A steering head for use with a casing, the steering head having a body with a first body end with a lead edge, a second body end with a rear edge, and a body surface extending from the lead edge to the rear edge, an outer tube with an internal side generally facing the body surface, the outer tube extending from the first body end to the second body end, and a steering flap disposed on an external side of the outer tube having a first flap face facing radially inwardly and a second flap face facing radially outwardly. A fluid dispenser is disposed in a void defined between the outer tube and the body.

A method of electrically logging a section of a wellbore includes circulating an oil-based wellbore fluid within the wellbore and allowing filtration of the oil-based wellbore fluid to form a conductive filtercake on a wall of the wellbore; placing within the wellbore a wellbore logging tool with at least one pad capable of applying a current to a portion of the conductive filtercake and wellbore wall; applying electrical current from the at least one pad; and collecting an electrical log of the portion of the wellbore that has had electrical current applied thereto.

A method of electrically logging a section of a wellbore includes circulating an oil-based wellbore fluid within the wellbore and allowing filtration of the oil-based wellbore fluid to form a conductive filtercake on a wall of the wellbore; placing within the wellbore a wellbore logging tool with at least one pad capable of applying a current to a portion of the conductive filtercake and wellbore wall; applying electrical current from the at least one pad; and collecting an electrical log of the portion of the wellbore that has had electrical current applied thereto.

A method for evaluating a formation fluid includes the steps of drilling a borehole intersecting a formation with a drill string, circulating a drilling fluid in the wellbore, selectively liberating a formation fluid from the formation, injecting the liberated fluid into the drilling fluid returning to the surface, drawing a sample of the returning drilling fluid at the surface, and estimating at least one parameter of the drawn sample at the surface.

A method for evaluating a formation fluid includes the steps of drilling a borehole intersecting a formation with a drill string, circulating a drilling fluid in the wellbore, selectively liberating a formation fluid from the formation, injecting the liberated fluid into the drilling fluid returning to the surface, drawing a sample of the returning drilling fluid at the surface, and estimating at least one parameter of the drawn sample at the surface.

A method of estimating properties of wellbore cement by penetrating the cement, and monitoring the amount of energy or power required for penetrating the cement. Penetrators include a drill bit that bores into the cement, and probes or pins that are forced into the cement. The energy or power monitored can be current and/or voltage supplied to a motor that drives the drill bit or probe. Comparing the monitored energy or power with that required to penetrate a reference cement sample of known properties can yield information about the cement being sampled. When the wellbore is lined with multiple coaxially disposed strings of casing with cement between adjacent strings and on the outer surface of the outer string; the method further includes obtaining core samples from portions of each string, each layer of cement, and formation adjacent the wellbore.

A method for estimating equivalent top of fluid level or a theoretical surface annular back pressure in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to compute the equivalent top of fluid level and/or theoretical surface annular back pressure of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of values corresponding to various wellbore intervals. The equivalent top of fluid level and/or theoretical surface annular back pressures may be used in automated managed pressure drilling operations.

A method for estimating equivalent top of fluid level or a theoretical surface annular back pressure in a subterranean wellbore includes acquiring first and second axially spaced pressure measurements in the wellbore. The pressure measurements may then be processed to compute the equivalent top of fluid level and/or theoretical surface annular back pressure of drilling fluid between the measurement locations. A tool string including a large number of axially spaced pressure sensors (e.g., four or more or even six or more) electronically coupled with a surface processor via wired drill pipe may be used to obtain a plurality of values corresponding to various wellbore intervals. The equivalent top of fluid level and/or theoretical surface annular back pressures may be used in automated managed pressure drilling operations.

Methods for designing lost circulation materials for use in drilling wellbores penetrating subterranean formations may involve inputting a plurality of first inputs into a numerical method, the plurality of first inputs comprising a lost circulation material property input of a first LCM; calculating a plurality of first outputs from the numerical method; inputting a plurality of second inputs into the numerical method, the plurality of second inputs comprising the lost circulation material property input of a second lost circulation material; calculating a plurality of second outputs from the numerical method; comparing the first outputs to the second outputs; and developing a drilling fluid comprising a third lost circulation material based on the comparison of outputs.

Methods for designing lost circulation materials for use in drilling wellbores penetrating subterranean formations may involve inputting a plurality of first inputs into a numerical method, the plurality of first inputs comprising a lost circulation material property input of a first LCM; calculating a plurality of first outputs from the numerical method; inputting a plurality of second inputs into the numerical method, the plurality of second inputs comprising the lost circulation material property input of a second lost circulation material; calculating a plurality of second outputs from the numerical method; comparing the first outputs to the second outputs; and developing a drilling fluid comprising a third lost circulation material based on the comparison of outputs.