Overview of Phase 1
In order to implement Phase 1 of the “Japan’s Methane Hydrate R&D Program” developed in July 2001 by Ministry of Economy, Trade and Industry (METI), the Agency of Natural Resources and Energy consigned the duties to three entities: the Japan Oil, Gas and Metals National Corporation(JOGMEC), National Institute of Advanced Industrial Science and Technology(AIST) and the Engineering Advancement Association of Japan(ENAA), which organized Research Consortium for Methane Hydrate Resources in Japan (or MH21 Research Consortium) under the leadership of Professor Emeritus Shoichi Tanaka, University of Tokyo, acting as the project leader.
The “Japan’s Methane Hydrate R&D Program” describes five areas (exploration, modeling, field production test, development and environment) of technological development required for accomplishing the six goals. The outline of the accomplishments of Phase 1 research is as follows.
Using the Eastern Nankai Trough area as a model sea area, detailed surveys were conducted through MITI seismic surveys and MITI exploratory test well drilling. As a result, it has been found that methane hydrate in the eastern Nankai Trough area is mostly of the same type as that trapped in the sand layer within turbidite sequence and that methane hydrate concentrated zones are distributed. Also, a technique has been established to delineate a methane hydrate concentrated zone based on the seismic data. Thus, the original methane hydrate gas in place within the eastern Nankai Trough area has been evaluated with the probabilistic approach. Furthermore, concerning the 16 methane hydrate concentrated zones in the eastern Nankai Trough area, the original gas in place, reservoir characteristics and seafloor conditions were examined among other things to pick out three locations as candidate areas for offshore production tests.
In the areas off the coast of Japan other than the eastern Nankai Trough, the BSR (Bottom Simulating Reflector) distribution was reviewed based on existing seismic data, referring to the findings obtained from the eastern Nankai Trough.
A mainframe production simulator (MH21-HYDRES) was developed, which can analyze the performance of various production methods including the depressurization, thermal simulation method, and combine methods under the given conditions such as the temperature and pressure of the methane hydrate reservoirs. And by using a fundamental technology developed for testing the physical properties and dissociation behaviours of methane hydrate sediment under the in-situ conditions of the target methane hydrate resources, the reservoir characteristics of the eastern Nankai Trough area were evaluated.
Based on analyses of optimal production methods using the MH21-HYDRES it was cleared that the depressurization method was effective as a main method for production at the eastern Nankai Trough area. The advantage of depressurization method was verified through the second onshore gas production test, for which the test results were very similar to the prediction (predicted gas and water outputs, etc) from the production simulator.
Field Production Test
In order to verify the production method in the field, MH21 conducted the production test twice on methane hydrate trapped in the sand layer beneath the permafrost zone in the Canadian part of the arctic circle.
The First Onshore Gas Hydrate Production test conducted in March 2002 yielded methane gas from a methane hydrate-bearing layer for the first time in the world, using the “hot water circulation method” (the production period: five days, cumulative output: 470 m³). However, some issues were left to be solved later from the viewpoint of the recovery method, including issues of energy efficiency and production continuity. In addition, gas emergence was confirmed by monitoring the process of depressurization by the MDT. It was also found that the methane hydrate-bearing layer has permeability as a result of pressure analysis, etc.
After that, in the Second Onshore Gas Hydrate Production Test conducted in March 2008 (the second year) , MH21 succeeded in continuous production of methane gas “by the depressurization method” for the first time in the world (the production period: six days, cumulative output: 13,000 m³), proving that the depressurization method does work as the production method. For this production test, MH21 installed sand screens to reduce sand production.
Considering the results from the METI Exploratory Test Wells “Tokai-oki to Kumano-nada” and onshore gas hydrate production tests, MH21 examined the concept for the well-drilling plan aimed at offshore production tests. Through such examination, MH21 extracted technical issues to be solved toward the implementation of offshore production tests in Phase 2 (such as cementing and well completion in deep-water shallow formation zones, establishment of a downhole system subject to the implementation of the depressurization method with consideration of emergency disconnect case, etc.)
Also, MH21 conducted studies from the economic viewpoint using the production simulator and the economic evaluation program on the methane hydrate resource field selected in the eastern Nankai Trough area. These studies have indicated possibility of economic feasibility to be realized through studies continued into the future. Also, MH21 extracted technical issues from the viewpoint of improvement of economic performance (such as higher productivity, improved recovery rate, etc.)
MH21 conducted collection and compilation of basic information required for predicting environmental impact in methane hydrate exploitation as well as studies on technology elements.
MH21 conducted environmental investigation of the sea area for grasping basic information concerning the sea area hosting methane hydrate resources and studied the ground properties of the sedimentary layers beneath the seafloor by using core samples from an MITI exploratory test well. Furthermore, MH21 extracted environmental factors to be given particular considerations in methane hydrate exploitation, that is, methane leakage and ground deformation, created a model for predicting their behavior and developed sensors that would enable real-time monitoring of offshore production tests.
In FY 2005 and FY 2008, project evaluation was conducted by external well-informed individuals according to the METI guidelines for technical evaluation. In the evaluation given in FY 2008, at the end of Phase 1, it was recommended to proceed to Phase 2. The following summarizes major opinions and suggestions given in the FY 2008 project evaluation.
- This project is in line with the national energy policy, greenhouse gas reduction policy and ocean policy, and also helps satisfy the needs of the people from the viewpoint of securing of energy resources, attracting great interest and expectation. As for the accomplishment of the researches in Phase 1, the goals were virtually fully accomplished through extension of the period and other flexible efforts, which is to be highly appreciated.
- While certain achievements have been brought about in Phase 1, the project has not yet reached at a level where the private sector may consider participation with further technical or scientific challenges yet to be solved before commercialization, including the need for additional technological development and application and development of existing technologies. Therefore, it is appropriate to promote this research and development project under the initiatives of the state.
- As the goals of Phase 1 have been mostly accomplished as the research outcome has shown, it is appropriate to proceed to Phase 2. Note that it is difficult to evaluate the validity of commercialization at the present stage when the basic research is completed. It will be premature until MH21 sees the outcome of Phase 2.
- In offshore production tests in Phase 2, first of all, it is necessary to obtain adequate measurement data concerning the impact on the surrounding sediment layers as well as the maximum production ratio of a single well.
- In the future, it is important to cooperate with organizations and advanced companies around the world to facilitate efficient progress of the project. In order to facilitate international cooperation, MH21 needs to develop a basic strategy through reconfirmation of what resources (technology and funds) Japan has as well as understanding of its partners’ capacities and positions.
- In the future, MH21 will definitely be faced with an increasing number of practical challenges as the project is further directed toward goals such as verification and commercialization and grows in scale. It will be necessary to clarify and/or redesign the targets in a flexible manner while fully examining results obtained step by step. In particular, it is desirable to clearly set out the goals of offshore production tests in conjunction with case studies by simulation.
- In the future research and development project, MH21 needs to prepare itself by extensively mobilizing engineers and other staff members from a broader range of areas. Also, it is important for the organizations responsible for the implementation of the national project to conduct detailed studies concerning environmental measures as well as to assume due accountability toward the public.
- Efforts should be made to bring about added effect by incorporating a broad range of related technologies, besides technologies specific to the area of oil and natural gas.
- Efforts are called for clear indication of unique classification and definitions according to the characteristics of hydrate, and for presenting such definitions as the world standards. Understanding among the general public and parties concerned is likely to be deepened along with clear representation of this development effort as a project focused on methane hydrate that has the highest potential for successful exploitation (within the country) among the categories under such classification.
- In order to move toward commercialization, it is necessary to encourage active participation of private oil and gas development companies with operating experiences and technologies.
Future Challenges based on Accomplishment of Phase 1
While the accomplishment described above has been obtained from the studies carried out in Phase 1, there are a number of technical issues to be solved before realization of future commercial production.
(1) Evaluation of methane hydrate distribution in areas other than the eastern Nankai Trough
In Phase 1, MH21 grasped the state of methane hydrate occurrences in the eastern Nankai Trough area and established technologies, among other things, for identifying methane hydrate concentrated zones. Based on the findings from the assessment of the resource amounts in the eastern Nankai Trough, MH21 needs to expand the target area to areas off the coast of Japan other than the eastern Nankai Trough to proceed with estimation of distribution of methane hydrate concentrated zones.
(2) Implementation of longer-term production tests
While MH21 succeeded in continuous production of methane gas from methane hydrate-bearing layers by the depressurization method in the onshore production tests in Canada, the duration was for six days. Therefore, longer-term production tests are needed to further verify issues related to long-term productivity of methane gas production from methane hydrate-bearing layers as well as its production behavior, production damages, etc.
(3) Implementation of offshore production tests
Japan can only find domestic methane hydrate resources off the coast of Japan. Thus, it is essential to develop technologies that enable safe and economical production of methane gas from methane hydrate-bearing layers, which necessitates offshore production tests. As these tests should be conducted in deep-water shallow formation zones, it is necessary to address technical issues involved and develop preliminary environmental impact assessment and then to prepare test planning to ensure safe implementation of the plan. Also, MH21 needs to verify gas recovery methods and production methods focused on methane hydrate-bearing layers off the coast of Japan and extract technical challenges.
(4) Investigation of advanced production methods and optimization of the development system
In addition to field production tests, in order to produce/recover methane gas from methane hydrate-bearing layers in economical manners, efforts for ensuring ultimate cost-effectiveness are needed toward technological sophistication that enables efficient production. For this purpose, MH21 needs to develop recovery and production methods for improvement of productivity and recovery rate of methane gas as well as examination of drilling/development systems for higher cost-effectiveness.
(5) Grasping of environmental impact and establishment of the assessment method
While environmental impact is likely to arise from methane leakage, seafloor instability including landslides, etc., specific environmental assessment methods are yet to be established. On the other hand, Phase 1 has yielded geological findings concerning methane hydrate concentrated zones along with a direction of studies for production methods. Thus, it is now possible to investigate specific risks concerning environmental assessment accompanying hydrate resource development. For that purpose, it is necessary to study issues including extraction of environmental risks in offshore production tests, identification of characteristics and countermeasures. Also, MH21 needs to obtain data concerning seafloor environment required for such studies and to grasp environmental impact through actual monitoring of environmental impact as well as to establish the method of environmental assessment, looking to realize commercial production.