The Comprehensive Judgment And Recognition Research Of Chang4+5Reservoir In Yuan48Area Of Jiyuan Oilfield

In water-flooding of Chang4+5reservoir of Jiyuan oilfield in Ordos basin, oil wells haverapid response of water-flooding, and water-flooded is directional. Some oil wells present longflooding cycle and porous water breakthrough. Therefore, it is preliminary thought that cracksmay exist in the reservoir of this area. In order to perfecting pattern arrangement and makingreasonable development plan, the research of natural fracture comprehensive discrimination isurgently carried out.In this thesis, the research object is Chang4+5reservoir of Yuan48area. Based on theresearch of sedimentary tectonic setting and stress field of background, and comprehensiveutilization of geological data, core data, logging data and production performance data, wecarried out the following work. First, the research of the stratigraphic classification andcorrelation is carried out, and the precise stratigraphic correlation framework is established inthe study area. Second, the research of the sand top micro-structural features of small layer,sand thickness distribution characteristics, the sedimentary micro-facies of small layer iscarried out, and the characteristics of structure, sand thickness distribution, and sedimentarymicrofacies are described in the research area. Then, the limited coring wells are detailedstudied to establish the standard of the judgment and recognition of reservoir natural fractureof chang4+5in Yuan48area. And then, the suitable method of the judgment and recognition ofreservoir natural fracture is selected. On the basis of the single well fracture identification, andusing the multifarious methods, the predicting of natural fracture distribution characteristics iscarried out. Also, the result of the forecast is validated by using dynamic data. Finally, theinfluence factors of natural fracture is analyzed, and the preliminary analysis of the impact onthe development effect is carried on in the study area.The research shows that in the Yuan48area Chang4+5strata can be divided into theChang4+51, Chang4+52, and the Chang4+52can be divided into the Chang4+522andChang4+521. The total thickness of strata is about90m, and the strata thickness is basicallystable. In the study area, the purpose layer structure is simple and has the characteristics ofhigher east and lower west, also and some areas presents low amplitude uplift like nose. The distribution of sand bodies presents stripped along with the northwest to southeast, and thesand bodies of Chang4+522is thicker; The sedimentary facies of the study area is deltasedimentary, and the main sedimentary microfacies are underwater distributary channel,distributary bay,natural levee and mouth bar. Acoustic time of the R/S variable metric analysisin the study area shows that the higher value of fractal dimension, the higher degree of fracturedevelopment degree; The plane characteristics of permeability, permeability mutationcoefficient and contrast coefficient shows that in the development of natural fracture area thevalue of permeability, permeability mutation coefficient and contrast coefficient are bigger.Based on the acoustic time of R/S variable metric fractal dimension, permeability mutationcoefficient and contrast coefficient, it is better to reveal the distribution plane of naturalfracture. And the results show that the fractal in the west of study area is development andsmall in the east and south. The fracture direction is diversity, but the main direction isnortheast-southwest and nearly east-west. Using the dynamic data such as well test andinjection profile to verify the forecast results that shows the forecast technology has obtainedthe good prediction effect. The main influence factors of the natural fractures in the study areainclude the in-situ stress, lithology, thickness of sand body, sedimentary micro facies, and sandmicro-structure,etc.; Also natural fractures on the development effect has a certain influence.