MUTNOVSKY SCIENTIFIC DRILLING PROGRAM TARGETS

Alexey V. Kiryukhin Institute of Volcanology and Seismology FEB RAS

Outline:

Introduction to the Mutnovsky geothermal field

Conceptual hydrogeological model and numerical modeling of the Mutnovsky geothermal field

Conceptual model of the Mutnovsky volcanomagma system

Targets and feasibility of the Mutnovsky Scientific Drilling Program (MSDP)

Exploration works began in 1978, including delineation of surface manifestations, temperatures, soil gas surveys, resistivity surveys, T-gradient drilling, and drilling of the exploration wells. Eighty nine exploration wells were drilled by 1991 (G.M. Assaulov et al, 1987, V.M. Sugrobov et al, 1986).

Mutnovsky Geothermal Field Introduction

The Dachny fumarole field was discovered in 1960 by I.T. Kirsanov, and described in details by E.A. Vakin (1976).

A Mutnovsky 50 MWe power plant feasibility study performed by WestJec (1996-1997) was based on TOUGH2-modeling of different exploitation scenarios (A.V. Kiryukhin, 1996) confirmed 50 MWe potential of Mutnovsky geothermal field.

Mutnovsky Geothermal Field Introduction

Flow tests from production wells conducted during 1983-1987 time period, which confirmed the possibility of the 50 MWe production based on a sum of the single well flow rate values.

V-Mutnovsky Site: 12 MWe PP put in operation since 1999

Dachny Site: 50 MWe PP put in operation since 2002

Mutnovsky Geothermal Field Introduction

Mutnovsky area include magmaticsystem of the active Mutnovsky volcano, numerios steam fields and hot springs

Mutnovsky Geothermal Field Introduction

Conceptual hydrogeological model and numerical modeling of the Mutnovsky geothermal field

Conceptual Hydrogeological Model

Mutnovsky is a fracture type geothermal field: Main and North-East single-faulttype zones include Dachny and V-Mutnovsky production reservoirs

Conceptual hydrogeological model of the Dachny site Mutnovsky geothermal field was verified based on

Dachny Site Conceptual Hydrogeological Model

•circulation losses and production zones distribution data,•mapping of active fracture zones, •gas and fluid chemistry data, •secondary minerals distributions,•recent results of drilling,•geothermal analog data

Central part of the Dachny represent a “single fault” type geothermal reservoir.

The plane of the Main production zone intersects the active magma feeding systemof Mutnovsky volcano at elevations of +250 - +1250m at a distanceof 8 km from production site.

Conceptual Hydrogeological Model (Geometry of Production Zone)

“Single fault” nature of the Main Production Zone demonstrated by small deviations of the points of the production () and full circulation loss () from plane equation formula Z = -1.691076246561*Х +0.48880109651512*Y +65583.1 Filled symbols correspond to production wells.

Conceptual Hydrogeological Model (Geometry of Production Zone)

Wells isolated from “Single fault” in Dachny Site show low productivity

Numerical modeling (2003-05) of the Main production zone (Dachny) used to estimate additional drilling schedule need to maintainsustainable steam production for 50 MWe PP.

Numerical Modeling

Model calibrated based on 2002-2004 exploitation data

Numerical Modeling

Numerical modeling confirm necessity of additional exploitation wells drilling (7 wells in 10 years) to maintain sustainable steam production for 50 MWe Power Plant.

Numerical Modeling

Modeling of Exploitation

Geotherm JS requested sub-contractor to drill three deviated 2.5 km deep wells in 2007-2009 to maintain sustainable production ofPP’s

Conceptual model of the Mutnovsky volcanomagma system

Mutnovsky active crater (Mutnovsky IV) has fumaroles as hot as 507oC and emits a continuous SO2-rich plume. Total heat output estimated as 1700 MW (B.G. Polyak, 1988)), discharging fumaroles fluids include steam (92.8 wt%), CO2 (3.3 wt %), SO2 (2.9 wt %),H2S (0.6 wt%), HCl (0.3 wt%), HF (0.1 wt%) and H2 (Y.P. Trukhin, 2003, M. Zelensky, 2003).

Rough estimations of the natural steam upflow rate based on assumed heat output (B.G. Polyak, 1988, Y.P. Trukhin, 2003)) yield to 566 kg/s steam rate with the enthalpy of 3000 kJ/kg. That is equivalent of 480 MWe geothermal Power Plant (if 1.17 kg/s per MWe conversion rate applied to steam at 230-260 bars and 500 oC, O. Fridleifsson, pers. com., 2005).

Based on analysis of the 37 geothermal fields case history sustainable exploitation rate is 5.3 times greater than natural upflow rate (S. Sanyal, 2005), that mean possibility of the 2544 MWe sustainable production from Mutnovsky volcano conduit zone.

Well 035 is closest well to thepoint intermediate between the active vent of magma system and the production geothermal field

Well 035 located 3.16 km from Bottom Fieldof the Mutnovsky volcano crater

Our concept is to directionally drill into the fracture zone at a point intermediate between the active vent of magma system and the production geothermal field, in order to test the relationship between the two systems.

Mutnovsky 50 MWe Power Plant production zone lateral arrangement provides an ideal geometry for exploring magma-hydrothermal connection by drilling :

Conclusions:

Identifying magmatic components in fluids proximal to theconduit and their relationship to fluids of producing system.

Monitoring physical parameters to assess the hydraulic connections of the volcanicand geothermal systems.

In-situ measurement of response of magma-hydrothermal system to frequent earthquakes.

Determining the overall volatile and thermal budget of the volcano by assessing subsurface hydrothermal convection as well as emission to atmosphere.

Identifying technical and economical feasibility of the sustainable steam production from Mutnovsky volcano conduit zone.

Steam contribution to the Mutnovsky PP, in case of significant steam production fromscientific well.