Short-term Flow Tests on Exploratory Well for Geothermal Power Generation in the Oyasu region

November 7, 2017 Project

Mitsui Oil Exploration Co., Ltd. (MOECO) announced today that it conducted short-term flow tests to gauge the capacity of an exploratory well it has drilled in the Oyasu region of Akita Prefecture, Japan in partnership with Idemitsu Kosan Co., Ltd. and INPEX CORPORATION with which it has jointly pursued commercialization studies on geothermal power generation since 2011.

1. Details and objectives

The short-term flow tests (*1) were conducted on Well OYE-6, which was drilled in FY2016 and is one of the exploratory wells (*2) drilled since FY2012. Through these experiments, the companies verified details concerning well production capacity (volume of steam), underground temperatures, chemical composition of geothermal fluids, water permeability in the vicinity of the well, and other matters.

(*1) Short-term experiments to locate the presence of steam within exploratory wells

(*2) Wells drilled to study underground structures and geothermal reservoir conditions in the initial stage of the study

2. Overview of studies to date

(1) Stage 1: Completed in FY2011

Superficial surveys (ground-level geological surveys, gravitational exploration, electromagnetic exploration, etc.)

(2) Stage 2: FY2012-2017 (planned)

(i) Drilling survey, building roads for equipment transportation, etc.

Drilling exploratory wells OYE-1~7 to study geological structures, underground temperatures and water permeability

(ii) Hot spring monitoring survey

Monitoring hot spring temperatures, yields, and chemical composition at nearby hot spring wells

3. Future schedule

MOECO and its partners will determine whether to transition to the third stage of studies (including drilling exploratory wells, production and injection experiments, assessment of reservoir capacity and environmental surveys) within FY2017 based on the results of the short-term flow tests and future studies.

Short-term Flow Tests of Exploratory well