bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bioreactors for Natural Gas Desulfurization
Authors: Fidler B. R. , Sublette K. L. , Jenneman G. E. , Bala G. A. 
Published: December 2007

Abstract
Approximately half of the reserve gas in the U.S. is subquality, meaning it contains contaminants such as hydrogen sulfide (H2S) or carbon dioxide. One of the most common problems in the gas industry is the removal and disposal of H2S also known as natural gas desulfurization or sweetening of sour gas. Many traditional methods of H2S removal are costly, energy intensive, and potentially dangerous. Therefore, these methods may not be suitable for some gas-production sites. Biological oxidation offers a safe, energy efficient, and cost-effective method for natural gas desulfurization. This laboratory has investigated biological oxidation of H2S for some time and the current research focuses on bioreactors to treat ‘stranded’ natural gas. Preliminary data were previously presented at EPEC 20021; this paper includes new designs and experimental data. Bioreactors utilizing the immobilization matrices Bio-Sep® and Bio-Sep®S (sufide-sorbing version) inoculated with Thiobacillus denitrificans have been used to treat a gas stream containing 10,000 ppm H2S. The desired removal efficiency is greater than 99%. Stirred-tank reactors were operated with both matrices for 3 and 8 months at maximum gas flow rates of 130 and 72 mg H2S/h for the original and sulfide-sorbing beads respectively, with removal efficiencies near 99.9%. Phospholipid fatty acid (PLFA) analysis revealed cell densities on the order of 1010 cells/g of bead. Packed-bed reactors will also be operated with both matrices. Feasibility studies will be conducted for both types of reactors. This research is ongoing with the goal of developing an economical bioreactor to treat ‘stranded’ natural gas.
Evaluation of Marine Sediment Qualities and their Effect on the Marine Closed Bottle Test for Testing the Biodegradability of Synthetic Drilling Mud Base Fluids
Authors: Roberts D. J. , Rabke Stephen , Bernier Rene 
Published: December 2007

Abstract
Biodegradation testing is one of the compliance issues for using Synthetic-Based Drilling Fluid (SBF) technology for drilling oil and gas wells off the US coast. In order to address this issue, the US EPA incorporated a modified version of the standardized biodegradation procedure ISO 11734 as a regulatory limitation for SBF discharges. The test uses marine sediments spiked with the test fluids and incubated anaerobically in closed serum bottles. The production of gas (CO2 and CH4) from the sediment is used to monitor the progress of biodegradation. The source of marine sediment is a critical factor affecting the rate and extent of olefin SBF degradation. This paper describes laboratory studies that investigated the potential of several marine sediments from around the Gulf of Mexico coast to serve as inocula for the anaerobic biodegradation test. Sediment performance was evaluated against chemical, physical, and biological properties in order to identify key screening parameters for selection of sediment in this test. Increasing numbers of sulfate-reducing bacteria, methanogens, general anaerobes, and aerobic hydrocarbon degraders correlated well with increasing degradation rates. The research identified a sediment screening tool that would optimize conditions for fluid degradation and may help avoid costly test-control failures. A study designed to test the effect of sediment storage revealed that sediment could be stored for up to 14 months and still pass the control criteria.
OSPAR-Compliant Technologies for Managing Drilling-Fluid Lost-Circulation Events
Authors: Fang C. C. , Thaemlitz C. 
Published: December 2007

Abstract
In the oil and gas industry, loss of circulation while drilling is a common problem. Lost drilling fluids typically go into fractures induced by excessive mud pressures, into pre-existing open fractures, or into large openings with structural strength in the formation. Loss of circulation can be costly and difficult to control. Severe losses can disrupt drilling operations for days. A wide variety of materials have been used or proposed [for patents] in attempts to cure lost circulation.1-5
One of many lost-circulation materials (LCM) used by drilling fluid companies is a super absorbent polymer (SAP). Crosslinked polyacrylamides, polyacrylate, or a combination of both are examples. These SAPs can be used alone or in combinations with other LCM to stop the fluid loss.6-9 SAPs function as LCM by expanding many times in volume when they encounter the fluids downhole and stop the fluid loss by plugging the fractures in formation. These SAPs have shown excellent technical performance; however, they have poor biodegradability, often less than 5% in 28 days (Organization for Economic Co-Operation and Development [OECD 306] Test for Biodegradability in Sea Water). Consequently, there are strong demands from both the regulatory and economic perspectives to develop more environmental friendly LCM to be used offshore.
The ideal LCM for offshore should be formulated with seawater and pose little or no risk to the marine environment, so that after the job is completed, the used LCM can be disposed of overboard. To achieve these goals, research is needed to develop an environmentally acceptable alternative. In this paper we report the results using a biodegradable super absorbent alternative as LCM. Our efforts include studies to further understand the key roles of absorption rate, efficiency and particle size in LCM. Experiments focused on the performance of candidate materials over wide ranges of temperature, pH, and salinity, and also their biodegradation and toxicity performance.
Effect of Residual Oil on the Particle Deposition Profile in Deep-Bed Filtration During Produced Water Reinjection
Authors: Ali M. A. J. , Currie P. K. , Salman M. J. 
Published: December 2007

Abstract
An on-line linear X-ray apparatus has been used to examine deep bed filtration during water injection in Bentheimer sandstone core samples. The aim of this project was to investigate the effect of residual oil saturation on the deposition profile of suspended solids in the injected water, and to compare that with a previous study at fully brine saturated cores. Hematite particles were used as suspended solids in the brine. The X-ray apparatus was used to estimate the amount of deposited material at any time and distance along the core sample. Permeability decline as determined by the pressure change and chemical analysis of hematite concentration were used to confirm the X-ray analysis.
The effect of residual oil saturation was seen in most of the samples. The presence of oil caused greater apparent damage (reduction of permeability). It was also observed that there is rather deeper invasion at residual oil saturation than at fully brine saturation, and it was inferred from the X-ray measurements that the external filter cake is thicker.
Small Propped Fracture to Remove Near Wellbore Formation Damage: An Example From the Veslefrikk Field in the North Sea
Authors: Haugland T. , Berg E. , Tjomsland T. 
Published: December 2007

Abstract
Preventing scale precipitation is one of the main issues for maintaining well productivity on the Veslefrikk Field 1. An oil soluble scale inhibitor treatment was pumped that reduced the initial productivity index (PI) from 21 Sm3/d/bar to 3 Sm3/d/bar. Reperforation only restored some of the productivity (from 3 to 7 Sm3/d/bar) indicating deeper near wellbore damage. A small hydraulic fracture stimulation was then performed, creating a propped fracture with a half-length of approximately 6 m. The PI then increased to 30 Sm3/d/bar, a 43% increase from the initial value. The stimulation was performed under pressure through a 2 7/8" work string run on Rig Assist Snubbing (RAS) with pumps and blenders rigged on the pipe deck.
Mineralogy Driven Scale Inhibitor Squeeze Designs
Authors: Gdanski R. , Funkhouser G. P. 
Published: December 2007

Abstract
This paper will discuss several aspects of how formation mineralogy can affect treatment designs. The paper will show how the mineralogy can be used to create a first good estimate of the adsorption isotherm, which is normally the primary controlling mathematical function that describes how the scale inhibitor will return from the formation. This was accomplished by first determining the true equilibrium adsorption isotherms of an example scale inhibitor on various single minerals. Short-core tests are often used to determine whether issues of formation damage might be relevant. However, this paper will show that scale inhibitors, particularly at pH less than 5, are reactive with formation mineralogy and can lead to fluid conditions not achievable in short-core testing, and therefore not generally anticipated during the squeeze treatment. Consequently, short-core tests may not always be a reliable indication of damage potential. This paper will discuss how an evaluation of the formation mineralogy can lead to insight into ways to avoid many damage mechanisms unobservable in short-core testing.
Production Enhancement From Sand Management Philosophy: A Case Study From Statfjord and Gullfaks
Authors: Andrews J. , Kjørholt H. , Jøranson H. 
Published: December 2007

Abstract
Statfjord and Gullfaks are "Brown" fields operated by Statoil in the Tampen area of the North Sea. The production from these fields is characterized by large volumes of water and increasing sanding tendencies. The operator has for many years followed a strategy whereby sand produced with the wellstreams has been handled topsides prior to on-site disposal. The adoption of a sand management strategy has been crucial for prolonging economic reservoir development during tail production. By choosing to deal with sand topsides the operator has been able to pursue low cost slot replacement drilling where wells are completed without sand control equipment. The cased-hole functionality has facilitated multitarget drilling and is suited to selective production of each sand member through cheap plug/perf interventions.
Significant gains in production (acceleration) and reserves (IOR) have resulted from the pursuance of sand management in these fields. Examples of wells showing productivity improvements as a direct result of allowing intervals to produce sand are presented. In addition, production gains achieved from replacing choked back "sand free" production with "maximum acceptable sand rate" production are presented. Increased sand tolerance has also led to reserve increases in some wells as unproductive intervals that were previously sanded up have cleaned up and started to flow. It will be argued that this strategy negates many concerns with formation damage during well work because such damage is produced out with the sand and the wells clean up naturally.
The transient nature of sand production is discussed and the production gains observed in each field is presented. Such a strategy requires that the sand production is managed in a safe and controlled manner where the negative consequences of sand production are manageable and predictable. This paper will also discuss the improvements made in sand detection and on-line erosion mapping required to improve the sand tolerance of these facilities.
Certifying Reserves Certifiers: The Time Has Come
Authors: Harrell D. R. 
Published: December 2007

Abstract
The E&P industry is taking steps to educate, test and certify qualified petroleum geologists and engineers in the specialty practice of evaluating and estimating petroleum reserves. The primary benefit of the elective certification program would be to heighten understanding and upgrade competencies through a rigorous curriculum designed by experts in the field. A secondary benefit would be to help restore a loss of investor confidence in publicly reported reserves estimates. This loss occurred after several major reserves writedowns during the first quarter of 2004. Also, the self-administered program may head off current initiatives to make third-party reserves audits mandatory, creating an opportunity for industry to take the lead before government does.
For justification, one should look no further than the value of world proved reserves and lesser, yet very significant value of reserves reported to the U.S. Securities and Exchange Commission. At $35/bbl and $5/thousand cubic feet (Mcf), for example, which is significantly lower than fourth quarter 2004 prices, reserves owned by U.S. companies reported to the SEC and investors represent a total value of more than $2 trillion (U.S.). This is a mere 3 percent of worldwide reserves, which are reported in a variety of ways. Inarguably, these staggering values should be estimated in accordance with internationally accepted practices by highly competent evaluators. Evaluator certification is a step in that direction.
Engineers or geologists certified as specialists would be recognized by the administering organization as having advanced skill levels as well as substantial experience in accepted methods. Requirements for accreditation would include prescribed levels of education and special training, experience and job history, knowledge and scoring on certification exams.
Development and Field Application of a Shallow Perforation Shutoff System for HP/HT Oil Wells
Authors: van Eijden J. , Arkesteijn F. , van Batenburg D. , van Vliet J. 
Published: December 2007

Abstract
Water production in a oil field in Syria has increased significantly in recent years. As a result oil production is currently constrained by facilities throughput. PLT surveys combined with a reservoir study on the field showed that some layers still have high hydrocarbon saturation whilst others are already swept by water. Good-quality sands are not properly swept, probably due to poor connectivity in the reservoir. By shutting of the watered-out sands the high oil saturation un-swept sands can contribute to the production. However, no mechanical through tubing technologies are currently available, due to the high expansion ratio, the high differential pressure (up to 3000 psi) and the high temperature of 150 °C.
A new particle-gel has been developed for solving the above-described problem in a cost-effective manner. The particle-gel system is a further development of the previously published gel-cement system.1 The system may be placed via coiled tubing similar to a cement squeeze. The particles in the system will create a diverting filter cake resulting in a uniform and shallow placement of the gel of typically less than 1 inch. The gel used as make up water of the slurry will be squeezed into the matrix creating a shallow matrix shut off after it is set. Selective perforation of the hydrocarbon zones can re-establish the oil production. Additionally, the shut off zones can be re-opened later in the well's life when artificial lift has been installed.
The system showed superior shut off performance in the laboratory compared to normal cement squeeze techniques. In the first field application the system was tested in vertical oil well with a static bottomhole temperature of 146 °C. A total of 186 meters of perforations were squeezed of with the particle-gel in a single attempt. Post-job PLT data confirmed that the shut off was complete because the sealed zone showed no inflow.
Prediction of Skin in Openhole Sand Control Completions
Authors: Jones C. , Tollefsen M. , Somerville J. M. , Hutcheon R. 
Published: December 2007

Abstract
Formation damage in openhole sand control completions comes from a variety of sources. The drill in fluid filtrate can cause near wellbore permeability alteration and in the case of a gravel packed completion, leak off from the gravel pack slurry can increase the damage. Once the gravel is in place, poor filter cake clean up and pack damage can further increase the skin.
Careful design and execution of the gravel pack can result in a low skin. However there is one additional damage mechanism, which is impossible to avoid, that of permeability alteration by rock failure. There is a high probability that rock failure takes place at some stage in the life of an openhole sand control completion and the effect of rock failure on the skin depends on the change in permeability produced by failure and on the completion type.
An objective of this work was to measure the effect of rock failure on permeability for a weak sandstone.
A yield zone model was used to determine the depth of rock failure away from the wellbore and the effective stresses in the yield (failed) zone. The permeability changes were coupled with the yield zone model to predict the evolution of skin during depletion for a variety of completion options. Using the properties for the rocks tested, the model predicts for a compliantly expanded expandable sand screen completion an initially zero or slightly negative skin that increases slightly as depletion proceeds. For a non-compliant screen the model predicts a slightly higher initial skin, which again increases slightly with depletion. The predicted values are commensurate with observed skin values for openhole expandable sand screen completions.
Mud-Induced Formation Damage in Carbonate Reservoirs: Consequences on Productivity of Open-Hole Horizontal Wells
Authors: Al-Taq A. , Bazin B. , Ding D. , Egermann P. 
Published: December 2007

Abstract
An integrated approach including laboratory testing and numerical modeling was used in a study focused on mud-induced formation damage in carbonate open-hole horizontal wells, related to a field application in Saudi Arabia. This approach incorporates (1) evaluation of damage from laboratory flow experiments; (2) interpretation of flow testing results by two-phase flow modeling, and (3) integration of the physical data describing the formation damage into a numerical near-wellbore model for the evaluation of skin value and well productivity.
In the laboratory investigation, drilling and clean-up fluids were applied to two different reservoir core samples representing two classes of permeability. Two cleaning fluids were compared: a conventional mild acid wash and a new product system comprising a retarded acid and an enzyme breaker. Although laboratory testing is helpful for the selection of drilling and clean-up fluid, it cannot be directly used to evaluate well performance. Hence, a numerical model, which takes into account near-wellbore formation damage mechanism and laboratory testing data, is used to estimate potential productivity loss.
The modeling of the lab results shows that the heterogeneity of the cores has a determinant effect on the flow parameters (second drainage). This interpretation of the lab results is fundamental for the well modeling. Well productivity after drilling was evaluated with a dedicated software for Modeling Inflow Performance (MIP). The improvements brought by the new cleaning fluid were evaluated by both laboratory experiments and numerical simulations. The results obtained show comparable skin values between model prediction and field data.
Increase of Accuracy in Determination of Skin-Effect and Perm Thickness Product For Low Permeability Reservoirs
Authors: Diyashev R. N. , Iktissanov V. A. 
Published: December 2007

Abstract
Pressure build-up time upon shutting-in a well depends on filtration parameters of formation, increasing with their impairment. Therefore, incomplete pressure build-up curve for low permeability reservoirs frequently occurs. In this case the segment, offsetting by 1.5 of log cycle from derivative maximum, is not achieved. Interpretation of such pressure build-up curves, using known programs as Pansystem, Saphir, Fekete etc., leads to a significant error. This is confirmed by skin pressure drop with the absolute values considerably exceeding depression, as well as unreal flow efficiency.
In this connection, a method for interpretation of pressure build-up curve has been elaborated, allowing to increase accuracy in determination of formation and bottom-hole zone filtration parameters. This is achieved by combined consideration of wellbore storage and prehistory of filtration using numerical methods. In so doing, knowledge of initially unknown formation pressure and boundaries, on which it is maintained constant, is not required.
The method received wide practical approval for reservoirs with permeability of 0.1-300 mD. The results showed that actual value of perm thickness product, calculated by suggested method, is smaller then by well-known methods. The difference is increasing at short pressure build-up time and also for reservoirs with low perm thickness product. Therefore, the most effect from application of the suggested method is achieved while interpretation of pressure build-up curve with low perm thickness product. The method has also been used to estimate efficiency of different stimulation methods for wells, drilling-in and completion methods in Tatneft JSC fields. Results of interpretation allowed to give practical recommendations on selection of most efficient technologies.
An Experimental and Modeling Investigation of Acid-Created Channels in Sandstone
Authors: Xie T. , Li C. , Pournik M. , Zhu D. , Hill A. D. , DeVine C. 
Published: December 2007

Abstract
Wormholing is a common phenomenon in carbonate acidizing. These macro-sized channels, which are several orders of magnitude larger in diameter than natural pores, provide a magnified flow path, and hence enhance productivity. As the acid mainly attacks the larger pores, acid can penetrate much farther into the formation and bypass the formation damage rather than dissolve it. There is experimental evidence that wormholing on a smaller scale can occur in sandstone formations. The purpose of this study was to determine the treatment conditions and formation characteristics required for such wormholes to be created in sandstone through experimental and modeling work.
We have conducted extended experiments with samples of varying properties at different treatment conditions. Meanwhile, a theoretical model was built to simulate the process and visualize the acid etching pattern in the laboratory core samples. The findings from this study show that there are many parameters that affect the etching pattern. The most important factor that determines etching pattern is the heterogeneity of the rock sample. The spatial variation in permeability, porosity, and mineralogy are the driving force for the acid to channel through certain paths, developing highly permeable channels or wormholes in sandstone. The simulation results show that high permeability channels result when the initial porosity distribution is non-uniform, especially with existence of high porosity streaks. Such wormholes are not likely generated in homogenous rocks, even with an extremely high concentration HF acid solution at a high temperature. Uniform dissolution patterns are created in such samples as supported from our experimental work.
Effect of Natural Fractures on Hydraulic Fracture Propagation
Authors: Potluri N. , Zhu D. , Hill A. D. 
Published: December 2007

Abstract
Various fracture interaction criteria were reviewed and a systematic study is presented to analyze the effect of natural fractures on hydraulic fracture propagation. From the literature review, the approach of Warpinski and Teufel was adopted to evaluat the fracture propagation that would occur after a hydraulic fracture intersects an existing natural fracture. The study determined the conditions of differential stress, angle of intersection, and fracture toughness for which dilation of the natural fracture would occur. Criteria for the subsequent modes of fracture propagation are then presented.