Research On Fluid Evaluation In The Chad Buried Hill Bedrock Reservoir

Igneous buried hill reservoirs are widely distributed in the world,but because of the complexity of geological conditions,exploration is very difficult.The Chadian bedrock basin is a key exploration area for overseas oil fields.The lithology of this area is complex and the reservoirs are mostly low porosity and low permeability reservoirs.This study mainly focuses on the difficulties of well logging evaluation in buried hill reservoirs,systematically studies the Chadian bedrock buried hills,and forms a set of effective evaluation methods to solve the technical problems encountered in the actual production process.Firstly,combined with previous studies,the physical basis of logging response of buried hill reservoirs is summarized.Starting from the interpretation difficulties of lithology,physical properties,characteristics,reservoir evaluation parameters and evaluation methods,the reservoir evaluation is integrated with geological,logging,gas logging,testing and other data,and the related parameter interpretation model and reservoir evaluation method for complex reservoirs are established.Secondly,using the naming rules of core analysis in laboratory,the lithology of deep core intervals is calibrated on conventional logging curves,and the differences of log response values between different lithologic intervals are compared.The lithology identification of each interval is realized by crossplot technology.At the same time,the method of crossplot is programmed to realize the lithologic profile processing of the whole interval.On this basis,the porosity,saturation and permeability of the reservoir are calculated by using the physical parameters measured by core experiments as the standard and combining with the previous experience.According to the evaluation of buried hill inner structure,the inner structure of the whole section is divided vertically into weathering leaching corrosion zone,fracture cavity corrosion development zone,semi-filling fracture development zone and compact parent rock zone by using the data of electrical imaging and core photograph combined with geological classification method.The combination of logging and logging data is used to identify the fluid properties.It is found that the drilling parameters of deep resistivity and total hydrocarbon content in logging are sensitive to the fluid properties of reservoirs.The cross plot method can be used to effectively distinguish the fluid properties of reservoirs.Finally,through oil testing verification,the research content can provide reliable logging interpretation and exploration guidance for actual production,and has important significance for exploration and development of buried hill reservoirs.