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Expansion analyses of strategic petroleum reserve in Bayou Choctaw : revised locations.

Description: This report summarizes a series of three-dimensional simulations for the Bayou Choctaw Strategic Petroleum Reserve. The U.S. Department of Energy plans to leach two new caverns and convert one of the existing caverns within the Bayou Choctaw salt dome to expand its petroleum reserve storage capacity. An existing finite element mesh from previous analyses is modified by changing the locations of two caverns. The structural integrity of the three expansion caverns and the interaction between all the caverns in the dome are investigated. The impacts of the expansion on underground creep closure, surface subsidence, infrastructure, and well integrity are quantified. Two scenarios were used for the duration and timing of workover conditions where wellhead pressures are temporarily reduced to atmospheric pressure. The three expansion caverns are predicted to be structurally stable against tensile failure for both scenarios. Dilatant failure is not expected within the vicinity of the expansion caverns. Damage to surface structures is not predicted and there is not a marked increase in surface strains due to the presence of the three expansion caverns. The wells into the caverns should not undergo yield. The results show that from a structural viewpoint, the locations of the two newly proposed expansion caverns are acceptable, and all three expansion caverns can be safely constructed and operated.
Date: November 1, 2010
Creator: Ehgartner, Brian L. & Park, Byoung Yoon
Partner: UNT Libraries Government Documents Department

Special Conditions for HGP-A Wellhead Generator Proof-of-Feasibility Project, Specification S-00-001

Description: This specification applies to the general requirements of all purchased materials and equipment and provides general instructions for Suppliers. Purchaser as referred to here under is the Research Corp. of University of Hawaii. Rogers Engineering Co., Inc. is the authorized representative of the Research Corp. of University of Hawaii with respect to purchases made under this specification.
Date: October 25, 1978
Partner: UNT Libraries Government Documents Department

Pressure drawdown analysis for the Travale 22 well

Description: This work presents preliminary results on the analysis of drawdown data for Travale 22. Both wellhead pressure and flow rate data were recorded in this well for over a period of almost two years. In the past, Barelli et al. (1975) and Atkinson et al. (1977) presented the analysis of five pressure buildup tests. Figure 1 shows the Horner plot for these cases. They found that to have a good match in all cases, it was necessary to assume that the Travale 22 well is intersected by a partially penetrating vertical fracture in a parallel-piped whose bottom side is maintained at constant pressure (boiling front), as shown in Fig. 2. Atkinson et al. also presented an analysis for a pressure interface test run in the Travale-Radicondoli area. In this case, the Travale 22 well was flowing and the pressure recorded at wells R1, R3, R5, R6, R9, and Chl (see Fig. 3 ) . Analysis of these data showed that pressure interference in this reservoir can be matched by considering pure linear flow (Figs. 4 and 5 ) . This indicated the possible presence of a vertical fracture intersecting the Travale 22 well. It was determined that fracture is oriented along the N73{sup o}W direction. In addition, the pressure interference data showed that no boundary exists within 2 kilometers from the fracture plane. It was mentioned that linear flow should take place in both horizontal and vertical directions.
Date: January 1, 1978
Creator: Barelli, A.; Brigham, W.E.; Cinco, H.; Economides, M.; Miller, F.G.; Ramey, H.J., Jr. et al.
Partner: UNT Libraries Government Documents Department

Final Report to the Subsurface Science Program - Impact of Measurement Instrument and Conceptual Model on Analysis of Subsurface Heterogeneity

Description: This final report covers results of research initially focused on particle transport and then extended to study of measurement scale and scaling. Experimental, numerical, and theoretical findings were published in the areas of hydraulics in heterogeneous media, particle-chemical-microbial transport in heterogeneous media, sampling design, stochastics and wellhead protection. This work has resulted in 17 journal publications, a number of conference presentations, two Ph.D. dissertations, two Master's theses, and two manuscripts upon which undergraduate students have been co-authors.
Date: January 10, 2003
Creator: Silliman, Stephen E.
Partner: UNT Libraries Government Documents Department

DESIGN AND DEVELOPMENT OF INTEGRATED COMPACT MULTIPHASE SEPARATION SYSTEM (CMSS)

Description: The petroleum industry has relied in the past mainly on conventional vessel-type separators, which are bulky, heavy and expensive, to process wellhead production of oil-water-gas flow. Economic and operational pressures continue to force the petroleum industry to seek less expensive and more efficient separation alternatives in the form of compact separators. The compact dimensions, smaller footprint and lower weight of compact separators have a potential for cost savings to the industry, especially in offshore and subsea applications. Also, compact separators reduce the inventory of hydrocarbons significantly, which is critical for environmental and safety considerations. This report presents a brief overview of the activities and tasks accomplished during the part July 09, 2003--October 08, 2004, related to the Budget Period I (July 09, 2003--October 08, 2004) of the DOE project titled ''Design and Development of Integrated Compact Multiphase Separation System (CMSS{copyright})''. An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with discussions. The findings of this investigation are summarized in the ''Conclusions'' section followed by relevant references. The initial phase of the project (Budget Period I--07/09/2003 to 10/08/2004) focuses on the development of additional individual compact separation components, such as the horizontal pipe separator (HPS{copyright}), for obtaining clean oil stream from oil-water mixture, flow conditioning components, such as the helical pipe (HP) and slug damper (SD{copyright}), for dissipating slugs upstream of the compact separators. The project will also design and test an upstream slug generator (SG).
Date: December 31, 2004
Creator: Mohan, Ram S. & Shoham, Ovadia
Partner: UNT Libraries Government Documents Department

Pressure Profiles in Two-Phase Geothermal Wells: Comparison of Field Data and Model Calculations

Description: Increased confidence in the predictive power of two-phase correlations is a vital part of wellbore deliverability and deposition studies for geothermal wells. Previously, the Orkiszewski (1967) set of correlations has been recommended by many investigators to analyze geothermal wellbore performance. In this study, we use measured flowing pressure profile data from ten geothermal wells around the world, covering a wide range of flowrate, fluid enthalpy, wellhead pressure and well depth. We compare measured and calculated pressure profiles using the Orkiszewski (1967) correlations.
Date: January 21, 1986
Creator: Ambastha, A.K. & Gudmundsson, J.S.
Partner: UNT Libraries Government Documents Department

Design and Development of Integrated Compact Multiphase Separation System (CMSS)

Description: The petroleum industry has relied in the past mainly on conventional vessel-type separators, which are bulky, heavy and expensive, to process wellhead production of oil-water-gas flow. Economic and operational pressures continue to force the petroleum industry to seek less expensive and more efficient separation alternatives in the form of compact separators. The compact dimensions, smaller footprint and lower weight of compact separators have a potential for cost savings to the industry, especially in offshore and subsea applications. Also, compact separators reduce the inventory of hydrocarbons significantly, which is critical for environmental This report presents a brief overview of the activities and tasks accomplished during the Budget Period II (October 09, 2004-April 30, 2006) of the DOE project titled ''Design and Development of Integrated Compact Multiphase Separation System (CMSS{copyright})''. An executive summary is presented initially followed by the tasks of the current budget period. Then, detailed description of the experimental and modeling investigations are presented. Subsequently, the technical and scientific results of the activities of this project period are presented with discussions. The findings of this investigation are summarized in the ''Conclusions'' section In this investigation, the concept of CMSS{copyright} has been developed and is proven through simulation studies and validated by experimental data. As part of the second phase of the project (Budget Period II--10/09/2004-04/30/2006) experimental investigation of the integrated CMSS{copyright} for different configurations has been conducted in order to evaluate the performance of the individual separation components, and determine how they will affect the performance of each other when integrated in the CMSS{copyright}. An intelligent control system is also developed to improve the total system efficiency of Compact Multiphase Separation System (CMSS{copyright}). In mature oil fields, water handling poses a huge problem. Thus water knock out at the earliest stage helps in significant cost savings during handling, separation and ...
Date: April 30, 2006
Creator: Mohan, Ram S. & Shoham, Ovadia
Partner: UNT Libraries Government Documents Department

Putting downward pressure on natural gas prices: The impact of renewable energy and energy efficiency

Description: Increased deployment of renewable energy (RE) and energy efficiency (EE) is expected to reduce natural gas demand and in turn place downward pressure on gas prices. A number of recent modeling studies include an evaluation of this effect. Based on data compiled from those studies summarized in this paper, each 1% reduction in national natural gas demand appears likely to lead to a long-term average wellhead gas price reduction of 0.75% to 2.5%, with some studies predicting even more sizable reductions. Reductions in wellhead prices will reduce wholesale and retail electricity rates, and will also reduce residential, commercial, and industrial gas bills. We further find that many of these studies appear to represent the potential impact of RE and EE on natural gas prices within the bounds of current knowledge, but that current knowledge of how to estimate this effect is extremely limited. While more research is therefore needed, existing studies suggest that it is not unreasonable to expect that any increase in consumer electricity costs attributable to RE and/or EE deployment may be substantially offset by the corresponding reduction in delivered natural gas prices. This effect represents a wealth transfer (from natural gas producers to consumers) rather than a net gain in social welfare, and is therefore not a standard motivation for policy intervention on economic grounds. Reducing gas prices and thereby redistributing wealth may still be of importance in policy circles, however, and may be viewed in those circles as a positive ancillary effect of RE and EE deployment.
Date: May 20, 2004
Creator: Wiser, Ryan; Bolinger, Mark & St. Clair, Matthew
Partner: UNT Libraries Government Documents Department

Natural Gas Prices Forecast Comparison--AEO vs. Natural Gas Markets

Description: This paper evaluates the accuracy of two methods to forecast natural gas prices: using the Energy Information Administration's ''Annual Energy Outlook'' forecasted price (AEO) and the ''Henry Hub'' compared to U.S. Wellhead futures price. A statistical analysis is performed to determine the relative accuracy of the two measures in the recent past. A statistical analysis suggests that the Henry Hub futures price provides a more accurate average forecast of natural gas prices than the AEO. For example, the Henry Hub futures price underestimated the natural gas price by 35 cents per thousand cubic feet (11.5 percent) between 1996 and 2003 and the AEO underestimated by 71 cents per thousand cubic feet (23.4 percent). Upon closer inspection, a liner regression analysis reveals that two distinct time periods exist, the period between 1996 to 1999 and the period between 2000 to 2003. For the time period between 1996 to 1999, AEO showed a weak negative correlation (R-square = 0.19) between forecast price by actual U.S. Wellhead natural gas price versus the Henry Hub with a weak positive correlation (R-square = 0.20) between forecasted price and U.S. Wellhead natural gas price. During the time period between 2000 to 2003, AEO shows a moderate positive correlation (R-square = 0.37) between forecasted natural gas price and U.S. Wellhead natural gas price versus the Henry Hub that show a moderate positive correlation (R-square = 0.36) between forecast price and U.S. Wellhead natural gas price. These results suggest that agencies forecasting natural gas prices should consider incorporating the Henry Hub natural gas futures price into their forecasting models along with the AEO forecast. Our analysis is very preliminary and is based on a very small data set. Naturally the results of the analysis may change, as more data is made available.
Date: February 9, 2005
Creator: Wong-Parodi, Gabrielle; Lekov, Alex & Dale, Larry
Partner: UNT Libraries Government Documents Department

HGP-A Wellhead Generator, Proof-Of-Feasibility Project 3 MW Wellhead Generator, Start-Up Training and Operating Manual

Description: The start-up manual is an information aid to initially familiarize plant operators with the plant operation and later be used as a reference manual while operating the plant. This start-up manual is supplemented by the Plant Data Manual which contains a detailed description of the philosophy of operation and equipment characteristics. The sequencing herein presents the necessary operating procedures which must be followed in order that a smooth start-up is obtained. The sequence includes, first conditioning the well and stabilizing the steam/water separations, and then bringing the operating machinery on line. The Piping and Instrumentation Diagrams and Electrical Drawings are included under Section 12.0 and are frequently referred to in the text. Information for ''trouble-shooting'' is provided in the maintenance and operations manuals on all the equipment.
Date: January 1, 1981
Partner: UNT Libraries Government Documents Department

A Method to Recover Useful Geothermal-Reservoir Parameters from Production Characteristic Curves (1) Steam Reservoirs

Description: In this paper we develop and demonstrate a method to estimate the reservoir pressure and a productivity index for vertical steam wells, from its production characteristic (also called output) curves. In addition, the method allows to estimate the radius of influence of the well, provided that a value of the reservoir transmisivity is available. The basic structure of the present method is: first, the measured well head mass flowrates and pressures are transformed to downhole conditions by means of a numerical simulator; then, the computed downhole variables are fitted to a simple radial model that predicts the sandface flowrate in terms of the flowing pressure. For demonstration, the method was applied to several steam wells from the Los Azufres Geothermal field. We found excellent agreement of the model with this ample set of field data. As a bonus, the processed data allowed several inferences about the steam producing zone of the reservoir: that the wells considered produce from relatively isolated pockets of steam, which are probably fed by near-by inmobile water; and that these feed zones are in poor hydraulic communication with the field surface waters. our method are that it provides a way to retrieve important reservoir information from usually available production characteristic curves, and that the method works from easily and accurately taken wellhead measurements.
Date: December 15, 1983
Creator: Iglesias, E.; Arellano, V.; Garfias, A.; Miranda, C.; Hernandez, J. & Gonzalez, J.
Partner: UNT Libraries Government Documents Department

A Method to Recover Useful Geothermal-Reservoir Parameters from Production Characteristic Curves (2) Hot Water Reservoirs

Description: In this paper we develop and demonstrate a method to estimate the reservoir pressure, a mass productivity index, and a thermal power productivity index for vertical water-fed geothermal wells, from its production characteristic (also called output) curves. In addition, the method allows to estimate the radius of influence of the well, provided that a value of the reservoir transmisivity is available. The basic structure of the present method is: first, the measured wellhead mass flowrate; and pressures are transformed to downhole conditions by means of a numerical simulator; then, the computed downhole variables are fitted to a simple radial model that predicts the sandface flowrate in terms of the flowing pressure. For demonstration, the method was applied to several wells from the Cerro Prieto geothermal field. We found very good agreement of the model with this ample set of field data. The main advantages of our method are that it provides a way to retrieve important reservoir information from usually available production characteristic curves, that it works from easily and accurately taken wellhead measurements, and that its results address the two main aspects of geothermal resource utilization, namely, mass and heat production.
Date: December 15, 1983
Creator: Iglesias, E.; Arellano, V. & Molinar, R.
Partner: UNT Libraries Government Documents Department

Integrated Geothermal Well Testing: Test Objectives and Facilities

Description: A new and highly integrated geothermal well test program was designed for three geothermal operators in the US (MCR, RGI and Mapco Geothermal). This program required the design, construction and operation of new well test facilities. The main objectives of the test program and facilities are to investigate the critical potential and worst problems associated with the well and produced fluids in a period of approximately 30 days. Field and laboratory investigations are required to determine and quantify the problems of fluid production, utilization and reinjection. The facilities are designed to handle a flow rate from a geothermal well of one million pounds per hour at a wellhead temperature of approximately 268 C (515 F). The facilities will handle an entire spectrum of temperature and rate conditions up to these limits. All pertinent conditions for future fluid exploitations can be duplicated with these facilities, thus providing critical information at the very early stages of field development. The new well test facilities have been used to test high temperature, liquid-dominated geothermal wells in the Imperial Valley of California. The test facilities still have some problems which should be solvable. The accomplishments of this new and highly integrated geothermal well test program are described in this paper.
Date: January 1, 1981
Creator: Nicholson, R. W. & Vetter, O. J.
Partner: UNT Libraries Government Documents Department

Coalbed Methane Procduced Water Treatment Using Gas Hydrate Formation at the Wellhead

Description: Water associated with coalbed methane (CBM) production is a significant and costly process waste stream, and economic treatment and/or disposal of this water is often the key to successful and profitable CBM development. In the past decade, advances have been made in the treatment of CBM produced water. However, produced water generally must be transported in some fashion to a centralized treatment and/or disposal facility. The cost of transporting this water, whether through the development of a water distribution system or by truck, is often greater than the cost of treatment or disposal. To address this economic issue, BC Technologies (BCT), in collaboration with Oak Ridge National Laboratory (ORNL) and International Petroleum Environmental Consortium (IPEC), proposed developing a mechanical unit that could be used to treat CBM produced water by forming gas hydrates at the wellhead. This process involves creating a gas hydrate, washing it and then disassociating hydrate into water and gas molecules. The application of this technology results in three process streams: purified water, brine, and gas. The purified water can be discharged or reused for a variety of beneficial purposes and the smaller brine can be disposed of using conventional strategies. The overall objectives of this research are to develop a new treatment method for produced water where it could be purified directly at the wellhead, to determine the effectiveness of hydrate formation for the treatment of produced water with proof of concept laboratory experiments, to design a prototype-scale injector and test it in the laboratory under realistic wellhead conditions, and to demonstrate the technology under field conditions. By treating the water on-site, producers could substantially reduce their surface handling costs and economically remove impurities to a quality that would support beneficial use. Batch bench-scale experiments of the hydrate formation process and research conducted at ORNL confirmed ...
Date: December 30, 2009
Creator: Technologies, BC
Partner: UNT Libraries Government Documents Department

Geothermal Resources Development - HGP-A Wellhead Generator Proof of Feasibility Project

Description: Project: A 3 MW plant with single flash steam system. Totally enclosed plant building integrated with a visitors' center, within a fully developed site. Location: Puna District, Island of Hawaii. Construction Cost: US $8,000,000. Completed: Schedule completion August 1980. (This plant was officially dedicated, July 17, 1981 and is currently delivering energy to HELCO Power System in Hawaii. HELCO is operating this plant for the University of Hawaii). Services: Concept studies, preliminary design, final design, procurement and construction management.
Date: August 1, 1980
Partner: UNT Libraries Government Documents Department

Three dimensional simulation for bayou choctaw strategic petroleum reserve (SPR).

Description: Three dimensional finite element analyses were performed to evaluate the structural integrity of the caverns located at the Bayou Choctaw (BC) site which is considered a candidate for expansion. Fifteen active and nine abandoned caverns exist at BC, with a total cavern volume of some 164 MMB. A 3D model allowing control of each cavern individually was constructed because the location and depth of caverns and the date of excavation are irregular. The total cavern volume has practical interest, as this void space affects total creep closure in the BC salt mass. Operations including both cavern workover, where wellhead pressures are temporarily reduced to atmospheric, and cavern enlargement due to leaching during oil drawdowns that use water to displace the oil from the caverns, were modeled to account for as many as the five future oil drawdowns in the six SPR caverns. The impacts on cavern stability, underground creep closure, surface subsidence, infrastructure, and well integrity were quantified.
Date: December 1, 2006
Creator: Ehgartner, Brian L.; Park, Byoung Yoon & Lee, Moo Yul
Partner: UNT Libraries Government Documents Department

Thermal extraction analysis of five Los Azufres production wells

Description: Thermal energy extraction from five wells supplying 5-MWe wellhead generators in three zones of the Los Azufres geothermal field has been examined from production and chemical data compiled over 14-years of operation. The data, as annual means, are useful in observing small-scale changes in reservoir performance with continuous production. The chemical components are chloride for quality control and the geothermometer elements for reservoir temperatures. The flowrate and fluid enthalpy data are used to calculate the thermal extraction rates. Integration of these data provides an estimate of the total energy extracted from the zone surrounding the well. The combined production and chemical geothermometer data are used to model the produced fluid as coming from just-penetrating wells for which the annual produced mass originates from a series of concentric hemispheric shells moving out into the reservoir. Estimates are made of the drawdown distance into the reservoir and the far-field conditions.
Date: January 26, 1995
Creator: Kruger, Paul & Quijano, Luis
Partner: UNT Libraries Government Documents Department

Customized Well Test Methods for a Non-Customary Geothermal Well

Description: Recent testing of Thermal 4, The Geysers blowout well, has shown that the flow has two different components: a low enthalpy, mineral-laden flow from a well drilled within the existing wellhead and a high flowrate, high enthalpy annular flow. The commingled flows were mechanically separated and individually tested. The results of the test show that the flows are from two very different sources that are in weak hydraulic communication. Work is in progress to apply this information to bring Thermal 4 within compliance of the 1986 air quality regulations.
Date: January 21, 1986
Creator: Burr, Myron
Partner: UNT Libraries Government Documents Department

Worldwide Geothermal Power Plants: Status as of June 1980

Description: There are 100 geothermal power units now in operation throughout 12 countries, with a total installed capacity of just over 2110 MW. The average unit thus is rated at 21.1 MW. Newer units may be broadly classified as follows: (a) wellhead units of less than 5 MW; (b) small plants of about 10 MW; (c) medium plants of 30-35 MW; (d) large plants of about 55 MW; and (e) complexes typically consisting of several 55 MW units in a large geothermal field. There is a trend toward turbine units of the double-flow type with a 55 MW rating, used either alone or in a tandem-compound arrangement giving 110 MW in a single power house. This is particularly evident at The Geysers field in California. Double-flash units (separated-steam followed by a surface flash) are suited to high quality reservoirs having high temperature, high steam fractions at the wellhead, and low scaling potential. Single-flash units (separated steam) may be called for where scaling by the spent brine is a potential problem for the liquid disposal system. Binary plants are being used for some very low temperature reservoirs, particularly in the People's Republic of China, albeit in extremely small units. A large-scale pilot plant of the binary type is being planned for the Imperial Valley of California.
Date: December 1, 1980
Creator: DiPippo, Ronald
Partner: UNT Libraries Government Documents Department

Formation plugging while testing a steam well at The Geysers

Description: During testing of a steam well at The Geysers steam field in Sonoma County, California, rate suddenly dropped by 17,500 lb/hr and wellhead pressure simultaneously increased by 30 psi. There was no evidence of plugging in any of the surface facilities downstream of the wellhead. Pressure buildup tests before and after the incident show that there was a 15% reduction in permeability-thickness. Analysis of pressure losses in the wellbore due to friction showed that all of the rise in wellhead pressure could be explained by the reduction in mass flow that occurred as a result of the 15% reduction in kh. The change in wellhead enthalpy from 1200 Btu/lb and 4-5 F superheat prior to the incident to 1197 Btu/lb and 0-1.4 F superheat after the incident indicates the well became slightly wet. One possible explanation for this reduction in kh is that movement of free water caused a plugging action or a reduction of mobility to steam in one or more steam entries.
Date: January 1, 1978
Creator: Strobel, Calvin J.
Partner: UNT Libraries Government Documents Department

Thermochemically Driven Gas-Dynamic Fracturing (TDGF)

Description: This report concerns efforts to increase oil well productivity and efficiency via a method of heating the oil-bearing rock of the well, a technique known as Thermochemical Gas-Dynamic Fracturing (TGDF). The technique uses either a chemical reaction or a combustion event to raise the temperature of the rock of the well, thereby increasing oil velocity, and oil pumping rate. Such technology has shown promise for future application to both older wellheads and also new sites. The need for such technologies in the oil extraction field, along with the merits of the TGDF technology is examined in Chapter 1. The theoretical basis underpinning applications of TGDF is explained in Chapter 2. It is shown that productivity of depleted well can be increased by one order of magnitude after heating a reservoir region of radius 15-20 m around the well by 100 degrees 1-2 times per year. Two variants of thermal stimulation are considered: uniform heating and optimal temperature distribution in the formation region around the perforation zone. It is demonstrated that the well productivity attained by using equal amounts of thermal energy is higher by a factor of 3 to 4 in the case of optimal temperature distribution as compared to uniform distribution. Following this theoretical basis, two practical approaches to applying TDGF are considered. Chapter 3 looks at the use of chemical intiators to raise the rock temperature in the well via an exothermic chemical reaction. The requirements for such a delivery device are discussed, and several novel fuel-oxidizing mixtures (FOM) are investigated in conditions simulating those at oil-extracting depths. Such FOM mixtures, particularly ones containing nitric acid and a chemical initiator, are shown to dramatically increase the temperature of the oil-bearing rock, and thus the productivity of the well. Such tests are substantiated by preliminary fieldwork in Russian oil ...
Date: December 31, 2008
Creator: Goodwin, Michael
Partner: UNT Libraries Government Documents Department

Analysis of cavern stability at the Bryan Mound SPR site.

Description: This report presents computational analyses that simulate the structural response of caverns at the Strategic Petroleum Reserve Bryan Mound site. The cavern field comprises 20 caverns. Five caverns (1, 2, 4, and 5; 3 was later plugged and abandoned) were acquired from industry and have unusual shapes and a history dating back to 1946. The other 16 caverns (101-116) were leached according to SPR standards in the mid-1980s and have tall cylindrical shapes. The history of the caverns and their shapes are simulated in a 3-D geomechanics model of the site that predicts deformations, strains, and stresses. Future leaching scenarios due to oil drawdowns using fresh water are also simulated by increasing the volume of the caverns. Cavern pressures are varied in the model to capture operational practices in the field. The results of the finite element model are interpreted to provide information on the current and future status of subsidence, well integrity, and cavern stability. The most significant result in this report is relevant to caverns 1, 2, and 5. The caverns have non-cylindrical shapes and have potential regions where the surrounding salt may be damaged during workover procedures. During a workover the normal cavern operating pressure is lowered to service a well. At this point the wellhead pressures are atmospheric. When the workover is complete, the cavern is repressurized. The resulting elastic stresses are sufficient to cause tension and large deviatoric stresses at several locations. With time, these stresses relax to a compressive state due to salt creep. However, the potential for salt damage and fracturing exists. The analyses predict tensile stresses at locations with sharp-edges in the wall geometry, or in the case of cavern 5, in the neck region between the upper and lower lobes of the cavern. The effects do not appear to be large-scale, ...
Date: April 1, 2009
Creator: Ehgartner, Brian L. & Sobolik, Steven Ronald
Partner: UNT Libraries Government Documents Department