Effects Of Deep Fluid On High-quality Reservoirs In SD Structural Belt,Xihu Depression

There are mainly four oilfields called: CHX, CX, JG and TWT in SD Structural Belt,Xihu Depression,two aim formations of which called Pinghua Enocene and Huangang, has large potentials for exploration by preliminary exploration. This text combing with previous research results show that the zone in deep formation(more than 3000m) which development of low porosity and low permeability reservoir among which is probably to develop high-quality reservoirs. The main factor to formed high-quality reservoirs are development of a large number of secondary porosity. The high-quality reservoirs are which with high porosity, high permeability reservoir and better physical reservoir properties.SD Structural had occurred 2 times of magmatic activity which brought much hydrothermal fluid at the same time flowing to up through the pass ways such as deep faults, faults, reservoir permeability and unconformity and so on which made effect on reconstructing of sandstone reservoir, which left a sign which can be recognized at many aspects and caused better physical reservoir properties and the hydrocarbon source rock under the sandstone reservoir of Pinghu formation which with high thickness and high abundance of organic matter had a high potential for the production of organic acids. The important reason to formed secondary porosity is that: organic acids dissolved clastic grain especially feldspar. So to research effects of deep fluid on high-quality reservoirs in SD Structural Belt has a significantly important meaning.Making full use of the cores, well logs, cast thin sections, physical properties and organic geochemical characteristics data and so on and conduct comprehensive research, the results show that, main types rock with a higher feldspar are feldspardebris sandstone and debris- feldspar sandstone in study area where made a good premise to formed secondary porosity zone. There are two zones of high-quality reservoir one is lower of Huaguang formation the highest porosity is 35% average 23% anther is middle of Pinghu formation the highest porosity is 33% average 12%. High-quality reservoirs included both Type?and Type?reservoir in the study area. In the longitudinal, deep fluid transformation type of reservoir in Pinghu formation is worse than that in Hunggang formation, Type ? reservoir is main in the upper of Hunggang formation and Type ? reservoir is in the lower of Hunggang formation, while most of Type ? reservoir in the Pinghu formation or few of Type?and Type?reservoir. On the transverse the reservoir type in south of SD Structural is better than it in north of where.Basing on the previous research results combined with spectral data, analysis of inclusions show that improvement of thermal fluid to reservoir is not only reflecting on desolating rock skeleton but accelerating the release of organic acids in the process of thermal evolution of organic matter hydrocarbon generation of dissolution at the same time acidic thermal fluid itself can for dissolution of the reservoir, the benefits the advantages less than the disadvantages on the impact. Organic acids on reservoir performance on dissolution of feldspar and other silicon aluminate, of carbonate cement dissolution of carbonate and quartz dissolution, formation of intragranular solution pores, intergranular dissolved pore, and intergranular corrosion expanding hole and mold hole, improve the reservoir space, improve reservoir physical properties.