The Ordovician carbonate reservoir in Block Ha 6 is characterized by karst fracture-cavern in buried hill. The reservoir space includes visceral cavity, burrow pore, intragranular dissolution pore, moldic pore, faults, fracture, cave system and collapsed cavern-ceiling crackle system. In this paper, series models were built on the basis of collapsed cavern-ceiling crackle system in Block Ha 6, fracture-cavern model, well logging-seismic integrated model, seismic forward model, and reservoir model were developed. "Moniliform" reflection of seismic was actually great collapsed cavern and fracture, but the subsurface river system could not be recognized effectively by current seismic technology. Ceiling crackle was defined. The ceiling crackle caused by top cave collapse was main oil and gas production interval in Block Ha 6. Secondly, the break-out dome was also oil and gas production interval; oil and gas could be produced through ceiling crackle. Therefore, the concept of ceiling crackle was very important to well drilling, well logging, acid fracturing test and production test

Through more than 20 years' exploration, a variety of hydrocarbon reservoirs were discovered in Beir sag, Hailar Basin, including the structural hydrocarbon reservoir, the structural-lithologic reservoir, the structural-stratigraphic reservoir, and the buried-hill reservoir. Vertically, oil and gas are mainly distributed in buried hill in basement, Tongbomiao Formation and Nantun Formation, and small amount of hydrocarbon indication was seen in the strata of Damoguaihe Formation. Horizontally, oil and gas are mainly distributed in the hydrocarbon-generating secondary sag, and its surrounding fault zone and buried-hill zone, as well as the lithologic sand body near it. Formation and distribution of hydrocarbon reservoirs in the sag are mainly determined by hydrocarbon-generating secondary sag, the fault zone, unconformity and sedimentary facies.

TheWanchang Formation and Qijia Formation in Liangjia shallow reservoirs of Chaluhe fault have always been concurrent exploration horizon. As evaluation and deployment was intensified unceasingly, a series of hydrocarbon reservoirs with shallow depth and good benefit were discovered successively. In the past two years, overall study and deployment was carried out on Liangjia shallow reservoirs. Hydrocarbon reservoirs here were mainly controlled by faults and lithology, based on comprehensive analysis of the correlation of the structure, sediments, and reservoirs and the hydrocarbon accumulation in the studied area. It was confirmed that the first member of Wanchang Formation featured in co-production of oil and gas, simply oil production, simply gas production, and thorough development in whole area, while the first member of Qijia Formation was dominated by oil where oil and gas were mainly distributed in Block Xing 19-3. The first member of Qijia Formation was confirmed as a benefit block that could be developed and produced recently. This was of instructive significance to deployment of overall development and productivity construction in the block.

Lacustrine carbonate rocks are widely distributed in the lower part of the first member of Shahejie Formation of Palaeogene in southwest margin of Qikou sag. Comprehensive analysis revealed that it had favorable accumulation conditions, good space configuration of source-reservoir-cap rock associations. Oil shale and dark mudstone stably distributed in the lower part deposited with carbonate reservoir interactively, and they were both source bed and favorable regional cap rocks. This was favorable for large-area accumulation of carbonate reservoir and owned certain potential for exploration. Currently, oil and gas discovered through exploration are mainly distributed in fracture development belts and fold deformation zones, which proves that hydrocarbon accumulation is closely related to the degree of fracture development, and reservoir types are mainly structural-lithologic ones. This paper pointed out that exploration should be mainly carried out in the fracture development zone and the transitional zone of dolomite and sandstone, based on strengthening engineering technology research. And plane fracture prediction should be conducted in carbonate reservoirs in these areas without fractures

Lots of exploratory wells were drilled around the slope zone of Structure 428 in the past two years, and significant discoveries were made in Paleogene reservoirs. However, the structural trips for next drilling and exploration were very limited. In order to clarify the exploration potential of the area, comprehensive study was done on regional structure-sedimentary evolution features, from the perspective of regionalstereoscopic exploration. The control of structural evolution to sedimentary patterns and their distribution range was analyzed, and its effect on hydrocarbon accumulation was also discussed. On the basis of establishing regional sedimentary patterns, the hydrocarbon reservoir accumulation regulation of the area was clarified. It was believed that a large scale structure-lithologic hydrocarbon reservoir existed under the second member of Paleogene Dongying Formation, and oil and gas was mainly controlled by the development situation and distribution range of reservoirs under regional mudstone cap rock. The establishment of the sedimentary pattern god rid of the constraint of the idea of pure exploration of structural reservoirs. It was proposed that the exploration idea of structural-lithologic reservoir be set for the slope zone of Structure 428. The establishment of hydrocarbon accumulation pattern expanded the exploration potential of the area and provided technical support for next overall exploration evaluation of hydrocarbon reservoirs in the area

Dawanqi Oilfield is a light oil-based oilfield. The concentration of biomarkers and the abundance of neutral nitrogenous compounds are comparatively low that make it difficult to reveal the crude oil migration characteristics. Research shows that, commonly, there is a kind of compounds with high thermal stability in oils of Dawanqi Oilfield. They are the diamondoids, including diamondoid and bidiamondoid hydrocarbons. Chromatographic analysis indicates the compounds with different structure have great discrepancy in their chromatographic retention behavior. According to the similarity of chromatographic retention behavior and stratum chromatographic effect in principle, the oil fractionation effects of Dawanqi Oilfield during migration have been studied by using the ratios of diamondoids with different chemical structure. The results show that the migration parameters based on diamondoids have obvious distribution law. In general, the migration parameters of diamondoids increase as the buried depth gets shallower. The results indicate that crude oil migrates vertically. The migration parameters of diamondoids are low in areas near deep faults. The migration parameters of diamondoid increase from south to north far from those deep faults in the plane. All these show that the main migration direction of the crude oil in Dawanqi Oilfield is from south to north.

It is the clay minerals that distribute widely in the key gas-bearing reservoirs of the 8th Member of Shihezi Formation and the 1st Member of Shanxi Formation in the Upper Paleozoic of Sulige gas field. The content change of clay minerals influences the pore structure features, initiates the reservoir sensitivity, changes the reservoir seepage ability and affects the gas productivity in Sulige gas field. Through studying the characteristic of clay minerals and reservoir sensitivity, it can be concluded that core permeability is influenced by water-sensitivity, acid-sensitivity, stress-sensitivity, speed-sensitivity, and salt-sensitivity by turn from the strong to the weak. It is the water-sensitivity and acidsensitivity that are the most harmful to reservoir. At the same time, corresponding measures for reservoir protection and reconstruction are proposed. For example, it needs high sand ratio and low fracturing fluid during the course of fracture technology for water-sensitive area. Attention should be paid to acid-sensitive injury to reservoir of chlorite enrichment region. For improved acid-sensitive reservoir, rational prepositioned acid fracturing technique could be adopted to carry out reconstruction, enhance permeability and increase single well productivity

In the case of more and more serious energy crisis, along with the deepgoing petroleum & gas exploration and development, it is desired urgently for the exploring technology for fractured reservoir. The fractured reservoir is built up mainly by structural fracture, so structural fracture estimating is very important. And the tectonic stress field modeling is the most available approach for structural fracture estimating. The modeling with the elastic-plastic increment mode not only can model approximately the plastic deformation of geologic body, but also can consider the nonuniformity of the geologic body, so the modeling under the regional geologic evolution will indicate more closely the tectonic intensity. The modeling results in Dongying Formation in the eastern limb North Dagang Structural Zone show that the shearing stress distribution can accordingly indicate the petroleum assembling locations, so it is estimated that there is a meridional structural fracture developing zone in the middle of the eastern limb of the North Dagang Structural Zone, which will be the advantageous exploration target in future.

Currently, the amplitude and waveform information of seismic data are increasingly applied to the identification and evaluation of lithologic trap. The requirement of relative amplitude preserve of seismic data is higher and higher. But the techniques and flow of seismic processing mainly focus on structure imaging, and its effects on amplitude are often ignored, so the processing results are often badly amplitudepreserved. Based on real and model data, this paper analyzed the characteristics of amplitude preserve of surface wave suppression, geometrical spread compensation and predictive deconvolution techniques. On the basis of amplitude-preserved analysis, optimized processing methods and flow were proposed. The result showed that the amplitude features of seismic processing results could be preserved better

Oil and gas is abundant in Carboniferous and Devonian Mud of Upper Palaeozoic in Central Asia. Analyzing the regularity of oil-gas formation and distribution at Upper Palaeozoic in Pre-Caspian Basin and Chu-Saryus Basin in Central Asia indicated that oil and gas enrichment zones at Upper Palaeozoic were related to huge fractures and fluids coming from deep of the earth. Interdependency and interaction between deep structures of the earth and sedimentary seal resulted in the enrichment. Predecessors regarded that oil and gas distribution and enrichment in Carboniferous was under control of the distribution of Carboniferous source rock, structure background and volcanic lithofacies zones. Besides, Central Asia is close to Xinjiang, and its geological structure is also similar to that of Junggar Basin. In comparison with the regularity of oil formation and distribution at Upper Palaeozoic, and considering geological features and current state of oil-gas exploration at Carboniferous in Upper Palaeozoic, it was considered that Carboniferous source rocks in Junggar Basin suffered from magmatic emplacement such as jet flow, and were intensively altered, leading to secondary hydrocarbon generation. The pattern of hydrocarbon generation inside volcanic rock is different from the traditional one. With combined action of materials from mantle and hot alteration of source rocks, it is believed that there would be great potential of hydrocarbon generation at Carboniferous in Junggar Basin

Block Sagizski in the Pre-Caspian Basin is rich in hydrocarbon, and 20 oilfields have been discovered successively, all of which are located in the Post-Salt strata. This paper analyzed comprehensively the elementary geology, features of oil geology, oilfield distribution, and hydrocarbon accumulation conditions of this Block. The analysis revealed that the Middle Triassic and the Middle Jurassic were the main horizon of hydrocarbon accumulation vertically; the reservoirs were mainly distributed around the large oil windows horizontally. The oilfields discovered in early years concentrated in the west of Block Sagizski, most of which were the Middle Jurassic and the Lower Cretaceous reservoirs on the top of salt swell, while those discovered in recent years concentrated in the east of the Block and most of them were the Middle Triassic reservoirs. This paper also pointed out themiddle Triassic strata on the salt eaves (the shoulder of the salt swell) had favorable hydrocarbon accumulation conditions, and they would be favorable exploration targets in the future

Owing to its abundant hydrocarbon resource, deep offshore region will become the important replaced area for future oil & gas reserves increment. Enacting appropriate exploration strategy is vital for the oil companies to decrease exploration investment, avoid drilling risks, and attain oil & gas discoveries ASAP. This paper took the deep offshore exploration region of the Middle Sudanese Red Sea as an example to make a systemic analysis to its geological configuration, petroleum geology conditions and influence factors for exploration activities. The results indicated that there were two sags and one salient in the deep offshore area; basement was pre-Cambrian igneous and metamorphic rocks and main sedimentary strata were clastics, carbonate and evaporates deposited during Miocene-Pliocene Red Sea rifting and drafting period. Two sets of source-reservoir-cap assemblages, i.e. above-salt and sub-salt, were formed in the region and Belayim Formation reservoir in the north sag was the most favorable potential target because of its good hydrocarbon generation & accumulation condition. The identification & reliability of sub-salt drilling prospects and the accurate geological & engineering risks prediction before drilling were key factors for offshore drilling. Improving the seismic imaging quality, re-interpreting and re-evaluating the sub-salt prospect configuration and finalizing the offshore drilling preparation were still the primary jobs for next exploration period.

Bangladesh is located in Southern Asian subcontinent, which is an important hydrocarbon district. Most territories of the country are covered by Bengal Basin. In recent years, exploration in the basin has been rising year by year, and many new discoveries were found one after another. According to the data, Bengal Basin has two effective source rocks. The source rocks of Oligocene Jenam Formation are mainly distributed in Surma Depression, while the maturation zone of source rocks in Miocene Bhuban Formation concentrates in northern Hatia Depression. The latter one is in lowmature stage and has limited hydrocarbon supply. Horizontally, oil and gas distribution is obviously affected by these two source rocks and traps; vertically, Miocene reservoir in the eastern of Foredeep Belt contains the majority of oil and gas. Comprehensive analysis showed that favorable exploration area of Bengal Basin was the eastern Foredeep Belt, and Miocene reservoir would be the hotspot and focus for next exploration

Through the analysis of oil shale samples of the 7th Member of Yanchang Formation, and combined with geological features of Triassic sedimentary period of oil shale in the south of Ordos Basin, it is believed that the rich oil shale of the 7th Member of Yanchang Formation was formed affected by paleoclimate, structure, and sedimentary environment.Warm and moist paleoclimate is conducive to improving the initial productivity of lakes in the sedimentary basin. At the sedimentary end of the 8th Member of Yanchang Formation, volcanic eruption events occurred on the west and southwest margin of the basin led to the formation of the sedimentary pattern dominated by deep lake of the sedimentary period of the 7th Member, which was favorable for enrichment of organic matter. Tuff bed generated from tuff particles produced by volcanic eruption at the bottom of the 7th Member of Yanchang Formation could insulate oxygen and be conducive to oil shale preservation. Oil shale developed in deep lake sedimentary environment is the thickest and has higher oil content, and is semi-deep and shallow lake facies. It indicates that the thickness of oil shale in the 7th Member is obviously controlled by sedimentary facies.

With the great development of CBM exploration technology, it is significant to enhance gas production rate as well as reducing development cost. Hancheng Block is now the main part of productivity construction of PetroChina CBM Company Limited. However, with complicated geological conditions and difficulties of exploration in the Block, it is necessary to focus on the research of CBM production techniques, in order to make a scientific and reasonable production system, thereby increasing the gas production rate. Based on pilot production and analysis on the wells produced over one year in Hancheng Block, this paper found out the factors controlling CBM well extraction effect in the Block, such as the interlayer interference, extraction intensity, and braise blocking. Then some reasonable suggestions are proposed against the controlling factors: 1) to make good control of the fluid level reduction rate to ensure the bottom hole pressure reduced slowly and steadily; 2) to choose the best layers to decrease the degree of interlayer interference; 3) to avoid the braise from blocking the formation by applying special fracturing liquid and using appropriate production facilities.