The Gravity Flow Sedimentary Characteristics And Favorable Reservoir Evaluation Of The Yinggehai Basin Neogene

Based on the analysis of local sequence stratigraphy and sedimentary facies, gravity flow reservoirs (GFRs) deposited in Neogene in the Yinggehai basin have been discussed, including submarine fan in Dongfang area, canyon and axial channels in Ledong area. Those gravity flow reservoirs are formed in different provenance systems and slope types. Microfacies in different kinds of GFRs were classified and their distribution were studied according to intergration analysis of stratigraphy, sedimentology and reservoirs. In this research, a technical system for assessing high quality GFRs in the Yinggehai Basin was established. Through this study, the following main conclusions are made in the dissertation:1. Based on the comprehensive analysis of drilling, well logging, testing data, the high resolution sequence stratigraphy fromework was established in the Dongfang area of the Yinggehai basin. And sedimentary environments of those gravity flow reservoirs were identified.2. Two formation patterns of GFRs were pointed out based on the sediment supplies and slope patternes, one of them is the Lam River Delta-Dongfang Submarine Fan, which sediment supplies were from the Kunsong Uplift; the another is the Changhua River Delta-Dongfang Submarin Fan (northern Donfangl-1), which sediment supplies were from the Hainan Uplift. This result is very helpful for the exploration field of in the Dongfang Area.3. The Ledong canyon-submarine fan sedimentary complexes were identified, which sediment supplies were originated from the Kunsong Uplift. The canyon filling was clasified into3episodes in early stage and had a ’head’ where a continental margin delta developed from the Kunsong Uplift. The late contour current sedimentary hills vertically superposed on early canyon fills, sand body in this system superpose in the vertical and connect in the lateral. This find confirms characteristic of sources form the Kunsong Uplift, and indicates that different provenance systems and kinds of sedimentation presented in the Ledong area further. Among them, the Ledong canyon system, axial gravity flow channel, submarine fans, contour current drafts are the favorable exploration field in the Ledong Area. This research enriched sedimentary types in this area, extends exploration field in the Ledong Area, and helped finding more lithologic traps.4. A method to identify gravity flow and technology system of reservoir assessment has been established.5. An evaluating method for high temperature and high pressure (HTHP) reservoir was established, in which thickness and permeability lower limit values for high-quality gas reservoirs in the Yinggehai strata confirmed using inverse method from the radial flow productivity. Taking the porosity prediction experience formula as an initial model, correcting by regional rock types, secondary interstice and abnormal pressure parameters, a high-resolution porosity prediction technology was found.