Logging Evaluation Of Super Heavy Oil Reservoir In MPE-3 Block Of Venezuela Oilfield

In the MPE-3 block of Venezuela,braided river deposits are developed,reservoir heterogeneity is strong,and crude oil is extra-heavy oil.Horizontal wells are adopted as the main development wells for the exploitation of extra-heavy oil cold production.Fluid distribution in the development process is complex.All these factors cause the difficulty of logging interpretation and the low accuracy of logging parameters.In view of the above problems,this paper combines the logging interpretation of vertical wells and horizontal wells in the study area to carry out the research and application of logging reservoir evaluation methods.For log interpretation of vertical wells,the "four characteristics" relationship of reservoirs is analyzed by synthesizing existing geological,core and oil testing data.A logging interpretation model of shale content,porosity and permeability parameters is established.Based on the interpretation of oil saturation and water saturation,aiming at the influence of poor fluidity of overweight oil on development,the parameters of immovable oil saturation and irreducible water saturation are interpreted by using the method of fitting porosity and permeability.The particularity of horizontal wellbore trajectory makes the principle of logging tools different from that of vertical wells,and logging curves are easily disturbed by many factors.Firstly,this paper carries out the analysis of horizontal wellbore trajectory and the influencing factors of logging curves,and then carries out the correction of horizontal wellbore curves.On this basis,the reservoir parameters of horizontal section are interpreted with vertical well interpretation parameters and models.The study area is a sandy braided river reservoir.The sand-body changes greatly and the understanding of the development of interbeds is not clear.By analyzing core data of coring wells and combining logging curves,the types and origins of interbeds are defined.The interbeds in the study area are divided into small interbeds,interbeds between sand bodies and interbeds in sand bodies.By using the method of core calibration and cross-plot analysis of GR-LLD parameters,logging identification criteria for different types of interbeds and interbeds are established.Give full play to the advantages of horizontal wells in the study area,analyze the logging response characteristics of horizontal wells drilling into formation interface,and establish a method of identifying layer interface and interlayer by horizontal wells,which provides effective support for the study of interlayer lateral distribution.On the basis of the above,the spatial distribution law of interlayer is summarized.Combining with oil testing data and logging curves,the characteristics of oil-water reservoir logging response are studied.It is found that the response characteristics of some dry layers and water layers are different from those of conventional dry layers and water layers.Aiming at this problem,the data of oil testing are re-analyzed and corrected in combination with coring and production data.It is considered that poor fluidity of overweight oil and strong reservoir heterogeneity are the reasons for inaccuracy of oil testing results.On the basis of this understanding,the discriminant analysis method is used to identify the super heavy oil fluids in vertical and horizontal wells in the study area by using 9 parameters,such as SP,GR,LLD,PHIE,VSH,PERM,SW,ratio of immovable oil saturation to oil saturation and permeability catastrophe coefficient Tk reflecting reservoir heterogeneity.Based on the above knowledge,the distribution law of oil layers in profile and plane and the influence of interlayer on oil-water distribution are studied.