High Temperature Geothermal Elastomer Compund Development

Reliable casting packer seal elastomers for the unusually severe geothermal environment at 260 C (500 F) did not exist in 1976. L'Garde, Inc., was awarded a contract to fulfill this need by the US Department of Energy. Successful development was completed in 1979. Compounds based on four different polymer systems were developed, all of which exceed the contract requirements. Successful laboratory tests above 300 C (575 F) have been performed with packer seals. Field tests to temperatures as high as 317 C (603 F) have been performed on static O-rings in a cablehead. Successful, dynamic, drill bit seal tests were run with a presoak temperature of 288 C (550 F). The successful compounds are based on the following polymer systems: EPDM; FKM; EPDM/FKM blend, and propylene-TFE

High-temperature Y267 EPDM elastomer field and laboratory experiences, September 1982

High performance elastomers were developed for hostile geothermal environments which clearly advance the state-of-the-art. The Y267 EPDM compound is eminently successful and has accumulated broad laboratory and field test experience. Over 15 separate tests are reviewed with about 95% performed independently by other organizations. The tests include a broad spectrum of environments with temperatures in excess of 320 C (608 F), differential pressures up to 138 MPa (20,000 psi) and in fluids including brine, oils, isobutane, and others

Geothermal elastomeric materials. Twelve-months progress report, October 1, 1976--September 30, 1977

Progress is reported on efforts to develop elastomers for packer seal element applications which will survive downhole geothermal well chemistry at 260/sup 0/C (500/sup 0/F) for 24 hours. To achieve this development, a three level elastomer testing and evaluation program was established. The first level Screening Tests is a broad screening of potential candidates and with the end objective to filter out the more promising candidates for more expensive subsequent testing. The battery of tests include standard ASTM tests and a special test developed to test extrusion resistance using specimens all made from sheet stock. The second level or Simulation Tests provide a laboratory equivalent of downhole conditions using synthetic geothermal fluid. Full scale packer seals are tested under simulated operational conditions by a test fixture. The third level or In-Situ Tests which are currently in the planning, provide for testing the most favored materials in-situ in the geothermal well. A test module provides for testing of the specimen without interfacing with the well casing. A test module freely hanging on a wireline has much lower probability of causing a problem, such as becoming lodged in the well, as compared to an operational casing packer. This maximizes the number of wells (hence geothermal environments) where access can be gained and In-Situ Testing performed. During this period commercially available polymers were investigated. Most of the work centered around formulating peroxide cured Vitons and some on EPDMs, butyls, and resin cured Vitons. Of the formulations tested to date the EPDMs appear most promising and the peroxide cured Vitons next most promising. However, data is too sparse to make any firm conclusions at this time. Minor tasks were performed evaluating current commercially available elastomers used in oil tools and conceptualization of casing packer for the geothermal application

Expression of Anthocyanins in Callus Cultures of Cranberry (\u3ci\u3eVaccinium macrocarpon Ait\u3c/i\u3e)

Expression of anthocyanins and other flavonoids in callus cultures established from different parts of cranberry plant was investigated and the effect of explant source on the in vitro product was determined. Callus cultures were initiated from different parts of the plant in a modified Gamborg\u27s medium with 5.37 μM α-naphthaleneacetic acid, 0.45 μM 2,4-dichlorophenoxyacetic acid, and 2.32 μM kinetin in the dark at 25°C. Callus cultures accumulated anthocyanins only on exposure to light and maximum concentration was observed by day 12. The cultures had lower levels of anthocyanins and only cyanidin 3-galactoside, cyanidin 3-glucoside, and cyanidin 3-arabinoside were identified in all cultures regardless of source of explant. Proanthocyanidin accumulation in cultures was independent of light, and levels were higher than in mature fruit. Exposure to light induced accumulation of flavonols and enhanced activity of phenylalanine ammonia-lyase in the cultures

Rural and Urban Differences in Welfare Exits: Minnesota Evidence 1986-1996

This article examines differences between rural and urban counties in the duration of welfare spells. We report evidence that suggests that parents from farming-dependent counties and rural counties are more likely to have shorter spells on welfare. The evidence appears consistent with the literature on rural low-income families in that there may be a concentration of low-wage jobs in rural counties. The difference between rural and urban areas is relevant to welfare policy as it pertains to caseload numbers, parents more likely to reach the sixty-month time limit, and parents more likely to trigger time-based policies, such as employment search. The study uses administrative data of Aid to Families With Dependent Children recipients from the state of Minnesota between 1986 and 1996. The methodology includes constructing descriptive statistics, calculating Kaplan-Meier estimates, and performing a Cox regression analysis with robustness checks across all three methods. Copyright 2005 Blackwell Publishing Ltd..