Geothermal exploration has been highly successful to date in locating targets for drilling. However, the requirements for an economically successful geothermal well are both high flow rate and high temperature. Most geophysical and geochemical exploration methods have not been highly accurate in predicting the depth and actual temperature of a reservoir, nor have they been able to locate high permeability zones. The result is that most geothermal exploration is conducted by drilling core holes to better understand the heat flow in an area followed by drilling of production diameter exploration wells which can be flow tested to ascertain the permeability. The goal of any exploration program is to determine reservoir economics. The cost of wells makes up between one quarter and one half the total cost of producing geothermal power. The number, design, depth of wells and placement of injectors are important to the optimal exploitation of the reservoir. Although early efforts at development have focused on rapid plant construction to begin cash flow, the history of producing fields emphasizes that understanding reservoirs can reduce the risk of rapid temperature or pressure declines and increase the success of step out drilling following initial exploitation. The high cost of large diameter production wells makes the collecting of exploration data on the reservoir through some less expensive method desirable. Geothermal developers are still drilling resources with surface expression, hot springs and surface mappable fractures and faults. As these obvious resources are developed and as the obvious targets in productive fields are exhausted, new exploration tools are needed. One possibility is the use of deep core holes drilled for temperature gradient data to provide more reservoir information. Two methods not previously applied to geothermal reservoir assessment are suggested to augment other data obtained from coreholes.
Date: January 1, 1992
Creator: Petty, Susan; Adair, Richard G. & Livesay, Bill
This paper is a summary of the proposed drilling plan for the first phase (to 2500 feet depth) of the Magma Energy Exploratory Well. The drilling program comprises four phases, spaced approximately one year apart, which culminate in a large-diameter well to a total depth near 20,000 feet. Included here are descriptions of the well design, predictions of potential drilling problems, a list of restrictions imposed by regulatory agencies, an outline of Sandia's management structure, and an explanation of how the magma energy technology will benefit from this drilling.
Date: March 21, 1989
Creator: Finger, John T.; Livesay, Bill J. & Ash, Don