| The petroleum exploration effectiveness of Fu-huang exploration area is relatively low. With the further understanding of reservoir, the exploration breakthrough was got that the high-yielding wells was found in the west of Fu-huang exploration area from Chang6member of Yanchang formation and oil-bearing area was delineated revealing that the Chang6member of Yanchang formation has good exploration potential. In this paper, the Chang6member of Yanchang formation was studied based on the cross-section through the field, drilling core observation, the application of conventional core analysis of physical properties testing, casting thin and identification, particle size measurement, clay minerals X diffraction, heavy mineral analysis, zircon, scanning electron microscopy, cathodoluminescence, mercury and other technical means, the sedimentary facies, reservoir lithology, diagenesis and reservoir "four" relationship characteristics, physical characteristics and reservoir characteristics such heterogeneity were studied. And the comprehensive classification and evaluation of Chang6reservoir diagenesis was conducted by analysis of deposition sandbody; the distribution of oil and gas reservoir types and petroleum accumulation was analyzed to determine the physical properties of Chang6reservoir lower and to build up water discriminant map; the typical reservoirs were dissected; the reservoir controlling factors was discussed; the oil and gas accumulation was summed up and favorable target areas was preferred finally. The new views are as follows:1、The study area has the a mixed source characteristics(NE-SW, SW-NE),from Chang63to Chang61along the NE-SW trending provenance enhancement, Nancy-North East provenance weakened. And the sedimentary facies is dominated by delta front-deep lake, semi-deep lake and the reservoir space are underwater channel sand reservoir development and turbidite channel sand body.2、The rock type of Chang6was dominated by fine-grained feldspathic sandstone with structural and compositional maturity maturity lower interstitial material (mainly carbonates, clay minerals) uneven distribution of felsic overgrowth characteristics; diagenesis includes compaction, cementation and dissolution; porosity evolution of the thermal evolution of organic matter and clay mineral characteristics indicate that the evolution of this region has been entered in sandstone diagenesis stage A;3、Physical studies have shown that the porosity of the region mainly in the7.3%-8.3%, and permeability mostly between0.26-0.49×10-3um2) and the heterogeneity of sandstone reservoir is very strong with low porosity and low permeability;4、fine sandstone reservoir relative to other lithology, reservoir, oil well, lithology, physical property have certaincontrol effect on oil content; on the basis of relationship between oil layer loggingshow of oil and gas, natural GR-RT, AC-RT, determine thelithology the lower limit of Chang6oil reservoir of Yanchang Formation ofsiltstone, natural gamma limit86.9API, AC limit is226μs/m, the oil level limit of oilthe physical properties of the lower limit (7%porosity and permeability of0.15×10-3um2)was determined based test reservoir bit Sonic-resistance relationship and water discriminant plates was established.5、On the basis of a comprehensive classification of Chang6reservoir evaluation, the reservoir was divided into three categories (good, middle,bad),among which the good one is accounted for26%(Chang61),the others is15%(Chang62) and10%(Chang63)respectively.6、The distribution of hydrocarbon source rocks controls the enrichment of oil accumulation; sedimentary microfacies and reservoir physical property of reservoir distribution zone is mainly manifested in the control of the reservoir sand body distribution, reservoir space, lithologic trap of control; local tectonic setting controls petroleum migration&accumulation, showing the configuration of structure and sand body has the impact on petroleum enrichment:thin sand body and uplift structure could pray for the disadvantages of the reservoir property, if the sand body is favorable, this feature is not to reflected; diagenesis mainly controls the petroleum reservoir performance; and fracture takes double meaning for reservior accmulation,that is to say, it not only fomes migration channels,but also improved the permeability of reservoir performance, also would lead to loss of oil and gas.Based on the above, the favorable target oil-bearing areas was optimized optimization and a total of optimizing five areas favorable for type Ⅰ, nine areas favorable for type Ⅱ, and two areas favorable for type Ⅱ. |
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