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Analysis and interpretation of clustered microseismicity at geothermal and petroleum reservoirs

IP.com Disclosure Number: IPCOM000128054D
Original Publication Date: 1999-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 10 page(s) / 33K

Publishing Venue

Software Patent Institute

Related People

Rieven, Shirley A: AUTHOR [+3]

Related Documents

http://theses.mit.edu:80/Dienst/UI/2.0/Describe/0018.mit.theses/1999-86: URL

Abstract

This thesis presents the analysis and interpretation of four microearthquake clusters near geothermal and petroleum reservoirs. One cluster was induced during a controlled hydraulic fracture experiment conducted by Atlantic Richfield Corporation (ARCO). The other three clusters occurred near geothermal fields in western Italy during condensate reinjection. Analysis of events induced during ARCO's Deep Well Treatment and Injection project demonstrated "; real-time "; hypocenter modeling for hydraulic fracture diagnostics. The injection produced a hydraulic fracture that exhibited strong spatial asymmetry, Analysis of the results suggest that the phenomenon of "; screenout "; may be one mechanism contributing to the observed seismicity's spatial and temporal characteristics and the direction of the asymmetric failure may be related to heterogeneities in formation depositional rtructures. A swarm of events in 1993 near the northern boundary of the Larderello Geothermal field occurred just below an important regional seismic reflector known as the "; K "; horizon. The distribution of events suggests that seismic slip on steeply dipping, northwest-southeast striking Tortonian age normal faults could account for the observations and that high pressure fluids circulating in the fracture zone of the "; K "; horizon cause stress changes and slip on localized patches of the faults. Due to the relative depth of this swarm, compared to 2 reservoir depths, this cluster was attributed to the natural geodynamics of this complex area,

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Analysis and Interpretation of Clustered Microseismicity at Geothermal and Petroleum Reservoirs

by

Shirley A. Rieven
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geophysics

at the Massachusetts Institute of Technology

February, 1999
SIGNATURE OF author: [[signature omitted]]

Department of Earth, Atmospheric, and Planetary Sciences

February 17, 1999

CERTIFIED BY: [[SIGNATURE OMITTED]]

Professor M. Nafi Toksoz

Professor of Geophysics Thesis Advisor ACCEPTED BY: [[SIGNATURE OMITTED]]

Professor Ronald Prinn Department Chair
ARCHIVES MASSACHUSETTS INSTITUTE OF TECHNOLOGY LIBRARIES MAR 31 1999

Massachusetts Institute of Technology Page 1 Dec 31, 1999

Page 2 of 10

Analysis and interpretation of clustered microseismicity at geothermal and petroleum reservoirs

Analysis and Interpretation of Clustered Microseismicity at Geothermal and Petroleum Reservoirs

by

Shirley A. Rieven

Submitted to the Department of Earth, Atmospheric, and Planetary Sciences on February 17, 1999 in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geophysics

ABSTRACT

This thesis presents the analysis and interpretation of four microearthquake clusters near geothermal and petroleum reservoirs. One cluster was induced during a controlled hydraulic fracture experiment conducted by Atlantic Richfield Corporation (ARCO). The other three clusters occurred near geothermal fields in western Italy during condensate reinjection.

Analysis of events induced during ARCO's Deep Well Treatment and Injection project demonstrated " real-time " hypocenter modeling for hydraulic fracture diagnostics. The injection produced a hydraulic fracture that exhibited strong spatial asymmetry, Analysis of the results suggest that the phenomenon of " screenout " may be one mechanism contributing to the observed seismicity's spatial and temporal characteristics and the direction of the asymmetric failure may be related to heterogeneities in formation depositional rtructures.

A swarm of events in 1993 near the northern boundary of the Larderello Geothermal field occurred just below an important regional seismic reflector known as the " K " horizon. The distribution of events suggests that seismic slip on steeply dipping, northwest-southeast striking Tortonian age normal faults could account for the observations and that high pressure fluids circulating in the fracture zone of the " K " horizon cause stress changes and slip on localized patches of the faults. Due to the relative depth of this swarm, compared to

reservoir depths, this cluster was attributed to the natural geodynamics of this complex area,

Analysis of a set of events from the LAGQ seismogenic zone...