Research On Key Technologies Of Data Processing For Wellbore Imaging While Drilling

With the urgent need of the development of drilling technology information and intelligence,the imaging technology of wellbore while drilling has become one of the research hotspots in the field of oil and gas well engineering technology.In this paper could be real-time and accurate drilling shaft of the purpose of the measurement data and fidelity of the image display,through the continuous measurement while drilling of well depth,caliper,hole deviation and azimuth and geological parameters,such as data accurately describe the wellbore in time domain in the process of formation change,build a three-dimensional grid,the mathematical model of wellbore,Set up along the wall circumference distribution and vertical distribution of shaft axis measurement while drilling imaging sensor and the mathematical model of wellbore size relations,the formation of borehole imaging based on the MWD information model and spatial three-dimensional imaging borehole wall structure,so as to realize with drilling process real-time 3d digital wellbore show,for real-time geosteering drilling technology to provide theoretical and technical support.Firstly,the principle of attitude measurement of drilling tools and the errors of attitude and trajectory measurement based on magnetic field measurement and gyro measurement are systematically analyzed.Proposed to obtain high density,high precision of shaft center trajectory data and the use of fiber optic gyro measurement technology for drilling trajectory measuring method,completed the development of the optical fiber gyro measurement while drilling prototype,and through the fast search for fiber optic gyroscope north,triaxial acceleration and three-axis fiber optic gyro data fusion,under the condition of dynamic error elimination,A complete set of attitude measurement and data processing methods for gyroscope while drilling is formed.At the same time,the causes of errors in the existing drilling depth tracking system are discussed,and a set of processing methods of depth correction compensation and system accumulation error compensation are established.Through the data processing of FOG trajectory data acquisition,encryption acquisition while drilling depth,encryption calculation of trajectory data and other relevant data processing,the central trajectory data information such as depth,inclination and azimuth required for borehole imaging can be accurately obtained.Through the study of the multi-sensor layout measurement scheme,the measurement method of eccentricity state while drilling using two groups of diameter sensors coupled with fiber optic gyro continuous attitude measurement is established,which is used to solve the quantitative measurement problem of eccentricity of imaging instrument sub in wellbore under the complex motion state of real-time change.A mathematical model is established to calculate the real-time operating attitude of the imaging sensor while drilling in the wellbore using the above measurement methods.Respectively on the measuring instrument while drilling imaging centered within the wellbore,eccentricity,inclination,buckling,rotates coupling and other complicated downhole condition to carry on the simulation,find out the different status under each measurement point on the pillars and wall spacing as time change rule,proved that the measuring instrument while drilling imaging distance and borehole wall is affected by the complicated downhole attitude and orbit of the drill string,The multi-sensor layout adopted can accurately measure and identify the operating attitude of the measurement sensor while drilling,and quantitatively give the real distance between the imaging sensor and the borehole wall required for environmental correction,thus solving the problems of irregular borehole geometry size and eccentricity of measuring points in the measurement of the borehole while drilling.Then the systematic error of the acceleration tool surface in dynamic measurement is corrected by using the inertial navigation technology of gyroscope while drilling,and the study of high frequency continuous imaging sensor measurement tool surface based on fiber optic gyroscope is carried out.Based on the data acquisition and processing mode in time domain,the measurement data of multiple sensors distributed along the axial and annular drillstring where the imaging instrument is located are divided into sectors,so as to obtain the real digital wellbore grid data set of sensor measurement points.According to the analysis of the characteristics of gamma imaging through the formation,the measurement environment correction method under the condition of near bit eccentricity is studied,and the multi-sector anisotropic correction map of drilling fluid attenuation and potassium-based drilling fluid interference of near bit gamma imaging is formed.The method of environmental correction for gamma imaging under eccentric condition is verified by experiments of imaging while drilling simulation device and simulated wellbore.On the basis of the previous research,this paper proposes a real-time construction method of continuous spatial spiral profile along the surface of drilling wall,aiming at the multi-source data of high density depth,inclination,azimuth,diameter and gamma ray while drilling acquired by imaging while drilling,based on the 3D surface modeling theory of parallel contour.The construction rules of continuous helix along the borehole wall were established,the grid homogenization was carried out for the non-uniform multi-source data,and the construction of the borehole wall space quadrilateral was promoted to the three-dimensional space hexahedron,which described the thickness of the borehole.An iterative interpolation method for the spiral contour data of cylindrical surface with inverse distance weighted sliding window was proposed.By processing the experimental data and analyzing the errors,the fidelity of the method for the continuous spiral contour was verified.Through the shaft surface reconstruction method,can use real-time data of the shaft surface to construct the real-time update and fix,construct uniform shaft digital grid around the shaft well,the casing discrete into digital unit grid,eventually form based on continuous contour of the surface of the shaft with drilling space quadrilateral grid and the original data format,The key technology of real-time processing of imaging data while drilling is formed.Finally,the storage format of imaging data is planned and designed.Based on the principle of high cohesion and low coupling,the software conversion module from discrete raw data to imaging data is designed.The processing of imaging data while drilling and the compilation of imaging measurement software system while drilling are completed.By using the real-time data obtained in the field,combined with the simulation test device of imaging while drilling and the simulation test data set of drilling trajectory data,well diameter data and geological survey data formed by the simulation wellbore while drilling,the imaging data processing method of borehole while drilling was used to process the imaging data of borehole while drilling.The 3D surface reconstruction of wellbore and the digital real-time display of additional geological attributes were carried out,which verified the feasibility of the key technology of imaging data processing of wellbore while drilling,thus providing a method and technical support for the imaging technology of wellbore while drilling.