Although Bohai Bay Basin has undergone through oil and gas exploration for over 40 years, its exploration is still in middle stage in general. On the basis of comprehensive analysis the exploration and research results onshore Bohai Bay Basin in 20th century, it is put forward that the following new ideas, i.e. Bohai Bay Basin might be a superimposed basin which was superimposed by Carboniferous-Permian coal-containing remained basin, Mesozoic rift basin and Cenozoic rift basin based on Paleozoic and middleupper Proterozoic craton; Dongshen large fault in Taihangshan Mountains controls the formation and distribution of oil-gas reservoirs distributed in the 4th member of Shahejie Formation , Kongdian Formation and pre-Tertiary; The geological structure of Tertiary oilgenerating sag controls the enrichment degree of oil and gas, and it is pointed out that it is key method for reserves increment to fined exploration for the Tertiary oil-generating sags, it is hope to explore the burial hill oil/gas reservoirs to ensure the bound increase of reserves.

The residual distribution area of Carboniferous-Permian in northwestern Jizhong depression, including Wen'an slope,Yangcun slope and Dacheng uplift, has sufferred from the later strong reconstruction of Indosinian-Yanshan and Himalayan movements as well as differential uplift-subsidence and pullapart-fault depression stages. As a result, the burial history in its east and west denuded belts witnessed uplift-subsidence-uplift and subsidence-uplift stages. However, the depositional systems of Carboniferous-Permian developed well, three types of depositional systems such as tide flat and swamp, delta and river can be identified from the bottom to the top , and the sandstone distributed in the distributary channels or braided channelsmicrofacies of delta and river depositional systems covered large areas ,widely distributed and deposited in a deep depth, and formedmain sand body types in this area. In the process of sandstone buried discontinuously and the reservoir diagenetic, especially, meteoric hypergene leaching process is an important factor to form the secondary porosity in sandstone reservoirs, the porosity degree is generally 15%~25%. Moreover, the deep meteoric leaching along fault surface may keep on improving the reservoir property of the areas developed with many faults, which formed the high quality reservoirs in this area. Based on comprehensive evaluation, it suggests that the west denudation belt should be themost favorable area for gas exploration

Through the research on the reservoir-forming conditions of complex fault-block oil reservoirs in Jizhong Depression, the results show that its reservoir-forming condition is relatively good. Themain factors that control the formation of oil reservoirs include structural setting, sealing feature of fault, oil-generation combinations, and sand body types etc. The reservoir-forming patterns include anticlinal type, sloping type, and multiple faulted type etc. But the large differences in control factors, enrichment degree and reservoir distribution each among these reservoir-forming patterns, therefore, much attention should be paid in the exploration of complex faultblock oil reservoirs.

Due to the double control of rock types and structures on oil reservoirs in Zhangdong area in Huanghua Depression, the pressure of sand formation distributed in different fault-block and that of different sand formation distributed in same a fault-block might be different. At that time, lagging drilling techniques resulted in heavy contaminated oil-layer of several wells and further increased the difficulty for oil-layer evaluation. By means of subdivision of sedimentary facies, determination of oil reservoirs, dividing the little research unit and the model to evaluate oil-layer, much attention has been paid to resolve the analysis of contradictory wells and conducted to fined evaluation for fine oil-layers, has achieved preferable effect. Its way of thinking and method can be valid for the fined reservoir evaluation with the complex geologic condition.

After an entire metamorphic basement was formed during the Late Proterozoic era, 4 large tectonic cycles have happened in Jianghan Basin, i.e. Caledonian, Hercian-Early Indosinian, Late Indosinian-Early Yanshanian and Late Yanshanian-Himalayian cycles, which resulted in a three-storey-type tectonic framework, which was superimposed by the open-sea basin of platform type before the Indosinian, the foreland lake basin during Indosinian and the intracontinental fault-depression salt lake since Yanshanian. The complexity of the tectonic-evolutionary process of Jianghan Basin demonstrates this basin is a reformed basin. This tectonic-evolutionary process also resulted in a complexity of active evolution for the essential geological elements of reservoir formation in the study area. Therefore, the complex tectonic evolution controls oil-gas migration and accumulation; and this process endow marine strata of Jianghan Basin with several characteristics, i.e. the long time and large scan feature for the oil/gas migration and accumulation, and the complexity of the law of oil-gas migration and accumulation. The reformed basin has a variety of reservoir-forming patterns including the earlier hydrocarbon generation-earlier reservoir formation, the early hydrocarbon-generating and late reservoir-forming, the late hydrocarbongenerating and late reservoir-forming , and secondary mixed-source patterns.Meanwhile,the structural evolution controls the exploration direction and target. The region marked by the earlier hydrocarbon-generating and earlier reservoir-forming is the promising exploration target for choice.

The method is provided for the favorable sandy reservoir's prediction by the recognition of the remained accommodation in this paper. Remained accommodation is the potential area of the geomorphic low near the surface of the sequence boundary during the period of the unconformity formation. The distribution of the paleocurrent is mainly controlled by the remained accommodation, the coarse sediments are transferred along the remained accommodation from the geomorphic high to the basin as the result of truncation, which are maintained in the area of the remained accommodation below the bypassing surface. As a result, the remained accommodation below the bypassing surface is the most favorable place for the high quality reservoirs to develop.Themethod had played a role in the prediction and high-effectiveness development of Sulige gasfield, and made a success in disposing wells in remained accommodation area over sequence surface. The application results show that the method of the remained accommodation recognition is an effective way for reservoirs prediction

Abstract:As one type of cements , laumonitide often develops in sandstone of Triassic Yanchang Formation in Ordos Basin and Jurassic Shaximiao Formation in Sichuan basin.Moreover the laumonitide is often dissolved by organic acid water to form lots of secondary pores. The practice of oil-gas exploration in Ordos Basin and Sichuan Basin confirms that secondary pores dissolved from laumonitide are major stored space of oil-gas. In the paper, with studying origin and distribution of laumonitide and the forming mechanism and distribution law of its secondary dissolved pore, it is considered that origin and distribution of laumonitide are controlled by sedimentary materials source and sedimentary micro-facies, and the distribution feature of secondary pores dissolved from laumonitide are controlled by the sources and migration pathway of organic-acid water

The tuffaceous volcanic reservoirs ofXing’anling group in Hailaer Basin, DaqingOilfield, includes andesite-rhyolite tuffaceous, andesite tuffaceous and trachy-rhyolite tuffaceous volcanic rocks. In the process of hydraulic fracturing, there are some problems to deal with, such as early sand plug, low return discharge rate and low success rate of fracturing. Through the experiment of rock hydraulic property and rock dynamics features research, it is put forward that the measures to be launched include: ① For tuffaceous,volcanic reservoirs with high-content clay, it is should increased the preventing dilatability of fracturing fluid, enlarging discharge capacity construction, in order to boost the net pressure of fractures;②For alkaline tuffaceous and ultra-alkaline tuffaceous reservoirs, it is should utilized the fracturing fluid to reduce filtration loss and enhance the preventing dilatability of fracturing fluid;③ For strong plastic tuffaceous reservoirs, it is should enlarged the discharge capacity

From 1998 to the present, a key technology research was carried into practice by PetroChina on petrophysics and well logging interpretation fro low-resistivity reservoir in themiddle and upper layer of Bohai Bay basin representatively and severalmature techniques are obtained: the reservoir geological condition of the low-resistivity oil formation distribution; clay additional conductivity - petrophysics experiment research on clay electric-chemical bound water; numerical simulation and time lapse logging research on the dual lateral logging and dual induction logging of different saturation oil-layers when saltwatermud or fresh watermud invasion; the corresponding low-resistivity oil-layer identification and evaluation interpretation methods. The important geological outcome has been achieved in Bohai Bay region and the west of China.

Aiming at non-obvious results achieved by seismic survey in complex mountainous area in Qaidam Basin for many years, in complicate mountainous seismic survey of Qaidam Basin, it suggests changing seismic strategic ideas to adopt a series of practical geophysical new methods, new technology and new method, such as adopting 3D design concept, using the method of wide line acquiristion, selecting operation tool flexibly, fined surface survey technology, high-velocity layer tracing lithology shooting technology, the technology of selecting line and point suiting local conditions, deep hole drilling technology in complicated area, imbedding geophone receiving technology, static correcting technology, the fundamental work are strengthened, the field operation are strict to launch, the ratio of signal and noise of single shot are greatly improved, the qualities of profiles are improved, and saw the good strategic results

By the research of the relationship among point-number, covering time, point-time of per length and per area, the ratio of onetime to full-time and engineering investment, it is suggested that the decrease of engineering workload—point-time in data acquisition is the key measure to increase the benefit of seismic exploration; cutting down of survey workload in seismic engineering and the drilling footages might be another methods to uplift the benefit of seismic exploration. With the rapid development of seismic equipments, the covering time becomesmore and more, when covering time reaches certain number, additional area would be regarded as the exploration area, and then point-time can be reduced, which is also a measure to raise the benefit of seismic exploration.

In 2002, PetroChina purchased the assets of Devon Energy Company in Indonesia, and started the operation of PetroChina Contract Blocks in Indonesia. Petroleum play analysis made new hydrocarbon-bearing formation discovered in the west part of the Jabung Block. New exploration interval and potential have been increased because of new commercial discovery. There are significant discoveries in the Bangko Block on the basis of analysis of trap types and their formation time. This achievement laid a foundation of remaining this block. CNPC will havemore interests to discover oil fields because that one of these partners had not take part in drilling West Piano-1 and Gambang-3. A series of reefs and structure traps have been found in the Salawati Island Block on the basis of comprehensive analysis of reservoir inversion and oil-gas check-up study, which resulted in a series of discoveries by drilling. Since 2003, PetroChina International Company in Indonesia has fixed 27 exploration-well locations on the basis of integrated research of petroleum geology and seismic-data particular interpretation. Up to the end of February 2005, 19 exploration wells have been drilled, 13 wells of which got discoveries, and successes of the exploration efforts have been achieved