西南石油大学学报（自然科学版）2024，Vol.46Issue(4)：85-96,12.DOI:10.11885/j.issn.1674-5086.2024.06.06.01
超深、特深碳酸盐岩多场-损伤耦合破裂压力计算
Numerical Calculation of Multi-field Damage Coupling Fracture Initiation Pressure for Ultra-deep and Extra-deep Carbonate Reservoirs
摘要
Abstract
Ultra-deep carbonate reservoirs are characterized with high initiation pressure,leading to difficulties in fractures initiating.Acid can react with the reservoir matrix,enhancing porosity,increasing permeability,and deteriorating the mechanical properties of the rock,thereby reducing the initiation pressure.However,there lacks accurate calculation methods of fracture initiation pressure for acid-damaged carbonate reservoirs,making it challenging to design initiation pressure reduction measures.This study tested the dynamic Young's modulus of cores after drilling fluid immersion and acid displacement,establishing a damage evolution equation for carbonate rocks under different fluid disturbance states.In addition,a numerical calculation model was established to couple flow,chemical,and stress-damage fields during acid fracturing to estimate the fracture initiation pressure.The results indicate that when both drilling fluid and acid fluid are affected,for reservoirs with a porosity below 4.32％and an acidizing time less than 4.08 minutes,the damage factor is below 0,which means that it is unable to mitigate the increase in Young's modulus caused by drilling fluid.During the operation of"acid displacement of wellbore+acid immersion damage+acid fracturing",the 8 833 m section of Well Pl reached the fracture initiation condition at the 73rd minute with the damage factor of 0.301 and fracture initiation pressure decrease of 29 MPa;as a result,this well was opened successfully.The calculation deviation of the model ranged from 1％to 5％,resulting in an improved accuracy of 3 to 10 percentage points when compared to traditional analytical models,this indicates that the model is particularly valuable for the calculation of fracture initiation pressure and designing acid damage measures in the Dengying Formation,as well as in similar carbonate reservoirs.关键词
碳酸盐岩/超深、特深层/酸损伤/破裂压力/降破工艺Key words
carbonate rocks/ultra-deep and extra-deep reservoirs/acid damage/fracture initiation pressure/technology of reducing fracture initiation pressure分类
能源科技引用本文复制引用
郭建春,管晨呈,任冀川,苟波,曾冀..超深、特深碳酸盐岩多场-损伤耦合破裂压力计算[J].西南石油大学学报（自然科学版）,2024,46(4):85-96,12.基金项目
国家自然科学基金(U21A20105,52304047) （U21A20105,52304047）
