Formation Anisotropy Analysis And Evaluation Of Fracturing Effect

Today, the most widely used and effective techniques of the oil field production and unconventional oil and gas field developmentfor is hydraulic fracturing in the world, the major logging methods to evaluation of fracturing effect including the temperature measuring method,isotope method and boron injection neutron lifetime logging detection method, but the existing method to evaluate reservoir fracturing results generally are poor reliability and practicability.the application of Sound waves in anisotropic casing has been proved to be a kind of evaluation of fracturing effect and the effective method to determine fracturing fracture characteristics, This method is intuitive and accurate, and can be applied to low porosity low permeability reservoir fracturing effect evaluation. Commonly used method to compute the anisotropic including azimuth rotation method and waveform inversion method are based on the objective function. Domestic scholars mainly think waveform inversion formula as the objective function and improve it in speed and accuracy. In the process of actual data processing, bearing rotation method in speed of shear wave slowness is less than the difference between the slowness estimation method of system error, the anisotropic azimuth change often, anisotropy index accuracy is not high; Waveform inversion method based on the objective function is due to its global two-dimensional simulated annealing inversion, the amount of calculation is too large, does not apply to actual data processing. And new waveform inversion method is put forward in this paper through waveform matching inversion method to compare the difference between the fast shear wave and slow shear wave slowness, the 2 d inversion into two one dimensional inversion, so as to reduce the amount of calculation, and in one dimensional inversion speed at the same time improve the accuracy of the anisotropic azimuth and index.Paper based on the theory of acoustic wave propagation simulations of elastic wave propagation in the well and dipole acoustic waveform characteristics are analyzed theoretically and provide guidance for the subsequent data processing. On this basis, the dipole acoustic signal processing method in the time difference between extraction and anisotropy inversion method. Based on the differences of formation anisotropy degree before and after fracturing, the dipole acoustic data is proposed to assess the formation fracturing effect method, and compiled the corresponding software, through the analysis of actual data processing results as follows:(1) On XMAC original measurement data preprocessing (including to gain, filtering, equalization), in the time domain and frequency domain respectively, the time-slowness correlation method and the method of phase, the actual data processing results compared with the EXPRESS software processing results, the overall error is small, fast easy to explain personnel operation.(2) According to different application requirements and logging data, choose a different method, put forward the anisotropy inversion based on waveform matching size and orientation of the objective function method, the uncertainty of the effective ways to overcome the Alford rotating bearing and two-dimensional global simulated annealing inversion computation problem. And implements dual extremely fast and slow shear wave acoustic data and the extraction of anisotropic Angle.(3) According to the degree of anisotropy value before and after fracturing and the pressure difference to determine fracture height, so as to evaluate formation fracturing effect. If fracturing before and after fracturing anisotropic changed little, formation fracturing effect is poor; If after fracturing of anisotropy is more than in the anisotropic before fracturing, reservoir fracturing effect is good, and anisotropy, the greater the difference before and after fracturing effect is better.