Fine Characterization On Single Sand Body And Regular Study On Remaining Oil Distribution In The Ⅳ Block, Xinli Oil Field

In the process of oilfield development, most of the oil fields in our country has entered into high water cut stage, it makes the remaining oil distribution very complex. The remaining oil distribution, which has general dispersion and local concentration, is closely related to the genesis, connection and lateral changes of single sand body to guide the development of oil field. Therefore it has great significance to improve recovery factor through fine characterization on single sand body for the mode of remaining oil distribution.We start from the genetic model of reservoir with the theory of the sedimentlogy, structural geology, sequence stratigraphy, reservoir geology, logging geology and development geology, which based on domestic and abroad research. To analyze the causes, vertical and plane recognition as well as connective relation of single sand body, we use all kinds of data ranging from geology, seismic, logging, production to test. Describing the single sand body of delta reservoir in Fu Yu oil layer and the meandering river reservoir in Yang Dachengzi oil layer at Ⅳ block, Xinli oil field, we analysis the relationship between the isolation layer, interlayer, rhythm and the remaining oil distribution, which is mainly to predict remaining oil enrichment region for further developed suggestions. The main achievements are as follows:(1) Guided by the cycle contrast and graded control of high resolution sequence stratigraphy, we carried out the division and correlation of 309 wells in the whole region of the Fu Yang layers, which be subdivided into 5 sand groups,14 small layers of the Fu Yu oil layer,4 sand groups and 12 small layers of the Yang Dachengzi oil layer. Then Fu Yu reservoir was subdivided into 20 single-layers, while Yang Dachengzi is 15 single-layers further.(2) With the observation on the core analysis, we confirm the meandering river sedimentary with the surfaces of river, embankments, river flood sedimentary, and then further microfacies of marginal bank, abandoned channel, crevasse splay, sand sheet and alluvial flat in Yang Dachengzi layers. While delta sedimentary have subfaces of delta plain and delta front sedimentary, then further microfacies of riverbed detainment, crevasse splay and overflow bank sand, flood land and river flood and river flood swamp lake in Fu Yu oil layer Quan Ⅳ.(3) On basis of the isochronous stratigraphic framework of 61 profiles in which has the composite channel sand body of 26 small layers, we divide and dissect the single sand body combining with the analyze of sedimentary microfiches and dense logging curves in Ⅳ block, Xinli oil field. Then summarize the identification marks, analyze the genesis and establish the size of the single sand body.(4) We summarize the contrasting model systematically with isolated, docked, unilateral, multilateral, superimposed and multilayer type. The identification and contrast patterns in different sedimentary environment of single sand body show that in Quan4 is docked and multilateral type, locally with superimposed and multilayer type, while in Quan3 is isolated and multilateral type, locally is superimposed,docked and multilateral type, less in superimposed and multilayer type.(5) Combining with the interbeds of 309 Wells through Man-machine identification, we classify septal interlayer model to raise the reservoir architecture concept. Then we compile insulation distribution plane with the help of 3D septal interlayer model in QuanⅢ and QuanⅣ using petrel. Through the analysis of remaining oil saturation simulation, we define and further analysis the main geological factors as microfacies, river and interlayers distribution. Hitherto we summarize the pattern of remaining oil distribution:different microfacies, septal interlayer and complex remaining oil. And the study on plane and vertical of remaining oil distribution provides the basis for fine late oilfield waterflood development program.