Research On The LWD Data Pre-Processing Technology Based On The SDRI-LWD

The data pre-processing of Logging While Drilling (LWD) is important to the LWD interpretation. The aim of this thesis is based on the LWD system made by Shengli oilfield Drilling Research Institute (SDRI-LWD) to research the data pre-processing technology and make the interpretation of the SDRI-LWD more accuracy. According to the structures, functions and features of the SDRI-LWD, the pre-processing contents and procedures of the SDRI-LWD are addressed. Key data pre-processing algorithm of the SDRI-LWD is discussed in detail, and relevant software procedures are designed. According to the basic methods of the well depth measurement and impact factors to the measurement, an adaptive depth correcting method is adopted to make the measurement more accuracy. Telemetry methods of SDRI-LWD are introduced, high-efficiency and reliable coding methods are designed. Based on the basic theory of the true vertical depth (TVD) correcting and the conversion method of measurement depth (MD) to TVD, the MD-TVD conversion procedure is designed. According to the error sources and its features of LWD results, smooth filtering methods and relevant filtering factors of SDRI-LWD are determined. By using the interpolation of the 1D Akima piecewise cubic polynomial function, the logging curves interpolation function is designed, which avoiding the curves burr caused by the change of the rotate of penetration and the low telemetry speed. A standard depth-memory data file is made by the memory data processing procedure based on the system time of the computer. Reasonable procedure of LWD tool scaling and quantities transferring are constructed, which can be traced to the industry standard of the wire logging. Identical quantities between SDRI-LWD and wire logging can be acquired by scaling and calibration of SDRI-LWD. Field test results show that the LWD data pre-processing technology based on the SDRI_LWD can be applied in the LWD interpretation effectively.