuzhe Cui
Published: December 2007

The basement hydrocarbon reservoirs in Damintun Depression in Liaohe Basin mainly are fractured reservoirs. The hydrocarbon accumulation is closely related with fracture development. The basement fracture development is dominated by lithology and structure. In the paper, the basement fracture development regulations are disclosed by the methods such as palaeostructure stress field, fracture fractal geometry qualitative analysis, image logging and dip-angle logging interpretation and seismic multi-seismic attributes fracture identification. The fracture development zones are located near the faulting belts, crossing and complex positions of many faults, thrust structures and the turning point of the anticline structure. Fractured reservoirs are mainly developed in Mid-Proterozoic carbonate and quartzite; in Archaezoic granulite or magmatite; while the fractured reservoirs of argillaceous, schist and intrusive rock in that stage are less developed. Stratigraphic unconformities, are often the weathered crusts exposed on the earth for a long time, which undergo strong leaching and weathering for a long time resulting in well developed fractures and caves, where are the likely places for oil and gas accumulation in the basement fractured reservoir. The fractures are predicted and identified based on the fracture development regulations and seismic multi-attributes inversion.
Implementation of Advanced Acoustic Telemetry System Adds Value and Efficiency to Well Testing Operations
Authors: Harper George , Almanza Edgar , Fosså Arild , Finley Doug , Strang Gerry
Published: December 2007

In the past, in order to acquire real time, bottomhole SRO (surface read-out) data, either a downhole latching system or a download probe in close proximity to the transmitting device had to be used. An innovative SRO system that takes advantage of state-of-the-art developments in acoustic technologies, wireline, and wireless transmission, and yet, is compatible with tools conventionally used during drill stem test operations has now been introduced to the industry. This acoustic data-acquisition system provides access to real-time bottomhole data using either a wireline-deployed probe or via wireless acoustic signals sent through the production tubing. If the probe is used, this does not have to be close to the transmitting device in order to transfer the data to surface. Since the system offers the option of transmitting via wireline or via the wall of the testing pipe, the need for a probe or latching device along with the inherent problems that sometimes occur because the probe becomes stuck in the latch or mechanically fails can be eliminated. Finally, the additional rig time required for preparation and running of the probe to move the Acoustic Telemetry System (ATS) transmitter up to proper depth is saved, reducing operational costs.
Invert Emulsion Fluid System with Enhanced Rate of Biodegradation. Part 2
Authors: Durrieu Josiane , Benaissa Saddok , Clark David E. , Aubry Frederic
Published: December 2007

Research has been conducted to reduce the environmental impact of drill cutting discharge, when using a synthetic, ester, or mineral oil based fluid. The successful application of this technology will increase the biodegradation rate of the contaminant fluid, and reduce solids handling and treatment costs. The newly developed and optimized process utilizes organic nitrogen and phosphorus compounds and fatty acids to enhance the biodegradation rate of waste fluid. Previous work discussed the chemistry and laboratory test protocol used to develop this approach. The design criteria demanded that the drilling fluid maintain stable fluid properties and resistance to common contaminants encountered while drilling. It was also important in the design work to insure the resultant fluid did not damage return permeability and maintained reservoir integrity. The final formulations also could not increase the toxicity of the drilling fluid, as determined by standardized test protocols. The final approach has resulted in a more readily biodegradable system than currently available synthetic-based fluids.

Part two of this work demonstrated the effectiveness of the degradation booster fluid to increase aerobic and anaerobic biodegradation of several synthetic-base oils. Data collected from an isomerized olefin (IO) based biodegradation tests, Leptocheirus sediment toxicity and poly-nuclear aromatic hydrocarbons content clearly highlight the compliance of this novel invert fluid with regards to the Gulf of Mexico EPA protocol. This newly developed environmentally fluid can be applied not only offshore but in onshore sensitive areas.
Forms of Mercury in Drilling Fluid Barite and Their Fate in the Marine Environment: A Review and Synthesis
Authors: Trefry John H. , Smith J. P.
Published: December 2007

This paper reviews scientific information on chemical forms and fate in the marine environment of mercury associated with drilling fluid barite. Overall, the available evidence supports the conclusions that mercury associated with drilling-fluid barite: (1) is mainly present in metal sulfides with very low solubility, (2) is not detectably leached into seawater, and (3) has limited availability to marine organisms. Reported mercury concentrations in barite from diverse sources range from <0.05 - 31 µg/g. Mercury concentrations in drilling fluid barite are in the low end of this range and have an approximately lognormal distribution with a geometric mean concentration of 0.4 µg/g. High mercury concentrations in barite from vein deposits in contact with metal sulfides, and low levels of mercury in barite from sulfide-poor and carbonate-rich bedded deposits, suggest that mercury is present in barite in association with sulfide minerals. Chemical leaching experiments also are consistent with the presence of sulfide forms of mercury in barite, in that little or none of the mercury can be leached under mild conditions (10% acetic acid) and all of the Hg (and <1% of the barium) can be dissolved with strong acids (HCl or aqua regia). Experiments with mixing of barite with seawater showed that <1% of the Hg in barite was released to the water column. Less than 0.02% of the mercury in barite was leached at pH ranges comparable to those in digestive fluids. Direct exposure of fish, clams, sand worms and shrimp to mixtures of drilling fluid barite and sediment showed that no statistically significant uptake of Hg occurred in fish and that only small amounts of mercury (<0.2 µg/g dry wt.) were taken up by the other organisms, possibly in the form of barite particles in the digestive track rather than as Hg absorbed into tissue.
Energy from High–Water–Cut Waste Oil Emulsions—An Emerging Technology
Authors: Begell W. , Dolinsky A. , Kremnev V. , Shafeyeva Y. , Wojtanowicz A. K.
Published: December 2007

This paper reports on a novel technology for potential treatment and recycling of sloppy oil, marine oil spill froth, tank bottoms, waste sludge from gravity separations, production pit sludge, etc. The water content of such waste is too high for conventional combustion. Presently, this type of waste is subject to land disposal followed by lengthy bioremediation.

This technology, based on the transformation of pulse energy, known as PET technology, recovers the heating energy of oil fraction from the waste containing up to 50% by volume of water, without separating the oil from the water. The process involves the fine emulsification of the mixture using a specially designed micro-pulsation unit. The resulting emulsion is then combustible so that the waste can be converted into useful fuel. Reported are results from the R&D testing of the technology with waste slurries and a variety of water-cut values. The most efficient combustion would typically result below 20% water cut. For higher values of water cut, some slurries could still be converted to fuel, whereas others require further processing or disposal. The study also shows the effect of post-treatment particle size distribution on the heating value of the treated waste. It demonstrates that adjusting the pulsation unit to produce emulsions of desired content could control the process. Other data, presented in the paper, include combined effects of types of waste, percentage of water cut, oil grade, emulsion stability, and energy consumption and production.

PET has economic and environmental advantages over conventional techniques (biological treatment/gasification of waste fuels). The technology reduces pollution and generates energy, while reducing the amount of waste. There is no required energy input for additional heating or drying. There are also considerable savings in transportation and storage costs. In addition, up to two-thirds of existing liquid waste could be recycled as useful fuel.
Well Abandonment Using Highly Compressed Sodium Bentonite - An Australian Case Study
Authors: Clark Jason , Salsbury Barry
Published: December 2007

In 1999, in response to its escalating number of wells requiring abandonment, ChevronTexaco initiated research into the use of compressed sodium bentonite as an alternative to cement for permanent well plugging. The objective of this research was to identify a process to reduce plugging costs by at least 30% to encourage the expeditious abandonment of the growing back-log of wells. A subsidiary company, Benterra Corporation, was established to manage ChevronTexaco's research and subsequent implementation of any proposed new processes. Following pilot studies in California, Benterra has so far abandoned over 500 wells across the USA using highly compressed sodium bentonite, marketed as "ZoniteTM".

The Barrow Island oil field is located on an A-class nature reserve and is operated by ChevronTexaco Australia Pty Limited on behalf of Joint Venture Participants, Mobil Australia Resources Company Pty Limited and Santos Offshore Pty Limited. Approximately 100 wells have been identified as possible abandonment candidates on Barrow Island. The Zonite plugging process could reduce the cost to abandon these wells by up to 50%. With the close involvement of the Western Australian Department of Minerals and Petroleum Resources (DMPR), ChevronTexaco undertook a Zonite plugging trial in October 2002. This was the first application of Zonite outside the USA.

This paper discusses the Barrow Island trial and the potential environmental and economic benefits of future Zonite abandonments.
The Characterisation of Base Oil Recovered From the Low Temperature Thermal Desorption of Drill Cuttings
Authors: Wait S. T. , Thomas D.
Published: December 2007

Increasingly challenging environmental legislation around the world has led to the development of technologies for the treatment of oil based mud (OBM) contaminated drill cuttings. Operators in many countries are currently using low and high temperature indirect thermal desorption to remove the oil and water from drill cuttings, providing an opportunity to recycle the recovered oils.

Thermal desorption plants are capable of recovering a variety of base fluids, including diesel, low toxicity, synthetic and crude oil. Safety and environmental concerns have been raised in the UK and Norway regarding the suitability of re-using the recovered fluids in the mud system. Occupational health concerns, mainly due to the potential presence of toxic species, have been voiced. Other countries around the world, including Holland, Kazakhstan, Denmark, Nigeria, Colombia, Bolivia and Ecuador, amongst others, already routinely reuse oil recovered from thermal processes in new drilling fluids.

This paper presents detailed chemical and physical analysis on the quality of fluids recovered from a low temperature indirect thermal desorption process in the United Kingdom. Detailed examples of a Synthetic and a Low Toxicity fluid are presented, including the compound(s) responsible for the characteristic odour associated with recovered oils, and a method for their removal. The results demonstrate that low temperature thermal desorption does not crack the base oil or produce toxic by-products, and that the recovered fluid has suitable rheological and toxilogical properties for reuse in drilling fluids.
Innovative Website for Drilling Waste Management
Authors: Veil John A. , Gasper John R. , Puder Markus G. , Sullivan Robert G. , Richmond Pamela D. , Fidler Brandy R. , Fleming Carole N. , Bernier Rene F. , Jones Fredrick V.
Published: December 2007

Drilling waste management practices vary in different parts of the United States and elsewhere in the world. Those practices are governed by regulatory agencies charged with the protection of human health and the environment. Within the United States, regulations vary by state and address the environmental issues by geographic location. Regulations for offshore and international drilling waste management vary, as well. In a project funded by the U.S. Department of Energy, Argonne National Laboratory, in conjunction with Marathon and ChevronTexaco, is developing an interactive website to provide technical, unbiased information about drilling waste management options. The website will include components such as a technology description module to familiarize readers with available options, a regulatory module to summarize existing state and federal regulations governing drilling waste, a case study module to exhibit successful implementations of various technologies, and an interactive technology identification module to help users identify waste management options applicable in their region. This information system will provide operators with easy access to regulations, waste management options, technology, and cost data, thus allowing them to choose the option with the most environmental and economic benefits. Another benefit is that it will provide information to countries currently developing drilling waste regulations so that those regulations include the most economic, environmentally appropriate waste management options, not only options familiar in that country. The paper describes the design of the website and summarizes the data that are being collected to populate it.
Field Performance of Clutched Sucker Rod Pumping Systems
Authors: Guo Boyun , Zhang Morgan , Feng Jin
Published: December 2007

This paper reports the performance of a new type of overrunning clutch that has been developed and installed on sucker rod pumping units. The clutch disengages the power-input shaft of the gear reducer and the unit sheave whenever the torque on the shaft is negative. Based on the results of more than 100 installations, it was found that the pumping speed increased by 9% in average. Liquid production rate increased by up to 30%. Power saving was 23.6% on average. It was also observed that downhole sand and paraffin deposit problems were greatly alleviated. This paper presents pump performance analyses and clutch selection for sucker rod pumping systems.
Advanced Techniques for Acoustic Liquid-Level Determination
Authors: Rowlan O. Lynn , McCoy J. N. , Becker Dieter , Podio A. L.
Published: December 2007

Acoustic liquid level tests are performed successfully in many different applications throughout the world. Advanced techniques for acoustic liquid level analysis are required for wells where unusual conditions exist such as very shallow liquid levels, annular partial obstructions, flush pipe, short tubing joints, etc. Some wells have liners, upper perforations, paraffin, odd length of tubing joints, poor surface connections and other conditions which result in an acoustic trace that may be very difficult to interpret. Normally, the computer software locates the liquid level and automatically processes collar reflections to accurately count almost all of the collars from the initial blast to the liquid level. This automatic analysis will determine the liquid level depth for 95% of the wells. However, some wells have conditions or anomalies that these procedures will not function as desired. This paper describes special advanced techniques that can be used to determine the liquid level in wells with these unusual conditions.
Analysis of Stimulation Effectiveness in the Ammo Field Granite Wash Based on Reservoir Characterization & Completion Database
Authors: Strickland Bill D. , Purvis Don L. , Cox Stuart A. , Brinska John C. , Barree Robert D.
Published: December 2007

Maximizing production is a common challenge that haunts the oil industry more today than it ever has. Shrinking reserves, environmental concerns and higher costs means we have to be more aggressive and efficient at draining our reservoirs. Completion studies have proven to be a valuable tool in maximizing production, however these studies often fail to take into account significant reservoir variables. To help understand the Ammo (Ammunition) Field Granite Wash in Washita County, Oklahoma, a study was performed looking at well variables to characterize the reservoir as well as determine the most efficient completion strategy. In this way, the reservoir variables were able to be quantified so offset productions and treatments could be compared with a high degree of confidence.

This paper examines a data set of wells using data compiled from core data, reservoir geology, drilling, completion, and production records maintained by the oil company. Stimulation records from the service company were then added as well as formation and calculated fracture properties. Drawdown production analysis techniques and non-Darcy flow effects were modeled to gauge frac half-lengths. Graphical techniques were then utilized with reservoir and treatment data to identify trends and anomalies.
Optimum Matrix Acidizing Treatment Methodology for Wells Located in the Haoud Berkaoui Field, Algeria
Authors: Derradji M. M. , Tiab D. , Derradj N. , Berkat A.
Published: December 2007

The most common reason of formation damage is the drilling operations. Mud invasion is the major problem that affects well productivity in HAOUD BERKAOUI field. As the source of damage is known, different types of acid systems are proposed by service companies to improve the near wellbore formation permeability. Matrix acidizing treatment is successful and economic when either no excess volume or insufficient volume is used. The determination of acid volume is complicated and is generally based on field experience or using rules of thumb. Rules of thumb may not be convenient and always over estimate or underestimate the volume. Selection methods based on laboratory experiments, however, are more close to real estimates since they take into consideration the rock mineralogy.

In this study, laboratory tests are discussed and their results are shown to determine the mineralogy and formation characteristics of HAOUD BERKAOUI field. Acidizing tests of 4 different acids are conducted and discussed to select the optimum fluids. Visual observations of cores using SEM are also used as interpretation tools. Besides, optimum volume is predicted based on the laboratory acid response curves.

Laboratory test results show permeability improvement for 3 systems. However; one system proposed to treat injection wells gave mediocre results. Tests also show the risk of emulsion and/or precipitations for some acids. Acid system 3 with 6% HCl and 1.5% HF is found to be the optimal fluid to treat both injection and production wells. This system presents a good permeability improvement with less damaging precipitates and no risk of emulsion. Guidelines for acid volumes based on 6% HCl -1.5% HF acid are provided and could be used as a starting point in acidizing job design for HAOUDBERKAOUI field.
The Application of Low-Polymer Cross-Linked Fluid in the Mid-Continent Region
Authors: Parks John
Published: December 2007

The gel residues left behind in the pore spaces can significantly reduce the conductivity and effective propped fracture length of proppant packs placed in a formation.

Lower gel loadings have been utilized as a method to minimize polymer damage. This places less polymer into the formation but may also bring the treatment dangerously close to the lower limit of viscosity needed to transport proppant away from the wellbore and into the formation. This is significant in low perm gas wells where propped fracture length is the key to efficiently draining the reservoir. A carboxymethyl guar (CMG) polymer system is another means of reducing the amount of polymer we place into the formation. The CMG gives equivalent viscosity of a carboxymethyl hydrapropal guar (CMHPG) system with about half the polymer loading1. This system can be applied with the same computer controlled chemical pumps and precise metering devices being used for conventional fluid systems.

This paper will look at the application of the CMG system in the Mid-Continent area consisting of Arkansas, Oklahoma and the Texas Panhandle and compare the production results to offset wells.
Neural Network Training-Data Selection Using Memory-Reduced Cluster Analysis for Field Model Development
Authors: Chen Dingding , Quirein John , Wiener Jack , Grable Jeff , Smith Harry
Published: December 2007

This paper is related to neural network processing of near well bore geological logging data. The paper has been prepared to address the increased use and interest in artificial intelligence technologies in the interpretation of open-hole and/or casedhole formation evaluation data.

A typical neural network model is developed from a training well or wells where measurements are available. The model is tested on a validation well or wells before it is applied to a specific field /reservoir. Quite often models are developed with limited data: for example single well data should be retrained with multi well data to improve its scope and applicability. Unfortunately, some efforts to upgrade can result in choosing to use sub-optimal training algorithms because of the need to deal with an extensively increased data size. The consequence is a reduction in predictive accuracy. To improve accuracy, it is wise to have ways (1) remove faulty, redundant and insignificant data, (2) detect inconsistent data, (3) have the ability to "add", i.e., duplicate samples in key target zones.

This paper discusses how cluster analysis can be integrated with graphic visualization and fuzzy decision making to support training-data selection in field model development based on multiple well data. A case study using cased hole logging data from a pulsed neutron tool demonstrates the method and its application in predicting the response of open hole triple-combo logs (neutron porosity, formation density and deep resistivity).
The Performance of Pseudofunctions in the Upscaling Process
Authors: Azoug Youcef , Tiab Djebbar
Published: December 2007

To obtain a reliable characterization of complex reservoirs, geoscientists and petroleum engineers commonly build geologic or geostatistical reservoir models which contain more than a million grid cells. However, for flow simulation such a detailed description demands a great deal of information and processing time. Therefore, less complex models are usually preferred where the number of grid cells must be reduced by a factor of 10 or more. Such scaling up necessarily involves the loss of information that must be captured through upscaling porosity, permeability and the use of pseudofunctions. The main objective of this paper is to determine a general method for using pseudofunctions for upscaling multiphase flow in 3D anisotropic heterogeneous reservoirs with different capillary and gravity numbers and applying the method to a real field case "Hassi Messaoud Field - Algeria".

The performance of different types of pseudofunctions is evaluated under different capillary and gravity numbers, and upscaling levels. As a part of this research study a software package to calculate pseudofunctions has been developed. It includes: (1) the input option from ECLIPSE restart files (2) generates pseudo curves for three phase three-dimensional problems using Kyte and Berry, Pore Volume, Stone, and Transmissibility Weighted methods, and (3) generates output file format which can be read by ECLIPSE 100™. A variety of homogeneous fine grid models representing different flow regimes were considered in this study and the performance of several pseudofunction methods was compared. All the pseudo function methods succeeded in reproducing the fine grid watercut and maintained oil production for the capillary dominated, equilibrium, viscous dominated flows, however, for the gravity dominated flow they failed to match the fine grid curve exactly. Although this shortcoming of the pseudofunction curves gives better results than the rock curves.

Next in this study, the results of the waterflood of a heterogeneous 3-D model of HMD Zone 17 are presented. This real field model confirmed the homogeneous case results: for high flow rates the pseudofunctions can be applied successfully to upscale from fine to coarse grid simulation.
New Hydraulic Fracturing-Fluid Technology Increases Production in the Barnett Shale and Reduces Impact on the Environment
Authors: Parker Mark , Slabaugh Billy , Walters Harold , Hart Thomas , Walsh F. Howard Howard , Haley Will , Harper Joe , Weaver Jim
Published: December 2007

Hydraulic fracturing-fluid systems are used to create fractures in hydrocarbon-producing reservoirs and to transport proppant into the fracture to support it and provide optimum production increase. Many reservoirs in North America and the world would not be economical prospects without this technology. Currently, most systems use water-soluble polymers composed of guar or guar derivatives. Additional materials are used to optimize the fluid characteristics for the application and to degrade the water-soluble polymer, making the fluid easier to recover from the well before production. The recovered fluids cannot be used again and must be disposed of in a proper manner.

A new hydraulic fracturing-fluid system has been developed that can provide excellent performance during the fracturing process with post-fracture treatment-fluid recovery approaching 100%. This fluid has the added benefit of being reusable after it is recovered following the treatment and before production. The benefits of reusing the treatment fluid include the cost savings associated with recovery and reuse of chemicals, the cost savings from reduced water volume requirements for subsequent treatments, and the elimination of disposal costs. In addition, the total volume of chemicals required for fracturing operations is significantly less, reducing the demand on the environment.

Reuse of this fluid system requires field analysis of the returned fluid and treatment of the fluid to preserve and maintain it for future use. To achieve the best results from the recovery, preparations should be made to capture and store the fluid for subsequent treatments.

This paper presents the application of the fluid system and the concept for recycling and reuse. The results of eleven treatments in the Barnett Shale in the Fort Worth Basin using the new fluid system and the recycled fluid system are provided.