Abstract: A method of forming a wellbore is provided that in one embodiment includes conveying an inner string and an outer string downhole; attaching the inner string to the outer string at a first location and forming the wellbore; and attaching the inner string to the outer string at a second location uphole of the first location and cementing an annulus between the outer string and the wellbore, without retrieving the inner string from the wellbore.

Abstract: In one aspect, the disclosure provides a method of drilling a wellbore, which method, in one embodiment, includes the features of drilling the wellbore with a drill string that includes a bypass device having a fluid passage therethrough by supplying a fluid through the bypass device, wherein the drilling fluid circulates to the surface via an annulus between the drill string and the wellbore; defining a time period (locking time); initiating a selected drilling parameter; detecting downhole the selected drilling parameter and one of the second flow rate and a differential pressure; and activating the bypass device when the selected drilling parameter and one of the second flow rate and the differential pressure are present during the defined time period to divert a portion of the drilling fluid from the bypass device to the annuls. In one aspect, the selected drilling parameter is rotation of a member associated with the bypass device.

Abstract: A core drill assembly with replaceable fluid nozzles permitting effective total flow area adjustment (TFA), substantial optimization of hydraulic force at the cutting face to improve rate of penetration (ROP) and core quality. At least one seal assembly to restrict drilling fluid flow while permitting mutual rotation between the core head ID and the lower shoe is disposed in an annulus defined therebetween.

Abstract: The present invention provides methods of forming mud motors. In one method, rollers are urgingly stroked against a tubular member having a mandrel therein that has an outer profile which is the inverse of the desired profile of the stator. In another method, rollers are urged and rotated radially on the tubular member with the mandrel disposed in the tubular member. In yet another method, dies are pressed against the tubular member having a mandrel with a desired outer profile. In another method, a molten metal is deposited over a mandrel with an outer lobed surface that is substantially the inverse of the desired inner profile of the stator housing. The mandrel is then removed, leaving a metallic longitudinal member having an inner profile defined by the outer profile of the mandrel. In each of these methods, the inner surface of the resulting member has the profile defined by the outer profile of the mandrel.