| Fan delta sedimentary sand bodies are important oil and gas reservoirs,but the sand bodies usually have the characteristics of fast and lateral changes.In order to excavate and efficiently develop the remaining oil in the fan delta reservoir,it is necessary to study the reservoir structure.After years of water injection development,Chen Bao oil field achieved good results,but there are still a lot of residual oil in the reservoir,how to accurately determine the remaining oil enrichment area is now in urgent need to solve.Therefore,this paper takes the fan delta sedimentary reservoir of K2t13 sand in Chen Bao oilfield as the research object.Under the guidance of high-resolution sequence stratigraphy and sedimentary petrology,combined with core,logging and dynamic data,Based on the comparison,the stratigraphic framework is further refined,and the sedimentary system and subphase and microphase characteristics are defined.The characteristics of the fan delta reservoir structure are determined,and the distribution pattern of different microfacies in the fan delta and the remaining oil Of the distribution pattern.The main results are as follows:The stratigraphic development model of the study area is constructed by subdividing the stratigraphic layer from single layer to single level.According to the lithology and electrical characteristics,five auxiliary marker layers are identified,which are mainly composed of small-scale lake surface,which provides a new basis for stratigraphic contrast.According to the results of previous stratigraphic division,the small layer division scheme was modified,and 11 small layers were further subdivided into 21 monolayers.The sedimentary facies of the fan delta are identified,and the subphase development fan delta plain is associated with the fan delta front subfacies.According to the slope condition of sediruentary development,the fan delta plain is divided into steep slope fan delta and gentle slope fan delta.In the steep slope fan,the rock composition is complex,with the angular shape,the rock particle size is large,the difference is poor,the main hydrodynamic force is the gravity flow and the traction flow is the second.The steep slope fan delta is mainly developed braided waterway and diffuse sedimentary microfacies.The frontier is mainly composed of underwater distributary channel and estuary dam sedimentary microfacies.The rock in the gentle slope fan is mainly gravel,Round,mainly affected by the traction flow,followed by gravity flow.The gentle slope type fan plain is dominated by braided waterway and secondary waterway sedimentary microfacies.Using the method of vertical staging and lateral delimitation,the target layer is divided into levels.In this paper,we mainly study the interface of 3?5,the interface of 3 is the large-scale re-acting surface or hyperplasia surface in the large bottom,that is,the single-layer level;the interface of 4 is the interface of large bottom type,Interface for the large sand border,as the sub-interface;6 interface for the large-scale lake surface or unconformity,the equivalent of sand group interface.In this paper,three kinds of vertical stacking methods,independent type,superposition type and cascade type,are identified in this paper.In the lateral direction,four kinds of sand body boundaries are used to identify the relationship:braided channd?braided channel,braided channel?secondary river channel,braided river channel?estuary dam and other lateral boundary.The flooding degree of new drilling in the study area is analyzed,and the flooding level is divided into three kinds of flooding levels,which are divided into four flooding,weak flooding and flooding.On this basis,the remaining oil plane distribution map is based on 14 new wells.The results show that the distribution of residual oil is affected by the thickness of the gravel and the thickness of the mudstone,and the influence factors of different sub-sections are different.On the basis of reservoir structure,six kinds of boundary are identified,and the relationship between the boundary of configuration and the distribution of remaining oil is analyzed,and established the corresponding model. |
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