Patent ID: 9091149
Filing Date: 2015-07-28
Classification: E21B

Abstract:
1. A method of diagnosing a cause of a drilling fluid lost circulation event, the method comprising: recording data regarding: a rate of drilling fluid loss at the time of the event, cumulative drilling fluid losses as a function of drilling depth, borehole material electrical resistivity as a function of drilling depth, a predicted pore pressure at the time of the event, a predicted fracture gradient at the time of the event, leak-off test behavior prior to or at the time of the event, porosity and permeability information of material at an estimated location of the event, a rate of drilling fluid loss at a time after a lost circulation pill treatment, a borehole image, gamma ray emissions of material at an estimated location of the event, a tectonic regime of material at an estimated location of the event, an equivalent circulation density at an estimated location of the event, borehole temperature as a function of drilling depth, drilling fluid salinity, presence of fractures at an estimated location of the event, fault conductivity at an estimated location of the event, drilling fluid gain when drilling fluid is not being pumped, borehole trajectory, and drill bit drag and penetration rate at the time of the event; classifying, based on the data, the event as at least one of: seepage, borehole breathing, induced axial fracture, induced near-orthogonal fracture, natural fracture, vugulars, and ineffective isolation of casing shoe; determining remedial measures, based on the classifying, to at least partially cure the event; and implementing the remedial measures.