More than 40 years have passed since the exploration and development in Bohai Bay Basin, with increasing exploration degree. Nowadays, exploration targets become increasingly subtle, and more difficulties need to resolve in exploration process. Facing these challenges, new ideas and new technology or method will be used for us to enhance pre-exploration in different regions. In recent years, important breakthroughs have been made in beach exploration, onshore lithologic-stratigraphic oil-gas reservoirs exploration, accurate exploration in mature areas, deep buried hill and volcanic oil-gas reservoirs, and etc. Nearly 800 million tons of oil resources have been discovered and proven. Based on comprehensive analysis, it is suggested that the large potential of oil/gas still exists in Bohai Bay Basin. Petroleum-rich sags, as major targets for future exploration, include frontiers such as beach, lithologic oil-gas reservoirs, deep buried hill and volcanic oil-gas reservoirs and the mature areas, which will lay a solid foundation for an annual increase of 100 million tons of oil from PetroChina Blocks, Bohai Bay Basin in the long period of future.

Based on the resources potential in the west region of southern Songliao Basin, its exploration fields can be divided into downwarping tectonic-sequence and fault-depression tectonic-sequence units,in which the major exploration targets of downwarping tectonic-sequence include both tectonic oil-gas reservoirs such as inverse tectonic belt, slope low amplitude structure group ,and nontectonic oil-gas reservoir such as stratigraphy and lithologic reservoirs .While themajor exploration targets of fault-depression tectonicsequence include conventional natural gas and non-conventional natural gas reservoirs.Therefore, it is put forward that stratigraphic - lithologic reservoirs in this area would gradually become important targets for exploration, and pointed out different techniquemeasures would be taken to explore different-order objects .

The depth of Quaternary and Pliocene source rocks deposited in Huhe depression, Hetao Basin, ismore than 1200m, in which the content of organic carbon (OC) averages 0.59%,and organicmatter includes mixing and humic types, source rocks are immaturity and have the ability to generate much gas. The air bubbles emitted from many hydrologic shallow wells can confirm the existence of biogenic gas.The reservoir rocks consist of shallow-and half-deep lacustrine facies silty-fine sandstones, argrillaceous silty sandstone, with low diagenesis and relatively loosen rocks, so the porosity of reservoir is usually more than 20%, reulting in high-quality reservoirs. Mudstone, mirabilite and humic soil developed on the Quaternary section of 150-300m, which has relatively high sealling feature and it can become ideal cap rock.The concentration of biogenic gas ismainly controlled the trap. By contrasting, it is found that the accumulation condition of biogenic gas in Hetao Basin is same as that in Qaidamu Basin, it has a potential of gas resources and promising prospects of exploration.

Through summarizing the exploration history of Halar basin, it is discussed the exploration of fault-depression basins have four features, including (1) lots of investment input for exploration at early stage and long time to prepare before making exploration breakthrough;(2) the positive correlation between exploration engineering quantity and exploration results;(3) expanding 3D seismic exploration while resulting in new discovery of basin exploration results; (4)resources to be understood varies largely with different stages of exploration .After analysis the three stages of fault-depression exploration including the prepare stage for seismic survey, systematic study and accurately making location of a well,as well as increasing the quantities of 3D seismic and drilling works,and exploration from discovery to breakthrough ,it is concluded that the engineering quantity can ensure the breakthrough of exploration, 2Dseismic is the base of exploration discovery and 3D seismic is crucial to exploration breakthrough, the resources of fault-depression basin has close relation with drilling degree.Accoding to themodel above,it puts forward that themedium-small basins such as Sanjiang basin,Dayangshu basin,Yilan-Shulan basin,Sunwu-Jiayin and etc. ,which all locate at periphery Daqing Oilfield, have better prospects for exploration.

Huahai sag is a small sedimentary fault-depression basin formed during Mesozoic-Cenozoic periods, its accumulation conditions of oil and gas represent the characteristics of medium-small basins.Through analysis on the geological factors of petroleum system, the results indicate that the Cretaceous source rock,deposited in the depocenter of southern Huahai sag, has a potential of hydrocarbongenerating and capping ability , the physical property of reservoirs are bad in general,but the margin of the sag lack oil-generating and conservation conditions . As seen from the time configuration of various reservoiring factors , the later of early Cretaceous is the principal phase of petroleum migration and accumulation in the sag centre ,mainly forming small oil reservoirs by short distance accumulating.In Tertiary,oil and gas migrated and accumulated again, as well as locally regulated ,being affected by structure activity. The analysis result reflects that Huahai sag has a less potential of exploration, it is ,therefore,suggested that the further exploration should be focused on looking for small oil reservoir in the sag ,and the central tectonic belt ,located in hydrocarbon-generating center , will be seen as the major targets to be explored.

Although Jiyang Deperssion has been explored for 40 more years, it now is in the exploration stage for subtle oil reservoirs, and still holds rich remaining oil resources.By predicting with multi-methods, the proven oil reserves in Jiyang Deprssion will be seen to be increased steadily over coming decade,among incremental reserves, the reserves from the subtle oil reservoirs such as lithologic reservoir ,the Tertiary strata and buried hill and etc. will become the principal part.To ensure the stable increase of proven oil reserves, it must adopts some measures related to exploration

Based on the characteristics of proven oil reservoirs in Baiyinchagan depression, analysis on the control factors of oil and gas reservoir-forming including tectonic evolution, structure style, sedimentary and source rock reveals the regularity of hydrocarbon enrichment, i.e. oil and gas reservoirs controlled horizontally by themain source sags distributesmainly in the periphery of hydrocarbongenerating sags, especially being enrichment in the southern and northern slopes ; in vertical ,oil and gas reservoirs distribute in the 1st member ofCretaceousDuhongmu Formation and Tenggaer Formation. Petroleumaccumulation ,highly controlled by structure background, concentrated on the two sides ofmajor faults.Structure noses, fault block and fault-anticlines are the main structure units to form oil and gas reservoirs.

Delphi forecasting method has been used to choose the key techniques of petroleum geophysics,which consist of 5 core techniques such as the seismic collecting technique in complicated region, imaging technique of complicated structure, predicting technique of complicated reservoirs, seismic technique of oil-gas fields development ,as well as the R & D of seismic collecting data processing and interpreting software, these techniques are coincided with the situation of our country. The strategic significance, technique difficulties and appliance prospects of various core techniques have been demonstrated systematically, and it has rationality and necessity to form and develop these techniques. This research result has caused better effect in the practical application.

Based on the features ofmudstone with higher gamma ray than sandstone in sandstone -mudstone section,we can distinguish sandstone reservoir from the drilling profiles with gamma ray log.But this method is not reliable ,for instance,when the clay types change or sandstone reservoir contain some high radiation elements ,the gamma ray value of the reservoir is usually high,resulting in mistaking the sandstone reservoir with high gamma ray for mudstone one.ECS (Element Capture Spectroscopy)logging can effectively distinguish this kind of sandstone reservoir through measuring different elements capture spectroscopy of strata

The inversion method of reservoir prediction, based on acoustic wave (AC), has been applied to find permeable sandstone in tuffaceous conglomerate and sandstone , and its predicting result is not ideal. Being used the inversion method based on porosity of reservoir, the prediction precision has then been increased. Meanwhile, the analysismethod of attribute property is also used to identify high quality reservoir ,as a result, two favorable sand bodies has been predicted, one of them has low-production oil flow after oiltesting, which makesmature oil-producing wells in this area revivify .The method can be used in reservoir predicting in other regions with similar geological condition .

With the fast development of information technique, it is introduced the necessity to build information platform of oil-gas exploration and production. By combining the database and internet technique, it puts forward that the developing tendency and goals of oil-gas exploration information platform, i.e. the platform how to organize, process and deliver data resource of exploration information, to make data resource input database and other related units share to be authorized, meanwhile it can realize the data statistics, processing and formation of annals and menology. How to application and inquiry of exploration information on the platform has been particularly discussed.. The information platform has certain practicability and economic benefit in oil-gas exploration and production, and it can be worth to manage information for the exploration and production units

This paper analyzes briefly the tectonic evolutionary history, the texture and petroleum systems of salt-bearing basin in Gabon and its adjacent area, focusing on present situation of petroleum exploration in the basin and major oilfields, especially Rabi-Kounga and Anguille Marine oil fields. It points out that there are nine prospect belts of petroleum exploration in salt-bearing basin in Gabon and its adjacent area, with the large potential of petroleum exploration

Abstract:Latest exploration examples in recent years show that the economic benefit of subtle oil-gas reservoirs exploration is increasing, which is even more than that of conventional structural traps. Based on the classification of subtle traps in the world, they are divided into three types, namely lithologic-stratigraphic trap, hydrodynamic trap and composite trap.While lithologic-stratigraphic trap can be subdivided into three basic styles, including sedimentary trap, diagenetic trap and interface trap. At the same time, the development status of exploration technology on subtle reservoir is introduced from four aspects such as geology, geophysical survey, drilling and well log.