Rupture-Resistant Filter Cake for Wellbore Strengthening

点击翻译按钮获取中文摘要

Fluid losses usually occur through fractures caused by the drilling pro- cess. To avoid this phenomenon,a series of techniques has been developed to raise the integrity of the wellbore, stopping lost circulationand allow drilling with wellbore pressures in excess of the fracture gradient. These techniques are calledwellbore strengthening. A typical example of wellbore strengthening mechanism consists of addingparticiples to the drilling mud. When a fracture occurs these participles enter in the fractures and obstructit forming a bridge. However, in the last years a new theoretical wellbore strengthening mechanism hasbeen individuated which consists in the formation of a filter cake, which builds up on the wellbore wallsbecause the fluid pressure in the pore space in a permeable formation is lower than the boreholepressure.This research will involve a combination of laboratory experiments and numerical analysis of the efficiencyof the filter cake in prevent fractures in the rock formation and their propagation. A parametric study willbe con- ducted to achieve specific filter cake properties (e.g. permeability, thickness and strength), whichincreases the fracture gradient in the rock formation and consequently minimizes the fluid lossesduring the drilling process.