The first multi-stage completion in a deep, hot, and low permeability volcanic rock of the Minami-Nagaoka Field, Niigata Prefecture, Japan, was successfully completed using six propped fracture treatment stages in 2001. This concept was introduced through the joint research program, “Productivity Improvement in a Deep Volcanic Rock Reservoir”, between Japan National Oil Corporation and Teikoku Oil Co., Ltd. started in 1997. The history and current status of Minami-Nagaoka Field is briefly reviewed and the outline of this project including the background of project initiation is discussed.
A brand new international scientific ocean drilling will start from October 1st, 2003, instead of the ODP (Ocean Drilling Program). The new program calls “IODP: Integrated Ocean Drilling Program” that integrates multi-platforms for scientific ocean drilling. The IODP has scientific initiatives for the future scientific activities that will be archived through the platforms. Japan has a responsibility to provide a riser drilling capability for the IODP, and constructing a state of the art drilling ship. Her name is “CHIKYU” (means the earth in Japanese). The CDEX (Center for Deep Earth Exploration) was established in the JAMSTEC and play as an implementation organization for the “CHIKYU” under the IODP umbrella. The vessel will be a core capability in the IODP and bring new scientific breakthroughs.
A share of natural gas in the primary energy supply in Japan is about 13% in FY 2000. The figure is lower than the average of OECD by 10 points. The stable supply of gas and expansion of gas uses are essential to Japan. The government issued methane hydrate exploration program in July 2001 as one of measures to secure domestic gas resources. The brief outlines of the program are presented with previous efforts on methane hydrate study in Japan.
The first production test of natural methane hydrate formation was carried out at Mackenzie Delta in the Arctic Canada. Three wells were drilled through the hydrate formation beneath permafrost on a line at 40m distance, where coring, logging, various science experiments and production testing were performed over an 79 day period, from December 25, 2001 to March 14, 2002. This research project was organized and funded by participants from five (5) countries of Japan, Canada, US, Germany and India. Japan National Oil Corporation (JNOC) and Japan Petroleum Exploration Co., Ltd. (JAPER) undertook its operation while the Geological Survey of Canada (GSC) coordinated the science program. The production test was executed at the center well in two methods. One was depressurizing test using Modular Dynamic Formation Tester (MDT), and the other was heating test by circulating hot fluid against a hydrate layer. Post-test wireline log data was obtained and compared with pre-test log data. Down hole temperatures were continuously monitored using fiber optic cables. During the test, cross well tomography survey was run in two adjacent wells at both sides. This paper describes the field operation of the project. All data will be open in August 2004 after a full study and analysis by the project participants.
The Sakhalin 1 Project is one of the oil and gas development projects located on the northeast shelf of Sakhalin Island, water depth is 10 to 60 meters and the thick ice covers the area 6 to 7 months a year. The project was declared commercial by the Sakhalin 1 consortium in October, 2001, and started development period from 2002. Total recoverable reserves are estimated at 307 million tons of oil and 485 billion cubic meters of natural gas. This project consists of three fields, Chayvo, Odoptu and Arkutun-Dagi, which are currently planned to develop in phases 1 to 4, using both offshore and onshore wells. Many of these wells will be drilled using a new drilling technique called ERD (extended reach drilling), which allows oil and gas targets to be drilled by the rig located a great distance away. The first phase of development is focusing on the oil production of Chayvo and Odoptu fields, and the start of the oil production from Chayvo field is scheduled at the end of 2005. The oil will be transported through the pipeline to the marine tanker terminal at DeKastri. Large marine tankers will be escorted by icebreakers using a new developed ice passport concept, which would confirm the safety and reliability of plans for the year-round export operations. These advanced technologies will be applied significantly to reduce the overall cost of development and to minimize environmental impact.
K-Ar dating was carried out on groundmass fractions of five volcanic rock samples collected from the Odose Formation in the western Tsugaru district, Aomori Prefecture. Lava flows at different stratigraphic positions were sampled. Early to Middle Miocene ages ranging from about 20 Ma to 14 Ma were determined by the isotope dilution method. Three age determinations (19.7±0.5 Ma, 19.1±0.5 Ma, 18.2±0.5 Ma) are reliable as they are concordant with stratigraphy, whereas another two (14.4±0.4 Ma, 16.9±0.5 Ma) are thought to have been affected by age lowering. On the basis of our results and existing radiometric ages, the Odose Formation is assigned to the upper Lower Miocene. The volcanic activity of this formation began about 20 Ma and ceased about 18 Ma ; probably it was coeval with the paleomagnetically suggested counterclockwise rotation of Northeast Japan associated with the opening of the Japan Sea.
Bintuni Basin is a fore-deep basin located in Irian Jaya, Indonesia. A third party has certified a 14.4 TCF of proven gas for the Wiriagar, Berau and Muturi PSCs in Irian Jaya. This paper describes gas-bearing reservoirs including Jurassic and Paleocene. The Palaeocene sandstones had not been recognized as a reservoir before the Wiriagar Deep #1 was drilled. In addition to the description of these reservoirs, the reasons why giant gas fields remained undiscovered to date are discussed. Top Jurassic horizon was picked up and mapped based on an assumption of a constant thickness between base of Cretaceous and top of Palaeocene. In the swampy onshore Wiriagar PSC, a so-called "deep reflector" was picked as intra-Eocene. There was no tie line throughout the transitional area between onshore Wiriagar and offshore Berau PSCs. Palaeocene was found to be thick beyond operator's prognoses because turbidite lobes are developed in and around the location of Wiriagar Deep #1. As a result, a spill-point between Wiriagar Deep structure and nearby structures was deepened, and P structure was interpreted to be connected with Wiriagar Deep structure. On the other hand, high velocity due to the presence of thick carbonates in the western flank of the Vorwata structure was encountered. The saddle of the depth map between Vorwata and Wiriagar structures was deeper than that of the time map. Depth conversion of "pre-carbonates" is as difficult as that of "pre-salt". Although the Vorwata and Wiriagar fields have proven to be giants, these giant fields have had lain undiscovered due to the above-mentioned underestimations.