| The implementation of the temporary plugging section process needs to clear the size of the temporary plugging crack in order to carry out the targeted process design,while the natural fractures of the carbonate reservoir in target oilfield are developed and varied.In order to improve the technology pertinence and effectiveness.It is necessary to predict the static seam width of the natural cracks before pressure and to carry out the acid pressure construction.Then study on the influence of natural crack and artificial crack size.At present,there are four main types of identification and prediction of reservoir fractures,such as direct observation,indirect prediction,logging and seismic interpretation.There are obvious defects in any one method alone.For example,the direct observation method is difficult to reflect the effect of the ground stress field on the crack,and the indirect prediction method is limited by the theoretical model.The cost of logging is high and has multiple solutions.Therefore,based on previous studies,we predicted the width of natural fractures by using tectonic stress field prediction method and logging method,and completed the following work:1.According to the geological structure map,Young's modulus,Poisson's ratio,maximum and minimum principal stress gradient and the direction of in-situ stress determined by logging data,the ground stress field of the O2yjyj layer of the block of the TPT area is retrieved,and the error is within the allowable range.2.Based on the constitutive model of Coulomb Moore?Mohr—Coulumb?criterion and Griffith rupture criterion,the theoretical model between natural crack width,crack density and paleo tectonic stress field is established,and the method of predicting natural fracture width according to the stress strain and line density of rock is summed up,The natural crack width of 5 wells such as TP32 and so on is obtained.The width of the crack is between the 10-5-10-3cm orders of magnitude.3.According to the compensated neutron porosity the porosity of the micro resistance logging and the existing slit width values,the fitting formula of the permeability seam width of the block of the TPT is obtained.The experience is a=0.8072,b=2.4142 and the width of the crack is predicted and the width of the natural crack is also between the 10-5-10-3cm orders of magnitude.4.The calculation width of ground stress field is suitable for strata with structural fractures.From the structure map of the TPT block and O2yjyj position,the structural fractures of this layer are obviously consistent,and the inversion results of the ground stress field are good,making the prediction method more accurate.The porosity prediction method,which relies on the empirical formula,requires higher consistency of the block lithologic parameters,the target horizon is carbonate rock,and the lithologic type is complex and not easy to quantify.Therefore,the poor correlation of regression equation is the main reason for low prediction accuracy.5.To adjust the calculation model of the natural crack width in the present stress field,the width of natural fractures after fracturing in 5 wells,such as TP38,is obtained.The value is between 33-237?m,which is about 12-18 times of the width of the current stress field.6.The reaction characteristics of acid rock in target oil field are mainly influenced by lithology and temperature,the reaction rate between acid and rock is at 10-4mol/cm2·S,the mass transfer coefficient of hydrogen ion is DH+at 10-4cm/s,the reaction speed is more affected by the temperature,and the activation energy Ea is 2-3×104J/mol.7.Filtration test shows that the permeability of the acid corrosion crack can reach more than 300?m2,and the dynamic fracture width of the crack can reach more than 3mm,and the acid corrosion crack groove is even more than 1cm,and the holes in the core are produced in some weak parts,and the depth can reach more than 2cm.8.The acid pressure fitting analysis is carried out by establishing the working process,the acid pressure geological model,the acid pressure fluid model,the actual pump injection program,the acid rock reaction model and so on,which fit the acid pressure fitting analysis of target oilfield.The geometric shape of acid fracturing and its characteristic parameters after fluid reaction were obtained.The width of acid fracturing fissures is 0.12-12.8mm,and the average width is 3.06mm. |
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