bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adult Coho Salmon and Steelhead Use of Boulder Weirs in Southwest Oregon Streams
Authors: Roni Phil , Van Slyke Dan , Miller Bruce A. , Ebersole Joseph L. , Pess George 
Published: June 2008

Abstract
The placement of log and boulder structures in streams is a common and often effective technique for improving juvenile salmonid rearing habitat and increasing fish densities. Less frequently examined has been the use of these structures by adult salmonids. In 2004, spawner densities and redd counts of coho salmon Oncorhynchus kisutch in seven Oregon streams were compared between 10 reach pairs: reaches with artificially placed boulder weir structures (treatment) and reaches without weirs (control). In addition, based on annual spawner survey data collected from 2001 to 2005, redd density of steelhead O. mykiss and spawner and redd densities of coho salmon were examined to assess differences among main-stem reaches with boulder weirs, main-stem reaches without weirs, and tributary reaches without weirs throughout one basin (West Fork of the Smith River (WFS)). Numbers of coho salmon spawners and peak redd counts were significantly higher (P ≤ 0.05) in treatment reaches than in control reaches in the first study. In contrast, no differences existed in coho salmon spawner counts or steelhead redd counts among reaches within WFS. Coho salmon redd densities differed significantly among the three reach types in WFS; redd densities in tributary reaches were higher than those in main-stem reaches either with or without boulder weirs. Both spawner density and redd density were positively correlated with percent gravel. Results from these two related studies suggest that the placement of boulder weirs in bedrock channels leads to localized increases in spawner abundance, although other factors (e.g., amount of spawning area or gravel) appear to influence coho salmon and steelhead spawner abundance and redd construction at a watershed scale. This also suggests that gravel sources are an important factor to consider when placing boulder weirs or other instream structures designed to improve spawning habitat.
Carbon Sources for Lake Sturgeon in Lake Winnebago, Wisconsin
Authors: Stelzer Robert S. , Drecktrah H. Gene , Shupryt Michael P. , Bruch Ronald M. 
Published: June 2008

AbstractBecause lake sturgeon Acipenser fulvescens, like other sturgeon species, are threatened or endangered in many aquatic ecosystems, it is imperative that we increase our understanding of their role in food webs. Our main objective was to determine the carbon sources for lake sturgeon in Lake Winnebago, Wisconsin, which contains one of the largest populations of lake sturgeon in North America. Gut content analysis revealed that gizzard shad Dorosoma cepedianum and Chironomus plumosus larvae (56% and 33% by gut content mass, respectively) were the primary prey items for lake sturgeon in the winter. Larger lake sturgeon were more piscivorous than smaller individuals. A mixing model using δ13C and δ15N suggests that Chironomus contributes 49% and gizzard shad 37% to the carbon assimilated by lake sturgeon. We estimated the carbon half‐life in lake sturgeon to be about 0.6‐3.0 years based on a model incorporating metabolism and growth. Thus, the stable isotope results integrate over a considerably longer time period than the gut content analysis. Our results provide critical baseline information about the carbon sources for lake sturgeon that can be used to assess how their role in food webs may change after perturbations such as the introduction of exotic species and changes in land use.
Optimizing Horizontal Completions in the Cleveland Tight Gas Sand
Authors: Samuelson M. L. , Akinwande T. , Connell R. , Grossman R. , Strickland B. 
Published: June 2008

Abstract
This paper describes an efficient multistage horizontal openhole completion technique as an alternative to conventional openhole or cemented and perforated lateral completions. The application focuses on openhole (OH) completions in the Cleveland tight gas sand of the Texas panhandle. Horizontal wells have been drilled extensively in this low permeability gas reservoir to enhance productivity.(5) While the increased contact area offers a potential for enhancing well productivity and overall well economics, additional stimulation is usually required. Conventional OH or cemented and perforated completion alternatives have had various operational and logistic issues that have minimized efficiency and production impact. The system applied involves the use of a series of mechanical openhole packers deployed on the production liner with a frac port located between each set of packers and a process of subsequent multistage stimulation of the entire interval. The multistage OH completions have resulted in better connection to the reservoir compared to conventional cased-hole staged completions. Significantly increased completion efficiencies have been realized in all areas of the Cleveland tight gas sand, resulting in reduced completion costs and reduced overall completion timeframes.
Investigation of Underground Gas Storage in a Partially Depleted Gas Reservoir
Authors: Azin Reza , Nasiri Amir , Entezari Ali Jodeyri , Montazeri Gholam Hossein 
Published: June 2008

AbstractUnderground Gas Storage (UGS) is a means of installing peak shaving capacity during high-demand seasons worldwide. In this work, studies of the UGS were performed on a partially depleted gas reservoir through compositional simulation. Prediction of reservoir fluid phase behavior and history match was done by utilizing detailed reservoir information. The performance of UGS with different scenarios of reservoir depletion, gas injection, and aquifer strength was analyzed. The injection capacity and deliverability of reservoir was set to 350 MMSCF/D (6 months) and 420 MMSCF/D (5 months), respectively. Based on different scenarios and the anticipated target rate, the optimum pressure for converting this reservoir to UGS was found to be about 1600 psia. Also, it was found that if the reservoir is depleted to a lower pressure, it contains insufficient base gas reserve and may not meet the target withdrawal rate. It was found that this problem can be overcome by injecting higher volume of gas in the first cycle. Furthermore, simulation studies showed that an active aquifer can lead to irreversible reservoir shrinkage, increase in water-gas ratio, and pressure rise in reservoir. Another source of pressure rise during the UGS operations is the difference between z-factors of injected and reservoir fluids. It was found that injecting lean gas with high z-factor into a reservoir containing fluid of lower z-factor results in pressure rise at the end of each cycle. At successive cycles, composition of reservoir fluid approaches that of the injected gas because of continual mixing. Theoretically, composition of reservoir fluid will approach to the injected fluid after infinite cycles, provided complete mixing occurs in reservoir. Under these conditions, difference between z-factors of injected and reservoir fluids become smaller, and reservoir pressure stabilizes.
Discussion on Dynamic Reserves Estimation of Multilayer Gas Reservoir With Material Balance Method
Authors: Hedong Sun , Yujin Wan , Shimin Zhong , Liangren Liu 
Published: June 2008

Abstract
In recent years, more and more multilayer gas reservoirs were discovered in the world. Forecasting the dynamic reserve of multilayer producer is a major challenge for reservoir engineering. Material Balance Equation (p/z plot) is one of the fundamental methods for reserve estimation. It is usually used in single layer gas reservoir.
In this paper, the applicability of multilayer gas reservoir material balance equation for reserve estimation is studied by single well numerical simulation. There are several parameters which influence reserve estimation of multilayer gas reservoir, such as the connectivity between layers of gas reservoir, the difference between formation pressures of the layers, the difference between permeability of the layers.
Results of numerical simulation show that vertical permeability is the main factor that influences reserve estimation. Reserve estimation has a large accuracy when vertical permeability is larger than 1E-4mD. Reserve estimation value tends to be smaller than the true value when the vertical permeability is smaller than 1E-4mD, and the more non-homogeneous layer, the larger the deviation is.
The results of numerical simulation show that difference between the permeability of the layers is another main factor in reserve estimation. For a larger non-homogeneity between layers, calculated dynamic reserve decreases as increase of non-homogeneity between layers, and the dynamic reserve of the layer with low permeability is low.
The Use of Reinforced Thermoplastic Pipe in Oil and Gas Gathering and Produced Water Pipelines
Authors: Conley J. , Weller B. , Slingerland E. 
Published: June 2008

Abstract
Reinforced thermoplastic pipe (RTP) is an alternative to traditional pipelining materials. It consists of three basic layers including a thermoplastic liner, helically wrapped continuous high-strength fiber reinforcement and an external thermoplastic jacket. The liner acts as a bladder, the fiber reinforcements provide strength, and the jacket protects the load-bearing fibers. Applications include oil and gas gathering and produced water transfer.
A study was conducted to verify the operational performance of RTP. This study consisted of testing and inspection of cut-out samples of previously operated RTP to determine if any significant level or form of degradation had occurred as a result of normal operation.
Thirty samples of Flexpipe Line Pipe (FPLP) RTP were cut out from different pipelines for inspection and testing. The service fluids included gas, oil emulsion and produced water in both sweet and sour service. The operating pressures ranged from 51 psi to 720 psi and the operating temperatures ranged from 37°F to 104°F. The duration of operation prior to the removal of the samples ranged from twelve to forty-one months.
The average burst pressure after service was found to be 99.7% of the average burst pressure measured at the time of manufacture. Dissection and inspection of the liner of the cut-out samples found no signs of blistering, swelling, cracking or collapse. The fiber reinforcements did not display any signs of discoloring, fraying, breaks, cuts, buckling, reorientation or other damage. The jacket was free of cracks, penetrations and ballooning. Tensile testing of fiber reinforcement and liner material from four of the cut-out samples found that the material properties remained close to typical values measured at the time of manufacture.
The test results demonstrate that FPLP RTP did not degrade after being exposed to a wide range of normal gas, oil emulsion, and produced water applications with operation durations ranging from twelve to forty-one months. This finding supports the results of the qualification testing that has been performed on this product in accordance with API RP 15S and CSA Z662-07.
Optimizing Glycol Dehydration System for Maximum Efficiency: A Case Study of a Gas Plant in Nigeria
Authors: Arubi I. M. T. , Duru U. I. 
Published: June 2008

Abstract
In optimizing glycol dehydration system for natural gas, several critical parameters exist, which can be varied to achieve, a specified dew point depression. This paper studies the effect of varying the glycol flow rate, number of stages or height of the packing column in the contactor, re-boiler temperature, and striping gas rate on the glycol dehydration unit of a gas plant in Nigeria using HYSYS. Process simulator.
An HYSYS model of the plant was developed and used to investigate the important design parameters. The results were then used to provide an analysis of the dehydration effectiveness at a variety of common operating variables. Emissions control in the glycol regenerator and the flash tank were also presented.
The investigation revealed that the design of the triethylene glycol (TEG) system is adequate to condition the gas to achieve a water dew point of 5°C at 95bar. However, either the lean glycol cooler operation is not optimized or that it is undersized for the duty it is currently subjected to.
In today's competitive economy, the Engineer must become as productive as possible. One means of increasing this productivity is to use process simulation packages. Hence this paper seeks to proffer solution options for optimizing the gas plant dehydration process using HYSYS.
Examples of Fractured Carbonate Reservoir Rocks of Russia, and Relationship Between Porosity and Permeability in Carbonate Rocks
Authors: Chilingar George V. , Haroun Muhammad R. , Bagrintseva K. I. 
Published: June 2008

Abstract
New methodology (cubic cores) of studying fractured carbonate reservoirs is presented in this paper. Several examples of Russian carbonate reservoirs are given including: Orenburg Gas-Condensate Field, Urmansk Oilfield and Vuktyl'skiy Gas-Condensate Field.
A correlation between porosity and permeability was established, which is of vital importance in carbonate reservoir rock characterization.
On considering two additional variables (irreducible fluidI saturation and specific surface area, which is a measure of degree of fracturing), very good correlation was obtained between porosity and permeability. Without considering these two variables, the coefficient of correlation is commonly very low.
The authors believe that the century-old problem of correlation between porosity and permeability of carbonate rocks has been finally solved. Similar studies should be carried out elsewhere, for example, Asmari Limestone of Middle East.
Developing Tight Gas Sand Adviser for Completion and Stimulation in Tight Gas Sand Reservoirs Worldwide
Authors: Holditch S. A. , Bogatchev K. Y. 
Published: June 2008

AbstractAs the demand for energy worldwide increases, the oil and gas industry will need to increase recovery from unconventional gas reservoirs (UGR). To economically produce UGRs, one must have adequate product price and one must use the most current technology. Tight Gas Sands (TGS) contribute three quarters to the total U.S. gas production from UGRs. TGS reservoirs require stimulation as a part of the completion, so improvement of completion practices is very important. We did a thorough literature review to extract knowledge and experience about completion and stimulation technologies used in TGS reservoirs. We developed the principal design and two modules of a computer program called Tight Gas Sand Advisor (TGS Advisor), which can be used to assist engineers in making decisions while completing and stimulating TGS reservoirs. The modules include Perforation Selection and Proppant Selection. Based on input well/reservoir parameters these subroutines provide unambiguous recommendations concerning which perforation strategy(s) and what proppant(s) are applicable for a given well. The most crucial parameters from completion best-practices analyses and consultations with experts are built into TGS Advisor's logic, which mimics human expert's decision-making process. TGS Advisor's recommended procedures for successful completions will facilitate TGS development and improve economical performance of TGS reservoirs.
Initial Surveillance in the Cannonball Field: Design, Implementation, and Interpretation
Authors: Jemmott Susan T. , Baksh Kirk , Jones Jack 
Published: June 2008

Abstract
The Cannonball West gas and condensate field is located in the Columbus basin, 35–40 miles off the southeast coast of Trinidad in water depths of 240 feet. It is comprised of a single reservoir unit, the TP65 sand, situated at 12,334 ft. true vertical depth subsea. This field was discovered in 2002 by the exploration well, Ironhorse-1 ST1, which penetrated the reservoir down dip of the Sparrow fault block, and just south of the adjacent Red Mango accumulation. The sand was initially over pressured at 6,400 psi; with a temperature of 220 °F. The volumetric estimate of gas in place was 1 trillion cubic feet of gas.
This reservoir was developed with three vertical wells, completed as open-hole gravel-packs with 7 5/8" production strings. The well design was based on parameters estimated from the discovery well and a target per-well production rate of 280 million standard cubic feet of gas. Each well was successfully instrumented with permanent downhole pressure and temperature sensors as well as wellhead, casing, pre-and post-choke pressure and temperature sensors, well-by-well ‘wet’ gas rate meters and well flowline acoustic sand detectors. All of this data is available real-time and is continuous.
Field startup followed in early 2006. Hydrocarbons are produced via a dedicated normally unmanned platform. This platform is Trinidad's first locally fabricated platform, and is a 9-slot installation with a production capacity of 1 billion cubic feet per day. Fluids flow through a 26″ subsea pipeline to the nearby Cassia B central hub for processing prior to sale to local industry and LNG facilities. The operation is managed by bp Trinidad and Tobago, plc. (bpTT).
To quantify completion efficiency, well-by-well drainage areas and connected volumes, and to garner data to help set safe nominally sand-free operating limits, a baseline surveillance program was designed prior to initial production. The purpose of this paper is to detail the design, implementation and interpretation of this baseline testing program. In particular, we show how the design reconciled the need for extended, high quality pressure buildup data with the need to maintain a reliable gas supply, one of bpTT's core reputation values. We also delineate how the test design incorporated multiple datasets allowing redundant, independent calculation of key parameters. Finally, we show how individual well completion condition, drainage area and connected volume were quantified and how the combined results fit within and tie to the seismic interpretation. Implications for inter-well connectivity along with future operations and drilling are discussed in the closing section of the paper.
The Optimal Hydraulic Fracture Geometry Under Non-Darcy Flow Effects
Authors: Zeng Fanhua , Zhao Gang 
Published: June 2008

Abstract
The presence of non-Darcy flow in the hydraulic fracture significantly reduces the effective conductivity of the fracture, and hence adversely affects the productivity of a hydraulically fractured gas well. It has been disclosed that under non-Darcy flow effect a shorter and wider fracture geometry provides better productivity than a longer and narrower fracture; on the contrary, for Darcy flow a longer and narrower fracture yields higher productivity.
This work is to optimize hydraulic fracture geometry under non-Darcy flow effects in hydraulic fractured well in order to obtain maximum well productivity and economic benefit. A rigorous mathematical model is established to describe transient non-Darcy flow in hydraulic fractures and coupled with Darcy fluid flow in the reservoir. A semi-analytical method is further presented to solve this model. Then, on the basis of the simulation results, the fracture geometry is optimized for two goals. The first goal is to obtain the maximum well productivity under a given fracture volume. On the basis of theoretical analysis and hundreds of simulation results, a semi-experiential correlation is developed to calculate the optimal fracture length. The equation generated suggests that the optimal fracture length is proportional to (1/β)1/3, which means that if non-Darcy flow increases 8 times, the optimal fracture length would have been decreased by half. The optimal fracture length is also a function of fracture volume, formation permeability, fluid viscosity and density, net pay thickness and flow rate. The second goal is to achieve the maximum economic profit through optimizing the fracture volume, since larger fracture volume generally brings larger productivity, and also leads to higher hydraulic fracturing cost. Analyses show that the severer the non-Darcy flow, the smaller the optimal fracture volume required. Therefore, fracture geometry optimization should involve two stages: fracture volume optimization and fracture length optimization.
The proposed optimal fracture length equation had been applied to analyze several cases from the literature. The results show that the design criterion to eliminate the non-Darcy flow effects will cause such a short fracture length that the well productivity would be reduced significantly. Therefore, it is suggested that well productivity and economical benefit should be systematically considered being the design criterion in hydraulic fracturing stimulation.
The Study and Application of Low-Damage and Massive Hydraulic Fracturing Technique in Tight Gas Formations With High Temperature and High Pressure
Authors: Qun Lei , Jiang Tingxue , Yun Xu , Ding Yunhong , Lu Yongjun , Bo Cai , Shu Yuhua , Duan Yaoyao 
Published: June 2008

Abstract
There are a lot of tight gas formations with high temperature and high pressure in the south of Songliao basin in northeast China. However, it is very difficult to conduct successful fracturing treatment jobs as results of deep wells (more than 4200 m), high temperature (more than 150°C) and high pressure (more than 60 MPa), etc. Therefore, a systematic studies have been performed to overcome above mentioned difficulties, and the highlights are: 1) Fine formation evaluations prior to fracturing treatment; 2) A new finely processed Guar is developed, and the concentration is only 0.45% for the temperature of 150°C, and residue content 125 mg/l correspondingly, both are much less than those of commonly used Guar system; 3) Smaller sized proppant with high strength is optimized, sometimes, more than two proppant types or sizes is also chosen comprehensively; 4) Fuzzy undetermined analysis of economic benefit is performed to optimize propped fracture length and conductivity, in which the Monte-Carlo method is utilized; 5) Many fracturing treatment parameters are changed and combined optimizedly such as proppant's type and size, fracturing fluid's type, cross linked ratio, concentration of based fluid, concentration of gel breaking agent, and pumping rate as well, which makes it not only to ensure the successful treatment but also to minimize fracture damage so as to maximize fracturing treatment potential; 6) Spiral mode of proppant pumping schedule is put forward in order to prevent earlier screen-out; 7) A new forced fracture closure technique is utilized to improve propped profile in the case of multiple payzones. Above low damage and massive fracturing technique was put in to filed applications in 6 gas wells, all treatments were completely successful with the maximal proppant weight being as high as 165,000 kg, while in the past, there were many treatment failures. And the highest post-fracturing rate 70,000 m3/d, which is satisfied as expected. So, it has a great significance not only in improving fracturing treatment effect in above mentioned gas formations but also in perfecting low damage and massive hydraulic fracturing technique as well.