bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Iron-Based, Environmentally Friendly Hydrogen Sulfide Scavenger for Drilling Fluids
Authors: Davidson E. , Hall J. , Temple C. 
Published: December 2007

Summary
A new scavenger has been developed that relies on the affinity between iron and sulfide. The active chemical is a form of ferrous iron complexed with a carbohydrate derivative. It is highly soluble in the brine phases of water-based mud (WBM) and will not precipitate at pH values greater than 12. When the iron is in solution, the reaction with sulfide is instantaneous and complete. This paper deals with the environmental implications of zinc vs. iron and the development of the new scavenger. It presents details of case histories concerning operations on a reservoir containing 25% hydrogen sulfide (H2S). Even in these demanding conditions, there was no H2S at surface.
Application of Lean Six Sigma in Oilfield Operations
Authors: Buell R. S. , Turnipseed S. P. 
Published: December 2007

Summary
This paper summarizes the experiences and results that improve business performance using Lean Six Sigma in North American and Asian upstream oil and gas operations. The background and history on Lean, Six Sigma, and Intl. Standardization Organization (ISO) systems are also provided. The role ISO-quality systems can play in supporting Lean and Six Sigma is explained and demonstrated with examples. The overviews of completed Lean Six Sigma projects are provided for well testing, rod-pump repair, water treatment, oil treatment, well stimulation, and production logging.
Modeling of Severe Slug and Slug Control With OLGA
Authors: Fard Mehrdad P. , Godhavn John-Morten , Sagatun Svein I. 
Published: December 2007

Summary
With the recent developments in the oil and gas industry, in which the number of satellite fields are increasing, the industry faces major challenges. A mixture of gas and oil is transported in multiphase pipelines along the bottom of the sea from the wells and up through the riser to the oil rig. The development of unstable flow in multiphase pipelines is a major and expensive problem. The irregular flow results in poor oil/water separation, limits the production capacity, and causes flaring. Handling slug flow thus has become very important with regard to increasing the production rate and avoiding possible equipment damages.
In this paper, we have developed a model of a physical process that generates slugs. The model has been verified against experimental data. Several control strategies have been tested on the model, and the simulation results are presented. It is shown by simulation of multiphase flow that the unstable slug flow can be stabilized by feedback control. In addition, interesting and important phenomena such as inverse response of the pressure at the top and asymmetric response of the pressure at the bottom have been revealed and explained.
Conditioning Truncated Gaussian Realizations to Static and Dynamic Data
Authors: Le Ravalec-Dupin Mickaële , Roggero Frédéric , Froidevaux Roland 
Published: December 2007

SummaryThe truncated Gaussian method is based on the transformation of continuous Gaussian realizations into discrete facies realizations. Each facies is associated to an interval that depends on its volume fraction. At a given location, the value of the continuous realization identifies an interval and, therefore, a facies. Within this context, the purpose of history matching is to produce facies realizations in agreement with the static facies observations and the measured dynamic data (pressures, water cuts, and flow rates). This problem is addressed through an optimization process: we minimize an objective function that measures the mismatch between the measured dynamic data and the corresponding simulated ones. During this iterative process, many truncated Gaussian realizations are investigated until we obtain the one that best reproduces the dynamic data. To account for the static data, all of the investigated truncated Gaussian realizations are constrained to the facies observations. This intermediate step is not as obvious as it seems. It requires the conversion of the facies observations to Gaussian values that respect both the spatial structure and the intervals characterizing the facies. Up to now, the algorithms that perform this conversion were very slow and were thus only used once during the optimization process. This constraint has a significant negative impact on the minimization of the objective function. We develop a new, and fast, conversion algorithm that turns facies observations into Gaussian values respecting the spatial structure and the intervals. In addition, it is well-suited for the gradual deformation algorithm. With the new proposed methodology, the converted Gaussian values can be gradually modified at the same time as the spatial distribution of the facies. This greatly speeds up the matching process. A numerical example is shown to compare the performance of the new matching approach with that of the conventional one.
Fracture Treatment Design and Execution in Low-Porosity Chalk Reservoirs
Authors: Cipolla C. L. , Hansen K. K. , Ginty W. R. 
Published: December 2007

SummaryThis paper details the results for 33 propped-fracture treatments in low-porosity zones in the South Arne (SA) field, Danish North Sea. To date, seven horizontal wells (2900 m total vertical depth [TVD]) have been completed using 100 tip screenout (TSO) propped-fracture treatments containing 70 million pounds of proppant. The target oil bearing Tor and Ekofisk intervals range from 40 to 120 m of combined thickness, with a Young's modulus and permeability that can vary from less than 0.5 to over 2.5 million psi and 0.1 to 4 m, respectively, along the horizontal section. The wide variations in reservoir and rock properties present significant fracture design and execution challenges.Results indicate that propped-fracture treatments become increasingly more difficult to place as porosity decreases, and this problem is primarily attributed to higher natural fracture/fissure density in the lower-porosity, higher-modulus zones. Production data indicate that these natural fractures or fissures do not measurably contribute to productivity, but can be "activated" under fracturing conditions. Contrary to intuition, pad size and fluid-loss additives must be increased and maximum proppant concentration decreased in low-porosity (low-permeability) zones. In the higherporosity, higher-permeability northern portion of the field, pad sizes of 35,000 gal containing 20,000 lb of 100-mesh sand allowed the placement of 800,000 lb of proppant at concentrations up to 15 pounds of proppant added per gallon of fluid (ppa). However, in the lower-porosity, lower permeability southern portion of the field, pad sizes of 200,000 gal containing more than 100,000 lb of 100-mesh sand were required to place similar proppant volumes, with concentrations limited to 8 ppa. This paper summarizes field data from 100 treatments, illustrating the design changes necessary to place propped-fracture treatments in low-porosity chalk reservoirs. The paper documents the relationship between chalk porosity, fluid efficiency, and treatment design.
A New Effective Stimulation Treatment for Long Horizontal Wells Drilled in Carbonate Reservoirs
Authors: Nasr-El-Din Hisham A. , Al-Habib Nabil S. , Al-Mumen Adib A. , Jemmali Mohammed , Samuel Mathew 
Published: December 2007

SummaryEffective matrix acidizing of horizontal and multilateral wells can be a highly challenging task. Unlike vertical wells, horizontal wells can extend several thousand feet into the formation. Reservoir heterogeneity and the length of the horizontal leg can make acid placement and diversion very difficult. In addition, the low drawdown encountered in horizontal wells results in longer times to lift the spent acid from the well, especially in tight formations.To achieve better acid diversion in horizontal wells drilled in carbonate reservoirs, a viscoelastic-surfactant-based system was used. The components of this new system are HCl and a viscoelastic surfactant. The acid dissolves calcite and dolomite minerals and produces calcium and magnesium chlorides. The increase in pH forces the surfactant molecules to form rod-shaped micelles. The produced chloride salts further stabilize these structures, especially at high temperatures. The rod-shaped micelles will significantly increase the viscosity of the acid, diverting the acid into tight, unstimulated, or severely damaged zones.More than 100 wells with openhole (OH) completions were successfully stimulated in two offshore oil fields in Saudi Arabia by use of the new acid system. With a water zone 30 ft away from these OH sections in one of the fields, growth of any dominant wormhole into these sections could increase water production. The wells that used the new treating fluid produced an average of 1,600 BOPD more than conventionally treated wells, with no indication of water production. Field results [pre- and post-oil and -water production rates and flowing wellhead pressure (FWHP)] demonstrate the effectiveness of the new acid system to matrix acidize long horizontal wells with OH completions. The simplicity of the system makes it the fluid of choice, especially in offshore and sour environments. The absence of metallic crosslinkers in this system eliminates problems associated with sulfide precipitation in sour wells.
Hot Oil and Gas Wells Can Be Stimulated Without Acids
Authors: Frenier Wayne , Brady Mark , Al-Harthy Salah , Arangath Roberto , Chan Keng Seng , Flamant Nicolas , Samuel Mathew 
Published: December 2007

SummaryA revolutionary family of treating fluids designed for the stimulation of critical, hot, or exotic oil and gas wells has been developed through application of detailed chemical and engineering studies.1–3 Formulations based on the hydroxethylaminocarboxylic acid (HACA) family of chelating agents have now been used to successfully increase production of oil and gas from wells in a variety of different formations. Included in the field test matrixes were new and producing wells drilled into carbonates and sandstone formations. The temperatures of the wells treated ranged from 230 to 370°F (110 to 187°C) bottomhole static temperature (BHST).Because these formulations do not contain high concentrations of corrosive mineral or organic acids (the formulations are less acidic than carbonated beverages), very low corrosion rates of the tubulars can be achieved by application of small amounts of special, inexpensive corrosion inhibitors. The mild fluids also are highly retarded so that high-temperature carbonates can be stimulated and sensitive sandstone formations are not damaged. The fluids have reduced health, safety, and environmental (HSE) footprints because:They are much less toxic to mammals as well as to aquatic organisms than mineral acids or organic acids such as hydrochloric (HCl), hydrofluoric (HF), or formic acid. The fluids are returned to the surface at pH values between 5 and 7, and they frequently can be added to normal well production fluids without neutralization. Because of much lower corrosion rates for corrosion resistant alloys (CRAs), lowered concentrations of Ni and Cr will be in the well returns compared with conventional acids that also may contain antimony (as a corrosion inhibitor).
Stabilized Productivity of a Hydraulically Fractured Well Producing at Constant Pressure
Authors: Hagoort Jacques 
Published: December 2007

Summary
This paper describes a simple and easy-to-construct numerical model for the calculation of the stabilized productivity of a hydraulically fractured well producing at a constant well pressure. The model takes into account both Darcy and non-Darcy pressure losses in the fracture. Dimensionless charts are presented that illustrate productivity improvement as a function of fracture length, fracture conductivity, and non-Darcy flow. For dimensionless fracture lengths in excess of 0.2, constant-pressure productivities are significantly lower than constant-rate productivities as predicted, for example, by the McGuire-Sikora productivity improvement chart. The maximum difference is 20% for an infinite-conductivity fracture with a length of unity. Both fracture conductivity and non-Darcy flow adversely affect well productivity; the reduction in productiv-ity is larger for longer fractures.
Effect of Water Cut on Sand Production—An Experimental Study
Authors: Wu Bailin , Tan Chee P. , Lu Ning 
Published: December 2007

Summary
It is commonly acknowledged in the petroleum industry that water cut increases sand-production risk, and a number of possible mechanisms have been proposed. This paper presents the results of a series of laboratory perforation-collapse tests aimed at demonstrating and quantifying the water-cut effect on perforation failure and sand production.
The laboratory perforation-collapse tests were conducted on weak sandstones obtained from downhole and outcrop. The tests were performed under simulated in-situ effective stresses and drawdown conditions. Water was introduced into the flowing stream of either oil or gas at various stages of the tests to simulate water cut. The failure and sand-production processes were observed and recorded using a borescope in real time.
The results showed that the effect of water cut on perforation strength and sand production depends on the mineralogical composition of the sandstone and the degree of residual water saturation. The effect is most significant for sandstones with high clay content and low residual water saturation and is less significant for clean sandtones or those with high residual water saturation. The experimental results are discussed on the basis of the chemical interaction between water and rocks—capillary stress and relative permeability. It is concluded that water-saturation-induced rock-strength reduction is the most significant factor governing perforation failure and sand production. Although perforation failure is a prerequisite for sand production, the failure does not always lead to sand production.
A Simple Model for Annular Two-Phase Flow in Wellbores
Authors: Hasan A. R. , Kabir C. S. 
Published: December 2007

Summary
Annular flow is associated with production from both gas-condensate and geothermal wells. Oil wells also experience it during high-gas-to-oil-ratio (high-GOR) production. The current semimechanistic modeling approach requires estimation of film thickness before computing frictional pressure drop as gas flows past the wavy-liquid film surrounding the pipe wall. This study intends to investigate this film thickness and its impact on pressure-drop computation in wellbores producing steam-water, gas-condensate, and gas-oil mixtures.
Computational results show that this dimensionless liquid-film thickness is most likely less than 0.06 in annular flow. For such values of thin-film thickness, the computed friction factor is only slightly higher than that estimated with a smooth-channel assumption. When the homogeneous model is used to compute pressure gradient by ignoring the wavy-liquid film on frictional pressure drop, good agreement is achieved with field data and with the predictions of a semimechanistic model.
A Laboratory Study With Field Data of Downhole Gas Separators
Authors: McCoy J. N. , Podio A. L. , Lisigurski Omar , Patterson John , Rowlan Lynn 
Published: December 2007

Summary
Downhole gas separators are often the most inefficient part of a sucker-rod pump system. This paper presents laboratory data on the performance of five different gas-separator designs. Only continuous flow was studied. Field data are presented on two of the designs. The field data indicate that success or failure of the gas separator is dependent upon the fluids and wellbore pressures as well as the mechanical design of the gas separator. Successful and unsuccessful examples of gas-separator performance in the field are shown along with field fluid data properties.
Application of Gas Lift Technology to a High-Water-Cut Heavy-Oil Reservoir in Intercampo Oilfield, Venezuela
Authors: Hong'en Dou , Yuwen Chang , Dandan Hu , Wenxin Cai , Guozhen Zhao 
Published: December 2007

Summary
This paper presents successful applications of gas lift technology to heavy-oil reservoirs in Intercampo oilfield, Lake Maracaibo, Venezuela. Liquid production rates range from 10 to 320 m3/day per well. Gas lift was selected as the first artificial lift method in the oilfield. The paper describes the gas lift mechanisms applied in a high-water-cut heavy-oil (below 15 API) reservoir. The theoretical analysis showed that the injection gas rate for gas lift and the gas/oil ratio (GOR) of an oil well have direct effects on the fluid flow from the wellbore.
Theoretical design and actual gas lift production are described in the paper. The correlations used for artificial gas lift design for high-water-cut heavy oil need to be refined to match the field data. The difference between theoretical design and actual production is significant for high-water-cut heavy oil lower than 15 API. Formation of oil/water emulsion was not observed during gas lifting of low-API, high-water-cut oil from wells.
In this study, a correction coefficient for gas lift design was applied to a high-water-cut, low-API field. Further work is needed to refine this gas lift design software. It should prove particularly useful for production engineers in optimizing the design of gas lifting equipment.
Controlling Formation Fines at Their Sources To Maintain Well Productivity
Authors: Nguyen P. D. , Weaver J. D. , Rickman R. D. , Dusterhoft R. G. , Parker M. A. 
Published: December 2007

Summary
Migration of formation fines has been shown to cause production decline in many wells. Despite the availability of new downhole tools for use in well stimulation and completion, the ability to sustain desired production levels is often plagued with fines migration problems. The solution to this problem is appropriate treatment to mitigate fines migration at its source. This paper describes the use of an ultra-thin tackifying agent (UTTA) for stabilizing fines in high-rate producing or injection wells. This UTTA is applied as part of an initial prepad in fracturing or gravel-packing operations, as a remedial treatment, or as a post-treatment following acid fracturing or matrix acidizing treatments. The primary purpose of UTTA application is to immobilize formation fines so that they will not detach, migrate with flowing fluids, plug the pore channels, and reduce the flow path permeability.
Results of laboratory testing indicate that the UTTA system is applicable to most types of formation fines, including coals, sandstones, and carbonates. Once injected into the formation matrix or proppant pack, the UTTA forms a thin film on formation surfaces, encapsulating the fines. Capillary action helps pull the tackifier into the contact points, fixing the particulate in place without plugging the pore throat. The UTTA does not require a shut-in time after its application. The thin film tackifier does not harden, but remains flexible, enhancing the ability of a formation to withstand stress cycling and allowing the formation to handle high shear stress during high flow rates.
Gas Storage and Operations in Single-Bedded Salt Caverns: Stability Analyses
Authors: Han Gang , Bruno Mike , Lao Khang , Young Jean , Dorfmann Luis 
Published: December 2007

Summary
Bedded salt formations are located throughout the U.S., providing valuable storage capacity for natural gas and other hydrocarbons. To increase gas-storage capabilities and provide operators with improved geotechnical design and operating guidelines for these caverns, stability analyses of single-bedded salt caverns have been completed and are described in this paper. This work is a part of integrated efforts initiated and sponsored by the U.S. Department of Energy (DOE), the Gas Technology Institute (GTI), and Pipeline Research Council International, Inc.
Numerical geomechanical models have been developed to investigate single-cavern deformation and bedding-plane slip for a variety of cavern configurations. A viscoplastic salt model has been developed based on an empirical creep law developed for the Waste Isolation Pilot Plant (WIPP) Program and combined with a Drucker-Prager model for damage and failure. The nonsalt materials are described with either a traditional Mohr-Coulomb model, or an elastic model, depending on layer properties.
A baseline model with specified geometric dimensions is first selected and subjected to 1-year cyclic pressure operations. The amount of damage around the cavern wall and roof is evaluated and used as a comparison in the study. Then, the operations are extended to 15 years to study cavern stability for long-term gas storage and operations. In addition to the baseline model, parametric studies have been performed to investigate cavern damage as a function of salt roof thickness, overburden stiffness, interface properties, and cavern geometries. Each cavern simulation includes 1 year of pressure cycling with a minimum, mean, and maximum cavern pressure of 6.1 MPa (884.5 psi), 8.8 MPa (1,276 psi) and 14.9 MPa (2,160.5 psi), respectively. Different operation conditions (e.g., hydrostatic, cyclic, and direct-pressure drawdown) are compared and evaluated in terms of cavern stability.
These analyses can be a basis to selecting the best salt cavern candidate for gas storage and operations as well as helping to assess critical cavern design parameters for thin-bedded salt formations.
The Repression of IRS2 Gene by ATF3, a Stress-Inducible Gene, Contributes to Pancreatic β-Cell Apoptosis
Authors: Li Dan , Yin Xin , Zmuda Erik J. , Wolford Christopher C. , Dong Xiaocheng , White Morris F. , Hai Tsonwin 
Published: December 2007

OBJECTIVE—β-Cell failure is an essential component of all types of diabetes, and the insulin receptor substrate 2 (IRS2) branch of signaling plays a key role in β-cell survival and function. We tested the hypothesis that activating transcription factor 3 (ATF3), a stress-inducible proapoptotic gene, downregulates the expression of IRS2 in β-cells.
RESEARCH DESIGN AND METHODS—We used both the gain- and loss-of-function approaches to test the effects of ATF3 on IRS2 gene expression. We also analyzed the binding of ATF3 to the IRS2 promoter by chromatin immunoprecipitation assay and the transcription of the IRS2 gene by polymerase II occupancy assay. Furthermore, we tested the ability of IRS2 to alleviate the proapoptotic effects of ATF3 in cultured β-cells and in transgenic mice using the rat insulin promoter to drive the transgenes.
RESULTS—Expression of ATF3 is sufficient to reduce IRS2 gene expression; in contrast, knockdown or knockout of ATF3 reduces the ability of stress signals to downregulate IRS2 expression. ATF3 binds to the IRS2 promoter in vivo, and the binding of ATF3 correlates with decreased IRS2 gene transcription. Functionally, expression of IRS2 protects β-cells from ATF3-induced apoptosis.
CONCLUSIONS—IRS2 is a target gene of ATF3, and its repression by ATF3 contributes, at least partly, to the apoptosis induced by ATF3. Because ATF3 is a stress-inducible gene, our work provides a direct link to explain how environmental stress factors can modulate IRS2 gene transcription.