Numerical Investigations into the formation of a high temperature reservoir

Conference · Thu Jan 28 04:00:00 EST 1993

OSTI ID:888901

Shook, Mike

This paper summarizes an ongoing numerical modeling effort aimed at describing some of the thermodynamic conditions observed in vapor-dominated reservoirs, including the formation of a high temperature reservoir (HTR) beneath the "typical" reservoir. The modeled system begins as a hot water geothermal reservoir, and evolves through time into a vapor-dominated reservoir with a HTR at depth. This approach taken here to develop a vapor-dominated system is similar to that of Pruess (1985), and involves induced boiling through venting. The reservoir description is intentionally generic, but serves to describe a means of evolution of conditions observed (in particular) at The Geysers. This study addresses the question of HTR formation numerically. The reservoir model and approach used is similar to that of Pruess (1985); however, vapor pressure lowering effects were included for the rock matrix. Results of this study indicate that a high temperature reservoir may occur as a steady state component of a "typical" vapor-dominated reservoir. Fractures within the HTR are dry; however, saturated conditions exists in the rock matrix. Pressures at depth follow a vapor pressure with depth relationship. Temperatures at depth are large (relative to saturated conditions) because of superheat in the fractures and vapor pressure lowering in the matrix. Drying out the fracture network at depth appears to be what drives the system to form a high temperature reservoir; however, adsorption in the rock matrix allows for saturated conditions to prevail.

• Research Organization: Idaho National Engineering Laboratory (INEEL), Idaho Falls, ID
• Sponsoring Organization: USDOE
• OSTI ID: 888901
• Report Number(s): SGP-TR-145-13
• Country of Publication: United States
• Language: English

Related Subjects

Geothermal Legacy