Research On Prediction Of Reservoir Interface In Horizontal Well

With development of petroleum industry, the exploration targets are transited from simple structure to the complex. The logging while drilling not only has played an important role in evaluating reservoir, such as the highly deviated well, the horizontal well and multilateral well of slim hole sidetracking, but also has represented importance in drilling design of highly deviated well and horizontal well. Besides, it becomes a key technology to data acquisition in field and interpretation, locale decision-making and geometry steerable drilling. The prediction of reservoir interface during drilling is an important task urgently to be solved in logging while drilling and geo-steering and has significant function and meaning for drilling guidance in real time to achieve geo-steering and improving the drilling meeting efficiency.This paper mainly researches the reservoir interface based on electromagnetic wave while drilling. Starting from the theory of electromagnetic propagation in layered medium, the reflection and transmission in formation interface of TE wave and TM wave emitted by transmitter are respectively studied to obtain the strict analytical solutions which meet all boundary conditions of formation interface in any inclined layered medium and further to achieve the forward of electromagnetic wave while logging. The comparision and analysis of forward results and resistivity correction map of sperry-sun EWR4 shows that it is feasible to use analytical method of electromagnetic propagation to determine the formation interface. Bases on this, the inversions using marquardt method, such as single parameter inversion (thickness of target layer), double parameter inversion (thickness of target layer, distance from interface) and three parameter inversion (thickness of target layer, distance from interface, resistivity of lower shoulder bed) , are respectively studied and analyzed. The inversion result of practical data shows that the marquardt inversion method has good effect. A set of forward and inversion methods and software are finally formed to achieve the determination of distance from interface during drilling based on electromagnetic wave while drilling. Besides, this paper does some basis research of natural gamma-ray logging while drilling and lays a good foundation for further determination of distance by natural gamma-ray logging.