Study On Prediction Method Of High Slope Width Logging Of Reservoir Fracture Based On Rock Fractal Characteristics

With the deepening of exploration and development in Changqing Oilfield in Jiyuan area, most of the wells need effective fracturing before forming capacity, the urgent need to accurately predict fracture height-width by logging data before the pressure for the guidance fracturing operations timely.The paper in order for the study of Yanchang formation in Jiyuan area, as rock brittleness for the main clue, there are mainly about the following five points:①Rock brittleness and shear anisotropy experiments;②Three wave slowness extraction, rock mechanics parameters and rock brittleness coefficient calculation method;③The calculation of rock brittleness coefficient, crustal stress and fracture pressure, the establishment of a cross-sectional;④Based on the rock brittleness coefficient to carry out logging prediction model research on fracture height-width, the analysis of fracturing effect evaluation and influencing factors;⑤Being programmed that based on Forward.net logging interpretation platform and application. There are following five important achievements and understanding:(1) It can be found from the experimental results that rock brittleness coefficient is affected by the rock coring direction(vertical and horizontal), lithology and confining pressure and other factors; Its value will vary significantly increases if the Poisson’s ratio decreases or the Young’s modulus increases; With the fracture width increasing, the fast and slow shear slowness ratio (amplitude ratio) value is larger, the formation anisotropic is more obvious;(2) Based on STC method, DTC, DTS and DTST were extracted from full wave sonic logging data, the establishment of a rock mechanics parameters model, according to the value range of sand-mudstone Young’s modulus and Poisson’s ratio, after comparing to rock brittleness test results, established rock brittleness coefficient logging calculation method which based on Young’s modulus and Poisson’s ratio of the two mechanical parameters;(3) Optimizated and improved horizontal stress and fracture pressure calculation model, Established formation brittle coefficient, stress and fracture pressure profile in Jiyuan area;(4) Established relationship with rock brittleness coefficient between the minimum horizontal principal stress through theoretical derivation, and then seted up a quantitative prediction formula of fracture height based on rock brittleness coefficient when used the modified Iverson model. Meanwhile, obtained the pressure fracture width prediction equation through a combination of rock brittleness coefficients and fracturing parameters and rock mechanics parameters. Evaluated the effect of fracturing using rock brittleness coefficient and shear anisotropy in pre-and post-fracturing, analyzed the affecting the fracturing effect factors from geological and engineering aspects;(5) Programed the fracture height-width prediction program that based on rock brittleness coefficient with Fortran and VB programming optimized language on Forward logging interpretation platform, the models were applied to deal with some wells and achieved good results after fractured detection.Through the above researches on a series of methods, models and data processing, etc, formed a matching methods and techniques about the calculation of rock brittleness coefficient and fracture height-width forecastion and fracturing effect evaluation for Jiyuan area reservoir characteristics. fromed the handling of multiple wells data in work area, models formula and parameters to select is correct, the result is reasonable, that finds an effective way for the use of logging data to predict fracture height-width before reservoir fracturing stimulation.