Research On Recognition Method Of Fracturing In Horizontal Wells Based On Acoustic Logging

The Triassic in Longdong area Erdos basin Yanchang formation is a typical low porosity and low permeability tight reservoir,only the industrial capacity by fracturing before.At present,logging detection technology of vertical well fracturing has been quite mature,but in the identification and evaluation of the fracturing level casing well in terms of the lack of supporting technology and economy mature and practical detection reliable logging,especially in the presence of some technical problems and development of horizontal well fracturing position detection using logging means and length width parameters,it is necessary to further exploration and research.In this paper,acoustic wave signals in the perforated section of horizontal wells are collected by means of acoustic wave variable density and dipole shear wave logging techniques,and the interpretation method is optimized.To identify and evaluate the development degree,orientation and effectiveness of fracture pressure in horizontal wells,the following research results and understandings have been obtained:(1)Based on the principle of similarity,the experimental simulation wells with fractures in sandstone formation of horizontal casing wells are established.The sonic variable density logging and dipole shear wave logging experiments are completed for horizontal wells with transverse orthogonal compression fractures,and sound wave full wave train diagrams are drawn.Waveform variable density diagram and four-component dipole shear wave waveform diagram,and the logging response characteristics of horizontal well fractures are observed successfully,which forms the experimental theoretical basis for identifying and evaluating horizontal well fracturing based on acoustic variable density logging and dipole shear wave logging.(2)To study the theoretical methods and technical principles of acoustic variable density logging,dipole shear wave logging and acoustic remote logging to identify and evaluate fracture pressure in horizontal wells,to analyze the characteristics of fracture response,to extract the relative sonic time difference,and to extract the second interface cementation index.Relative to the amplitude of sound wave,the difference of brittleness index before and after compression and the anisotropy coefficient of shear wave are used to detect and evaluate the fracturing of horizontal wells.(3)Based on the TTI fracture medium model,the relationship between shear wave anisotropy and well angle,well inclination angle,fracture dip angle and fracture azimuth angle is studied.The theoretical derivation and simulation calculation are carried out for three cases:vertical well,horizontal well and inclined well.The variation of velocity and anisotropy coefficient with well inclination,fracture inclination and azimuth are obtained.The results of the model are in agreement with the theoretical analysis.(4)Collate the existing conventional logging data and rock mechanics experimental data in the working area,and carry out the rock mechanics parameters of horizontal wells through gamma log curve,longitudinal and shear wave move out log curve,density logging curve,after correction of vertical depth of inclined well,etc.The fine interpretation of formation three pressure and ground stress,the establishment of rock mechanics parameters,the formation three pressure and ground stress profile,which provide basic data for calculating the fracturing parameters of horizontal well perforation section.(5)In this paper,a prediction model for the geometric parameters of fracture pressure in horizontal wells is established,from which the parameters such as length,width and height of fractures in many horizontal wells in the working area are calculated.At the same time,the MPAL and other logging data after actual horizontal well pressure are detected and processed to identify the pressure fracture with the shear wave anisotropy and sensitive parameters,and the two-dimensional synthesis diagram showing the shape of the pressure fracture along the well trajectory is drawn.The fracture height of each fracturing section,the length of fracturing well and the relationship between fracture height and the crossing of reservoir can be seen directly from it.(6)Based on the Lead3.0 logging interpretation software platform,the vertical depth correction module of inclined well,the calculation module of rock mechanics parameters and three stresses and three pressures in horizontal well,the calculation module of length,width and height parameter of fracture pressure in horizontal well are compiled.A set of comprehensive interpretation software of horizontal well pressure fracture is developed,which is based on the identification,detection and evaluation module of horizontal well pressure fracture,and the synthesis diagram module of horizontal well trajectory and pressure fracture,and a set of comprehensive interpretation software of horizontal well pressure fracture is formed.