Long-Term Flow Test #1, Roosevelt Hot Springs, Utah

The Roosevelt Hot Springs, Utah geothermal field has been the site of numerous investigations into the behavior of a geothermal system. However, a detailed description of the reservoir is lacking. This paper presents the results of the 237 day Long-Term Flow Test #1, conducted in 1977 and 1978, followed by a 100 day pressure buildup. The responses from one production well and three pressure observation wells, ranging 600 to 12,000 feet from the production well, were used. This study illustrates the utility of a reevaluation of a geothermal system using old, pre-exploitation data and is part of an ongoing case study of the Roosevelt Hot Springs system. Specific objectives are an improved interpretation of the geothermal reservoir, an estimate of aquifer behavior, and the primary reservoir volume

Decline curve analysis of vapor-dominated reservoirs

Geothermal Program activities at the INEEL include a review of the transient and pseudosteady state behavior of production wells in vapor-dominated systems with a focus on The Geysers field. The complicated history of development, infill drilling, injection, and declining turbine inlet pressures makes this field an ideal study area to test new techniques. The production response of a well can be divided into two distinct periods: transient flow followed by pseudo-steady state (depletion). The transient period can be analyzed using analytic equations, while the pseudo-steady state period is analyzed using empirical relationships. Yet by reviewing both periods, a great deal of insight can be gained about the well and reservoir. An example is presented where this approach is used to determine the permeability thickness product, kh, injection and production interference, and estimate the empirical Arps decline parameter b. When the production data is reinitialized (as may be required by interference effects), the kh determined from the new transient period is repeatable. This information can be used for well diagnostics, quantification of injection benefits, and the empirical estimation of remaining steam reserves

Permeability-thickness determination from transient production response at the southeast geysers

The Fetkovich production decline curve analysis method was extended for application to vapor-dominated geothermal reservoirs for the purpose of estimating the permeability-thickness product (kh) from the transient production response. The analytic dimensionless terms for pressure, production rate, decline rate, and decline time were derived for saturated steam using the real gas potential and customary geothermal production units of pounds-mass per hour. The derived terms were numerically validating using ``Geysers-line`` reservoir properties at initial water saturation of 0 and at permeabilities of 1, 10, and 100 mD. The production data for 48 wells in the Southeast Geysers were analyzed and the permeability-thickness products determined from the transient production response using the Fetkovich production decline type curve. The kh results were in very good agreement with the published range at the Southeast Geysers and show regions of high permeability-thickness

Analysis of reinjection strategies for The Geysers

The Geysers has undergone severe pressure decline in recent years, and reinjection of condensate is thought to be one key to sustaining current steam production. Other methods of pressure maintenance include load cycling, or reduction of steam production during off-peak hours. It is likely that a combination of these two will prove to be optimum in providing pressure and fluid maintenance. This paper presents preliminary results of a study of various injection schemes for The Geysers. A number of injection scenarios are investigated, and an optimum scheme (based on specific parameters) is identified for two different quantities of reinjection. 9 refs., 14 figs., 1 tab

Withdrawal rates as a consequence of disclosure of risk associated with manipulation of the cervical spine

<p>Abstract</p> <p>Background</p> <p>The risk associated with cervical manipulation is controversial. Research in this area is widely variable but as yet the risk is not easily quantifiable. This presents a problem when informing the patient of risks when seeking consent and information may be withheld due to the fear of patient withdrawal from care. As yet, there is a lack of research into the frequency of risk disclosure and consequent withdrawal from manipulative treatment as a result. This study seeks to investigate the reality of this and to obtain insight into the attitudes of chiropractors towards informed consent and disclosure.</p> <p>Methods</p> <p>Questionnaires were posted to 200 UK chiropractors randomly selected from the register of the General Chiropractic Council.</p> <p>Results</p> <p>A response rate of 46% (n = 92) was achieved. Thirty-three per cent (n = 30) respondents were female and the mean number of years in practice was 10. Eighty-eight per cent considered explanation of the risks associated with any recommended treatment important when obtaining informed consent. However, only 45% indicated they always discuss this with patients in need of cervical manipulation. When asked whether they believed discussing the possibility of a serious adverse reaction to cervical manipulation could increase patient anxiety to the extent there was a strong possibility the patient would refuse treatment, 46% said they believed this could happen. Nonetheless, 80% said they believed they had a moral/ethical obligation to disclose risk associated with cervical manipulation despite these concerns. The estimated number of withdrawals throughout respondents' time in practice was estimated at 1 patient withdrawal for every 2 years in practice.</p> <p>Conclusion</p> <p>The withdrawal rate from cervical manipulation as a direct consequence of the disclosure of associated serious risks appears unfounded. However, notwithstanding legal obligations, reluctance to disclose risk due to fear of increasing patient anxiety still remains, despite acknowledgement of moral and ethical responsibility.</p

Small molecule binding sites on the Ras:SOS complex can be exploited for inhibition of Ras activation.

Constitutively active mutant KRas displays a reduced rate of GTP hydrolysis via both intrinsic and GTPase-activating protein-catalyzed mechanisms, resulting in the perpetual activation of Ras pathways. We describe a fragment screening campaign using X-ray crystallography that led to the discovery of three fragment binding sites on the Ras:SOS complex. The identification of tool compounds binding at each of these sites allowed exploration of two new approaches to Ras pathway inhibition by stabilizing or covalently modifying the Ras:SOS complex to prevent the reloading of Ras with GTP. Initially, we identified ligands that bound reversibly to the Ras:SOS complex in two distinct sites, but these compounds were not sufficiently potent inhibitors to validate our stabilization hypothesis. We conclude by demonstrating that covalent modification of Cys118 on Ras leads to a novel mechanism of inhibition of the SOS-mediated interaction between Ras and Raf and is effective at inhibiting the exchange of labeled GDP in both mutant (G12C and G12V) and wild type Ras

Parametric analysis of factors affecting injection and production in geothermal reservoirs

A program was designed to allow the study of the effects of several parameters on the injection of water into and production of fluid from a fractured low porosity geothermal reservoir with properties similar to those at The Geysers. Fractures were modeled explicitly with low porosity, high permeability blocks rather than with a dual-porosity formulation to gain insight into the effects of single fractures. A portion of a geothermal reservoir with physical characteristics similar to those at the Geysers geothermal field was constructed by simulating a single fracture bounded by porous matrix. A series of simulation runs were made.using this system as a basis. Reservoir superheat prior to injection, injection temperature, angle of fracture inclination, fracture/matrix permeability contrast, fracture and matrix relative permeability, and the capillary pressure curves in both fracture and matrix were varied and the effects on production were compared. Analysis of the effects of these parameter variations led to qualitative conclusions about injection and production characteristics at the Geysers. The degree of superheat prior to water injection was found to significantly affect the production from geothermal reservoirs. A high degree of superheat prior to injection increases the enthalpy of the produced fluid and causes the cumulative produced energy to nearly equal that from a reservoir which began injection much earlier. Injection temperature was found to have very little effect on production characteristics. Angle of fracture inclination affects the enthalpy of the produced fluid. Fractures dipping toward the production well allow greater flow of water toward the producer resulting in lower enthalpies of produced fluid. The fracture/matrix permeability contrast was shown to influence the production in an expected way: The lower the contrast, the lower the production rate, and the lower the enthalpy of the produced fluid at a given time. Results obtained by varying relative permeability show that the relative permeability curves used have little effect on the production from the reservoir. This indicates that the transfer between the matrix and the fracture is dominated by capillary forces, thus reducing the importance of the shape of the relative permeability curve. Capillary pressure curves were shown to have a strong effect on production characteristics, further emphasizing the importance of capillary forces in Geysers-type geothermal reservoirs

Reservoir technology research at the INEL

Reservoir engineering research at INEL was aimed at developing a better understanding of The Geysers and developing better tools with which to study flow in fractured geothermal reservoirs in general. Two specific topics were studies in the last year: matrix fracture interactions and decline curve analysis. A third project, revisiting the behavior of the `high-temperature reservoir` (HTR), was started near the end of 1995. These projects are being conducted in collaboration with other researchers and/or private industry. For example, our HTR studies are motivated in part because of new isotopic analyses conducted elsewhere (Walters et al., in preparation). The ultimate goal of these projects is to improve predictive capabilities and reservoir management practices and to extend the commercial life of The Geysers. In addition to conducting engineering research for the Reservoir Technology Program, INEL also continued to assist the Geothermal Technology Organization (GTO) with the development and execution of cooperative research projects. In support of the overall mission of the Reservoir Technology program, INEL also entered into a broad program of subcontracts with industrial groups and universities. These programs support the Reservoir Technology mission by providing support for research topics considered particularly important by the geothermal industry. The GTO projects are summarized below