759 Matching Results

Search Results

Advanced search parameters have been applied.

Breakthrough Time for the Source-Sink Well Doublet

Description: A pressure transient analysis method is presented for interpreting breakthrough time between two constant rate wells. The wells are modeled as two line source wells in an infinite reservoir. The first well injects at a constant rate and the second well produces at a constant rate. We studied the effects of transient pressure conditions on breakthrough time. The first arrival of injected fluid at the production well may be significantly longer under transient condition than under steady state condition. A correlation of the deviation of the breakthrough time for transient pressure conditions from the steady state condition is presented.
Date: January 21, 1986
Creator: Menninger, Will & Sageev, Abraham
Partner: UNT Libraries Government Documents Department

Laboratory measurement of sorption in porous media

Description: A new apparatus for measuring steam adsorption-desorption isothermally on rock samples has been installed and initial runs made for rock samples from geothermal reservoirs. The amounts adsorbed measured in these experiments are the same order of magnitude as previous experiments.
Date: January 1, 1992
Creator: Harr, M. S.; Pettit, P. & Ramey, J. J., Jr.
Partner: UNT Libraries Government Documents Department

Modeling of geochemical interactions between acidic and neutral fluids in the Onikobe Geothermal Reservoir

Description: Two types of fluids are encountered in the Onikobe geothermal reservoir, one is neutral and the other is acidic (pH=3). It is hypothesized that acidic fluid might be upwelling along a fault zone and that an impermeable barrier might be present between the acidic and neutral fluid zones. We carried out reactive geothermal transport simulations using TOUGHREACT (Xu and Pruess, 1998 and 2001) to test such a conceptual model. One-dimensional models were used to study the geochemical behavior due to mixing of the two fluids. Mn-rich smectite precipitated near the mixing front and is likely to form an impermeable barrier between regions with acidic and neutral fluids.
Date: January 10, 2003
Creator: Todaka, Norifumi; Akasaka, Chitoshi; Xu, Tianfu & Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Increasing Waterflood Reserves in the Wilmington Oil Field Through Improved Reservoir Characterization and Reservoir Management

Description: The objectives of this quarterly report are to summarize the work conducted under each task during the reporting period October - December 1997 and to report all technical data and findings as specified in the "Federal Assistance Reporting Checklist". The main objective of this project is the transfer of technologies, methodologies, and findings developed and applied in this project to other operators of Slope and Basin Clastic Reservoirs. This project will study methods to identify sands with high remaining oil saturation and to recomplete existing wells using advanced completion technology. The identification of the sands with high remaining oil saturation will be accomplished by developing a deterministic three dimensional (3-D) geologic model and by using a state of the art reservoir management computer software. The wells identified by the geologic and reservoir engineering work as having the best potential will be logged with cased-hole logging tools. The application of the logging tools will be optimized in the lab by developing a rock-log model. This rock-log model will allow us to translate measurements through casing into effective porosity and hydrocarbon saturation. The wells that are shown to have the best oil production potential will be recompleted. The recompletions will be optimized by evaluating short radius lateral recompletions as well as other recompletion techniques such as the sand consolidation through steam injection.
Date: January 26, 1998
Creator: Phillips, Chris; Moos, Dan; Clarke, Don; Nguyen, John; Tagbor, Kwasi; Koerner, Roy et al.
Partner: UNT Libraries Government Documents Department

Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource

Description: Fluids have been sampled from 9 wells and 2 fumaroles fromthe East Flank of the Coso hydrothermal system with a view toidentifying, if possible, the location and characteristics of the heatsource inflows into this portion of the geothermal field. Preliminaryresults show that there has been extensive vapor loss in the system, mostprobably in response to production. Wells 38A-9, 51-16 and 83A-16 showthe highest CO2-CO-CH4-H2 chemical equilibration temperatures, rangingbetween 300-340oC, and apart from 38A-9, the values are generally inaccordance with the measured temperatures in the wells. Calculatedtemperatures for the fractionation of 13C between CO2 and CH4 are inexcess of 400oC in fluids from wells 38A-9, 64-16-RD2 and 51A-16,obviously pointing to equilibrium conditions from deeper portions of thereservoir. Given that the predominant reservoir rock lithologies in theCoso system are relatively silicic (granitic to dioritic), the isotopicsignatures appear to reflect convective circulation and equilibrationwithin rocks close to the plastic-brittle transition. 3He/4He signatures,in conjunction with relative volatile abundances in the Coso fluids,point to a possibly altered mantle source for the heat sourcefluids.
Date: January 8, 2007
Creator: Christenson, B.W.; Kennedy, B.M.; Adams, M.C.; Bjornstad, S.C. & Buck, C.
Partner: UNT Libraries Government Documents Department

Water injection as a means for reducing non-condensible andcorrosive gases in steam produced from vapor-dominated reservoirs

Description: Large-scale water injection at The Geysers, California, hasgenerated substantial benefits in terms of sustaining reservoir pressuresand production rates, as well as improving steam composition by reducingthe content of non-condensible gases (NCGs). Two effects have beenrecognized and discussed in the literature as contributing to improvedsteam composition, (1) boiling of injectate provides a source of "clean"steam to production wells, and (2) pressurization effects induced byboiling of injected water reduce upflow of native steam with large NCGconcentrations from depth. In this paper we focus on a possibleadditional effect that could reduce NCGs in produced steam by dissolutionin a condensed aqueous phase.Boiling of injectate causes pressurizationeffects that will fairly rapidly migrate outward, away from the injectionpoint. Pressure increases will cause an increase in the saturation ofcondensed phase due to vapor adsorption on mineral surfaces, andcapillary condensation in small pores. NCGs will dissolve in theadditional condensed phase which, depending upon their solubility, mayreduce NCG concentrations in residual steam.We have analyzed thepartitioning of HCl between vapor and aqueous phases, and have performednumerical simulations of injection into superheated vapor zones. Oursimulations provide evidence that dissolution in the condensed phase canindeed reduce NCG concentrations in produced steam.
Date: January 8, 2007
Creator: Pruess, Karsten; Spycher, Nicolas & Kneafsey, Timothy J.
Partner: UNT Libraries Government Documents Department

Fracture Detection: Interpretation of Well Logs to Select Packer Seats and Locate Injection Intervals

Description: A wireline and mud logging program has been conducted in conjunction with redrilling operations in well EE-3 at the Fenton Hill Hot Dry Rock (HDR) site near Valles Caldera, New Mexico. The trajectory for the new bore, EE-3A, penetrated a fractured zone stimulated from adjacent well EE-2 and thereby established hydraulic communication. To test and stimulate selected zones in EE-3A inflatable open hole packers designed for high temperature service were used. Proper identification and selection of packer seats was crucial to the success of the project. The logging program successfully identified five competent packer seats in six attempts. Wireline temperature, caliper, sonic televiewer and natural gamma ray logs were used in conjunction with mud logs, drill cuttings and drilling parameter data to locate fractures, out-of-gage hole, temperature anomalies and mineralized zones which were avoided in selection of the packer seats.
Date: January 21, 1986
Creator: Dreesen, D. S.; Burns, K. L.; Chavez, P.; Dash, Z. V.; Kelkar, S.; Kolar, J. et al.
Partner: UNT Libraries Government Documents Department

Tracer Recovery and Mixing from Two Geothermal Injection-Backflow Studies

Description: Injection-backflow tracer testing on a single well is not a commonly used procedure for geothermal reservoir evaluation, and, consequently, there is little published information on the character or interpretation of tracer recovery curves. Two field experiments were conducted to develop chemical tracer procedures for use with injection-backflow testing, one on the fracture-permeability Raft River reservoir and the other on the matrix-permeability East Mesa reservoir. Results from tests conducted with incremental increases in the injection volume at both East Mesa and Raft River suggests that, for both reservoirs, permeability remained uniform with increasing distance from the well bore. Increased mixing during quiescent periods, between injection and backflow, at Raft River suggest an area near the well bore that has a hydrologic character different from the far well bore environment. Increased flow rates for East Mesa testing resulted in a general decrease in mixing. Comparison of recovery curves from the Raft River reservoir with those from the East Mesa reservoir suggests that mixing is greatest, and therefore permeability is greatest, in the fractured reservoir. These test results indicate that injection-backflow testing with tracers can be used successfully to characterize flow in the near-well bore environment.
Date: December 15, 1983
Creator: Capuano, R.M.; Adams, M.C. & Wright, P.M.
Partner: UNT Libraries Government Documents Department

Mapping the Acid Stimulation in the Beowawe Geothermal Field Using Surface Electrical Potentials

Description: A surface electrical potential system was fielded during the chemical stimulation of the Rossi 21-19 well in the Beowawe Geothermal Field. The technique, which measures variations in resistivity resulting from the flow of conductive fluid into the reservoir, was not only shown to be highly sensitive, not only to the chemical treatment, but also to the in situ conductive zones before any acid injection. A review of the experiment and a preliminary interpretation of the data are presented. The data provide convincing evidence that it should be possible to map the treated zone as well as the primary pretreatment in situ conductive zones.
Date: December 15, 1983
Creator: Hart, Carolyne M.; Engi, Dennis & Morris, Harris E.
Partner: UNT Libraries Government Documents Department

Disposal of Flashed Brine Dosed with CaCO{sub3} Scale Inhibitor: What Happens When the Inhibitor is Exhausted?

Description: A freshly flashed geothermal liquid, previously dosed with inhibitor and super-saturated with calcite was injected into another well where it displaced an unflashed counterpart of itself around the wellbore. Back-production of the injectate, and subsequently the native fluid, has yielded data for the rate that a scale inhibitor is degraded after injection. The circumstance also displays a novel mechanism whereby two fluids that do not physically mix never the less reactive with one another through the reservoir rock's serving a role of intermediary. The results have been further interpretated to conclude that in some circumstances a short lifetime for the scale inhibitor is not necessarily a problem for long-term injection.
Date: December 15, 1983
Creator: Michels, D.E.
Partner: UNT Libraries Government Documents Department

Injection recovery based on production data in unit 13 and unit 16 areas of The Geysers field

Description: Steam production data from 13 wells including and surrounding Unit 13 injection well I-3 and 15 production wells including and surrounding Unit 16 injection well I-5 are analyzed to estimate steam decline rates with and without water injection. Such information is then utilized to estimate the first year recovery factor due to water injection in the southwest area of Unit 13 and the Unit 16 wellfields.
Date: January 1, 1992
Creator: Goyal, K.P. & Box, W.T., Jr.
Partner: UNT Libraries Government Documents Department

Fracture-Flow-Enhanced Solute Diffusion into Fractured Rock

Description: We propose a new conceptual model of fracture-flow-enhanced matrix diffusion, which correlates with fracture-flow velocity, i.e., matrix diffusion enhancement induced by rapid fluid flow within fractures. According to the boundary-layer or film theory, fracture flow enhanced matrix diffusion may dominate mass-transfer processes at fracture-matrix interfaces, because rapid flow along fractures results in large velocity and concentration gradients at and near fracture-matrix interfaces, enhancing matrix diffusion at matrix surfaces. In this paper, we present a new formulation of the conceptual model for enhanced fracture-matrix diffusion, and its implementation is discussed using existing analytical solutions and numerical models. In addition, we use the enhanced matrix diffusion concept to analyze laboratory experimental results from nonreactive and reactive tracer breakthrough tests, in an effort to validate the new conceptual model.
Date: December 15, 2007
Creator: Wu, Yu-Shu; Ye, Ming & Sudicky, E.A.
Partner: UNT Libraries Government Documents Department

Fracture opening/propagation behavior and their significance on pressure-time records during hydraulic fracturing

Description: Hydraulic fracturing with constant fluid injection rate was numerically modeled for a pair of rectangular longitudinal fractures intersecting a wellbore in an impermeable rock mass, and numerical calculations have been performed to investigate the relations among the form of pressure-time curves, fracture opening/propagation behavior and permeability of the mechanically closed fractures. The results have shown that both permeability of the fractures and fluid injection rate significantly influence the form of the pressure-time relations on the early stage of fracture opening. Furthermore it has been shown that wellbore pressure during fracture propagation is affected by the pre-existing fracture length.
Date: January 1, 1992
Creator: Kojima, Takashi; Nakagawa, Yasuhiko; Matsuki, Koji & Hashida, Toshiyuki
Partner: UNT Libraries Government Documents Department

An investigation of radial tracer flow in naturally fractured reservoirs

Description: This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile region where longitudinal dispersion and convection take place and a stagnant region where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared to those previously presented in literature by Moench and Ogata, Tang et al., Chen et al., and Hsieh et al. The solution is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., for short times) was carried out. The influence of various dimensionless parameters that enter into the solution was investigated. A discussion of results obtained through the Crump and Stehfest algorithm is presented, concluding that the Crump method provides more reliable tracer concentrations.
Date: January 1, 1991
Creator: Jetzabeth, Ramirez-Sabag; Fernando, Samaniego V.; Jesus, Rivera R. & Rodriguez, Fernando
Partner: UNT Libraries Government Documents Department

1982 THERMAL SHALLOW RESERVOIR TESTING

Description: An extensive study of the Thermal Shallow Reservoir at The Geysers was performed in 1982 to improve our understanding of the source and flow patterns of steam in the shallow anomaly and how they relate to the Thermal 4 blowout. This project included gathering and analyzing pressure transient, enthalpy, tracer and chemical data and developing a reservoir model that was consistent with this data. Following the pressure transient testing and analysis, a convection-plume with lateral-flow model was proposed. Subsequent analysis of enthalpy, tracer and chemical data corroborated this model. The high flowrate wells--Thermal 4, Thermal 10, Thermal 11 and Magma 1--produce from the high-pressure, high-permeability upflow zone. The source of this upflow is a limited fracture system connecting the shallow anomaly with the underlying main reservoir. The outlying low-pressure, low-permeability wells are supplied by lateral flow of steam from the central area. The pressure gradient from the core to the periphery is caused by condensation in the flanks.
Date: January 22, 1985
Creator: Mogen, P.; Pittinger, L. & Magers, M.
Partner: UNT Libraries Government Documents Department

Evaluation of Porous Medium Permeability by Acoustic Logging Finds Geothermal Applications

Description: In a well, after an acoustic waveform has circulated through the surrounding porous media, the study of its alteration can help in evaluating their permeability. The treatment of the acoustic compressional wave's first three cycles yields a unique parameter called I-c. The recording of this I-c log all along any open hole interval is now possible by respecting some practical rules known by logging companies. Large flows of fluid found in geothermal low-enthalpy operations have provided an opportunity to check the validity of this method. Cumulative I-c derived permeability with depth (''EXAFLO'' log) correlates with the flowmeter log, as examples will show. Some new aspects of the theory underlying the I-c/permeability relationship have been developed and are described here.
Date: January 21, 1986
Creator: Conche, B.; Lebreton, F. & Rojas, J.
Partner: UNT Libraries Government Documents Department

FRACSL CODE DEVELOPMENT AND CORRELATION OF EAST MESA TEST RESULTS

Description: The FRACSL flow and transport code is under development as part of an effort to improve reservoir characterization techniques. The present version simulates a two-dimensional, isothermal reservoir composed of a global fracture network imbedded in a porous media. FRACSL simulates the hydraulic response of a reservoir to injection or backflow. The code simulates the movement of injected tracers within the reservoir by adding advective and random dispersive motions of discrete particles. FRACSL has been benchmarked against theoretical flow and transport responses in simple systems. It has been used to simulate a benchscale physical model and to correlate flow and dispersion data from the East Mesa Hydrothermal Injection Test Program. Correlation of East Mesa data has provided an estimate of an anisotropic hydraulic conductivity, a natural drift in the reservoir, and dispersivity.
Date: January 22, 1985
Creator: Clemo, T.M.
Partner: UNT Libraries Government Documents Department

Boiling and condensation processes in the Cerro Prieto beta reservoir under exploitation

Description: The deep Cerro Prieto (Baja California, Mexico) beta reservoir is offset vertically by the southwest-northeast trending, normal H fault. Under exploitation pressures in the upthrown block have decreased strongly resulting in boiling and high-enthalpy production fluids. Significant differences in fluid chemical and isotopic compositions are observed in the two parts of the reservoir and particularly in an anomalous zone associated with the H fault. These differences result from intense boiling and adiabatic steam condensation, as well as from leakage of overlying cooler water along the fault.
Date: January 1, 1992
Creator: Truesdell, Alfred; Manon, Alfredo; Quijano, Luis; Coplen, Tyler & Lippmann, Marcelo
Partner: UNT Libraries Government Documents Department

An accurate formulation of the solubility of Co{sub 2} in water, for geothermal applications

Description: The solubility correlations for the H{sub 2}O-CO{sub 2} system applied so far for numerical simulation of geothermal reservoir and well flows are crude. This is due, at least partly, to the significant disagreement existing between the solubility models and results published in the specialized literature. In this work we analyze the reasons underlying this disagreement. On this basis, we propose a thermodynamically correct, and numerically accurate model for the solubility of carbon dioxide in water. Its range of validity is up to 350 C and 500 bar. Our main contributions are: (a) the adoption of an equation of state for the gas phase that realistically accounts for the non-ideal behavior of both components and that of the mixture, within the P-T range considered; and (b) to accurately include the effects of temperature and pressure on the solubility of carbon dioxide in the liquid phase. The proposed model fits the available phase equilibrium data for the H{sub 2}O-CO{sub 2} system nicely. In particular, it does not present the severe conflict between the linearity of the model and the lack of linearity of the data, evident in earlier models. The tight fit obtained with our model indicates that the complexities of H{sub 2}-CO{sub 2} phase equilibrium are well represented by it.
Date: January 1, 1992
Creator: Iglesias, Eduardo R. & Moya, Sara L.
Partner: UNT Libraries Government Documents Department