A total of 636 exploration wells and appraisal wells in Yanchang block were brought under survey to predict thickness and distribution of dark mudstone of coal measures and coal rock. The purpose was to clarify the distribution characteristics and sourcing potential of dark mudstone of coal measures in Upper Paleozoic Benxi Formation to Shanxi Formation in Yanchang block of southern Ordos Basin. It is concluded that the northeastern part of Yanchang block is the main abundance area of dark mudstone of coal measures and coal rock. Meanwhile, a series of samples from more than 20 exploration wells and appraisal wells deployed in the block were acquired for indoor analysis and source rock appraisal. The analysis indicates that dark mudstone of coal measures in Benxi Formation and the second member of Shanxi Formation is high in organic matter abundance, mainly humic (type III). Organic matter is under the high-mature to over-mature stage. Finally, this paper makes a comprehensive analysis of reservoir and drilling results and comes up with the near-term exploration direction according to appraisal of source rock and on the basis of the calculated sourcing strength of Upper Paleozoic dark mudstone of coal measures in Yanchang block. Therefore it is of an important guidance to natural gas exploration and development at the next stage.

Permian Wutonggou Formation in Jimsar Sag of Junggar Basin has a potential for upgrading of reserves and progressive expansion, but its distribution scope of favorable reservoirs and characteristics of vertical variation remained unclear. Wutonggou Formation is the stratigraphic record of Jimsar Sag deposited predominantly by the rising semi-cycle and subordinately by the falling semi-cycle during the intermediate base level cycle. The large-scale braided delta plain subfacies and frontal subfacies developed in the study area at the initially rising stage of the intermediate base level cycle. The lithologic characters are gray sandy conglomerates and gravel sandstone mainly in coarse grains with a medium to large thickness. The braided delta plain subfacies basically disappeared in the middle and later period of the intermediate base level cycle. The sedimentary scope of frontal facies dwindled gradually while the reservoir layers became thinner. The subfacies is mainly coarse and fine sandstone of medium to thick layers. The thin-layer fine sandstone and siltstone of shore to shallow lacustrine subfacies developed in the falling stage of the intermediate base level cycle. The reservoir rocks of Wutonggou Formation are classified into the types of II, III and IV according to the criteria of Permian rock in Junggar Basin. The reservoir quality of lower member of Wutonggou Formation is better than that of upper member. The favorable reservoir sand bodies are distributed in eastern slope zone, slope near-shore zone and northeast zone of Jimsar Sag.

The weathering crust reservoir developed on the top of Triassic Leikoupo Formation in Chuanxi depression. Recently, a high-yield industrial gas flow was acquired from Well PZ1 drilled at this weathering crust, indicating a great oil and gas potential of Leikoupo Formation, but the failure of Well TS1 also shows complexity of the gas reservoir. The grained dolomite with dissolved pores is the main reservoir in the 4th member of Leikoupo Formation in Chuanxi depression. Based on the dolomite flat, the high-quality reservoir came under dolomite diagenetic transformation in the later period. However, thanks to interferences of faults and gypsum in Leikoupo Formation, it is difficult to predict reservoirs by means of seismic reflection structure. The study indicates that the top of Leikoupo Formation in Chuanxi depression is characterized with unique fault facies. Two small arc-shaped fault belts developed in the depression, which are dolomite with strong fault deformation facies. The complete anticline with the faults undeveloped was behind the fault belt and in the form of dolomite with weak fault deformation facies. The eastern slope of the depression is crumpled gypsum facies. Based on the unique characteristics of fault and geo-mechanical principles, the two small arc-shaped fault belts are predicted as rigid formations with the single layers being thin and dolomite flat marginal facies. The layers of reservoir are relatively thin but with development of fractures. The complete block behind the fault belts is the rigid formation with the single layers being thick and dolomite flat central facies. Thickness of the reservoir is large. The crumpled zone east of the small fault belts is gypsum development zone.

Igneous reservoir has become an important oil and gas exploration area in Liaohe Basin. Three unique items of key technology have been developed for exploration of igneous reservoirs on the basis of exploration study and practice in the past few years. (1) Technology for evaluation of igneous reservoirs determines the exploration direction. The Es3 formation in the main stage of basin development is the major stratum series of igneous oil and gas exploration. Near-source accumulation determines the main zones and belts for oil and gas exploration. The favorable lithology, lithofacies and fracturing transformation zones are the exploration target of effective reservoirs. (2) Technology for identification and prediction of igneous igneous rock body confirms exploration targets. Attributes – inversion joint seismic identification confirms the distribution scope of igneous rock body while igneous lithofacies seismic identification and description predicts the favorable distribution zone of lithofacies. Integrated geological-logging identification helps determine the type of igneous rock and identifies favorable reservoirs. (3) Technology for transformation of igneous reservoirs effectively improves producing reserves. The ^“large displacement, low sand ratio, high strength and multi-stage plug fracturing^” process for transformation of igneous reservoirs substantially improves productivity and ensures success rate of oil and gas exploration.