Yearly production contributions of Enhanced Oil Recover y（EOR）are gradually increased since a number of oil reservoirs in the world are matured due to the production. Different methods have been applied to the various oil fields through continuous technology development. Thermal EOR such as steam injection to recover viscous oil has been a large contributor for a long period. While, many efforts have been devoted to apply chemical EOR to increase oil recovery, which might bring more efficient development with optimized chemical materials for the specific target field. Energy transition requires environmentally friendly EOR even under current lower oil price circumstances. Gas EOR, particularly CO₂-EOR is one of promising technologies to increase the recovery factor and also to store anthropogenic CO₂ to mitigate climate change. The paper reviews the trend and prospects of different EOR, mainly focuses on（1）CO₂-EOR and CCS,（2）recent advancement of chemical EOR,（3）Low Salinity Water Flooding（LSWF） as a new cost efficient approach. In addition, advances of nanoparticle-based EOR are briefly described.

We present the main reason behind two low-salinity waterflooding (LSW）coreflood tests, that failed to demonstrate promising EOR response. Repeating the coreflood tests using the acid-enriched oil and injecting the lowsalinity brine in the secondary and tertiary modes has led us that the total acid number (TAN）and the recovery mode appear to be the key successful factors for LSW in our carbonate system.

JX NOEX（JX Nippon Oil & Gas Exploration Corporation）has accumulated its expertise regarding Carbon Capture, Utilization, and Storage（CCUS）and Gas EOR through worldwide projects. The Petra Nova CCUS projecvt was sanctioned in July 2014 and the CO₂ capture and injection system was completed in December 2016, and followed by EOR oil production in February 2017. The hydrocarbon gas enhanced oil recovery（HCG-EOR）for Rang Dong Field, within Block 15-2 offshore Vietnam, started to be investigated from 2008 to maximize oil recovery. After the executions of feasibility studies, pilot test and installations of facilities, the project of HCG-EOR full field scale started in October 2014.

Three common issues have arisen after implementation of gas EOR operation in both projects;（1）sand production（2） back pressure increase by gas breakthrough（3）injectivity reduction. And the several countermeasures were put in place to manage these issues and to maintain stable oil production.

This paper presents the outline of the lessons learned from the actual operation of CCUS and HCG-EOR full field scale and the approach for further production optimization.

During the oil production process, oily waste water is coproduced at a rate several times that of oil. This water is known as produced water. Treatment levels and technologies are selected based on disposal method or reutilization objectives, environmental impacts, economics, and other such factors. For the treatment of produced water, the treatment system equipped with nitrogen microbubble flotation in conjunction with anthracite filtration and activated carbon adsorption was designed and examined.

Polymer flooding is being used as an enhanced oil recovery（EOR）method in Oman. The quality of polymer flood produced water（PFPW）is different from produced water（PW）without polymer, it was clarified that aluminum sulfate （AS）is more effective than poly-aluminum chloride（PAC）as a flocculant. Based on the examination results, a 50 m³/ day capacity pilot plant was designed, fabricated, and utilized to conduct produced water treatment trials, good oil removal was confirmed in all tests.

It was also confirmed that this accompanied water treatment water could be used as irrigation water for agriculture by performing necessary higher order treatment. As a result, it was considered that the development as a new water source in the Middle East, where water resources are scarce, could be expected.

We have researched the effect of micro-bubble CO₂ injection and its mechanism toward the practical application of micro-bubble CO₂ injection technology into Carbon Capture and Storage（CCS）and Enhanced Oil Recovery （EOR）. In the first stage, we have carried out laboratory experiments and examined injection methods and developed tools as basic research.

In the second stage, a field pilot test was conducted using a part of the Sarukawa oil field in Akita prefecture in order to verify the microbubble injection effect and mechanism evaluated based on basic research. In the test, the Huff and Puff method was adopted, CO₂ injection for 10 days and flowback（production）for 7 days were carried out. The test is carried out by microbubble CO₂ injection method and conventional CO₂ injection method, and the test period is one month each.

In the field test, the functionality of the tool was confirmed, that easy retrievableness in the well with slick line or wire line, the stable microbubble generation and injection, and the effect of the microbubble was evaluated as the improvement of CO₂ injectivity and storability. From the simulation model constructed based on the field test results, the mechanism of improving CO₂ injectivity and storability was also evaluated.

From these tests, it was confirmed that the microbubble injection technology can be applied in the field

Recently, activity of seismic survey is extremely reducing in shallow waters where marine traffic is busy and fishing activity is high. For example, in the northern part of the Tokyo Bay, no seismic surveys have been conducted since in the late 2000s. In December 2017, T/B Hiyodori of Tokyo University of Marine Science and Technology （TUMSAT）made a seismic survey using an underwater speaker, which is a non-explosive source with a relatively low environmental impact on marine ecosystems. As a result, a gas layer was detected as a low-velocity zone about 7 m below the seafloor. The subsequent investigations revealed that the gas was composed mainly of methane and the gas layer was widely distributed in the northern part of the Tokyo Bay. In addition to the widely distributed near-seafloor methane gas, a local accumulation of gas was observed as a so-called fault trap about 17 m below the seafloor. Total volume of the gases is unknown at this moment. However, considering the high flammability of methane, potential risks from the gases might be assumed from a viewpoint of disaster mitigation. Further seismic surveys are strongly required in the area.

A recent technology innovation is boosting potentials of chemical enhanced oil recover y（EOR） application to harsher field conditions, whereas it was possible for limited conditions under the past classic EOR screening criteria（Taber. et al. 1997）. To proceed with such a chemical EOR application, nobody doubts an importance of water management; however, most of the technical discussions focus on injection while lesser on production. Therefore, this paper recaps the recent innovation of chemical EOR and reminds the importance of water management from a viewpoint of production treatment in particular for realistic operatability. Finally, our current progress of technology acquisition is introduced with a brief roadmap plan.

Although Dr. Matuyama had made two significant achievements, the discovery of negative gravity anormalies in the Japan Trench and the proposal of reversal magnetism in the earth's magnetic field, he was also a pioneer in the field of geophysical exploration in Japan.

The Takamachi oil field, the first successful case of applying a gravity survey to petroleum exploration in Japan, is a typical field with rapid development and depletion due to over drilling, but some subjects on its petroleum geology including subsurface geological structure remain to be not resolved.