Patent ID: 7308952

Claim:
A method of drilling a well bore through and below a subterranean permeable formation bearing at least one of oil, gas, water, said method using a drilling rig, and a drill string having through bore and including interconnected joints of drill pipe, the method comprising: (a) providing a well bore casing at the top of said permeable formation (b) providing a rotating blow out preventer for controllably sealing the annulus between said casing and said drill string; (c) providing means for controllably producing the formation fluid through the drill string; (d) providing means for selectively separating at least drill cuttings from the wellhead stream comprising drill cuttings and at least one fluid; (e) drilling the well bore through said permeable formation, flushing the well bore with a drilling fluid being circulated from the surface until manifestations of the formation reach a predetermined value, said manifestations comprise lost circulation and influx of the formation fluid, (f) establishing a controllable flow of the formation fluid through the drill string at a predetermined rate said rate is at least sufficient for transporting drill cuttings to the surface through the drill string; (g) advancing the well bore while flushing it with the formation fluid being produced, such that formation fluid flows to the drill bit, picks drill cuttings up, and evacuates them through the through bore of the drill string to the surface; (h) operating said means for producing formation fluid, and controlling penetration rate such that formation fluid production rate remains substantially stable at a value at least sufficient for (trill cuttings evacuation; (i) pumping formation fluid, being produced while drilling, into casing/drill string annulus, enclosed with rotating BOP, at a rate ranging from 0 to 100% of the formation fluid production rate.