Feasibility Research Of Optical Communication While Drilling

Signal transmission is the key link with the MWD.In the recent situation,the LWD transmission technology mainly focused on pulse transmission in the mud,electromagnetic wave transmission,acoustic transmission,cable transmission,etc.However,the ways of transmission have short comings such as limited communication capacity,high construction cost,short communication distance and drilling efficiency interference.In contrast,fiber optic transmission technology with drilling has huge advantages such as long transmission distance,large bandwidth,strong anti-interference ability and low cost.Therefore,it has important significance of research.The paper mainly carries out theoretical analysis,simulation and experiments on the bending loss and mechanical characteristics of optical fiber while drilling,as well as researches and designs on the working process and key components of fiber optic communication while drilling.The main research contents and achievements are as follows:(1)According to the actual working conditions the fiber Macrobending loss fluctuation theory and fiber logging while drilling process.Through finite element modeling and simulation research analyzed by the Comsol software on the fiber Macrobending loss,We obtain the influence factors of the standard single-mode fiber Macrobending loss by fiber bending radius and bending length,working temperature and communication wavelength.(2)According to the calculation results of macro bending loss,we designed and carried out the optical fiber macro bending loss test experiment,and got the energy loss data under different working wavelength,bending length and temperature.According to the theoretical and experimental results,it verified the feasibility of optical fiber communication while drilling,and provided theoretical guidance for the storage condition and wavelength selection of optical fiber inside drill pipe.(3)Through the analysis of the force on the inside of the drill pipe logging fiber,a mathematical model for drilling fiber optic maximum tension,maximum axial strain.Calculated and analyzed through the well data and the Ansys finite element model of the mechanical properties of fiber in the underground conditions.At the same time,the maximum tension of the single mode fiber is tested.Through the mutual verification of the theoretical calculation and experimental data,the feasibility of the optical fiber communication in the drilled is determined.(4)According to the actual working condition of LWD,a communication winch component which can store optical fiber and built-in wireless transceiver module is designed.and a set of fiber optic communication system while drilling is put forward,the operation process is also presented.Through the communication winch and working process,we can achieve high efficiency optical fiber communication while drilling without affecting normal drilling constructior.At the same time,we greatly enhance the distance of fiber optic communication while drilling,enhance the communication bandwidth and reduce communication costs.