Smith International, Inc.

Other

Schlumberger Technology Corporation

Leon Ceh

Graham A McElhinney

Kenneth Stenerson

Euan Forbes

Methods for improving wellbore survey accuracy and placement are disclosed. The Earth's magnetic field may be measured at a magnetically clean surface location and correlated with a non-magnetic reference direction to obtain a direction of the Earth's field (e.g., a magnetic declination or a magnetic inclination). The direction of the Earth's magnetic field may in turn be processed in combination with magnetic measurements made in a subterranean borehole to obtain one or more survey parameters.

Method for improving wellbore survey accuracy and placement

A bottom hole assembly configured for a subterranean drilling operation having a drill bit; a downhole tool deployed above the drill bit, at least a portion of the downhole tool free to rotate with respect to the drill bit about a longitudinal axis of the bottom hole assembly a sensor sub deployed axially between the drill bit and the downhole tool, the sensor sub configured to rotate with the drill bit about the longitudinal axis of the bottom hole assembly and free to rotate with respect to the downhole tool about the longitudinal axis and a tri-axial magnetic field sensor deployed in the sensor sub.

At-bit magnetic ranging and surveying

A method and apparatus for imparting a transverse magnetization to a wellbore tubular is disclosed. In certain exemplary embodiments, tubulars are magnetized to include at least one flux reversal (e.g., at the center of the tubular) at which the direction of the transverse field changes (i.e., from pointing radially inward to pointing radially outward). A plurality of such magnetized wellbore tubulars may be coupled together and lowered into a target well to form a magnetized section of a casing string. Exemplary embodiments of the invention may be utilized to impart a strong, highly uniform magnetic field about a string of wellbore tubulars, thereby providing for improved passive ranging and wellbore twinning.

Transverse magnetization of casing string tubulars

A stack of magnetized casing tubulars includes a plurality of magnetized wellbore tubulars each of which includes a plurality of north and south magnetic poles imparted to a corresponding plurality of longitudinal positions along the tubulars. The plurality of wellbore tubulars are arranged into a stack having at least two rows and at least two columns, the wellbore tubulars are stacked side by side and atop one another such that the magnetic poles on one tubular are radially aligned with magnetic poles of an opposite polarity on adjacent tubulars. Such a configuration advantageously substantially eliminates weakening of the imparted magnetic field due to interaction of the magnetic poles on adjacent tubulars.

Magnetized casing string tubulars

A method for magnetizing a wellbore tubular includes a positioning a wellbore tubular substantially coaxially in a plurality of longitudinally spaced magnetizing coils deployed on a frame. The coils are selectively connected and disconnected from electrical power such that a circumferential electrical current flows in each of the coils to impart a predetermined magnetic field pattern to the tubular. Exemplary embodiments of this invention provide for semi-automated control of tubular magnetization and thereby enable a repeatable magnetic pattern to be imparted to each of a large number of wellbore tubulars.

Method for magnetizing casing string tubulars

An apparatus for magnetizing a wellbore tubular includes a plurality of co-axial magnetizing coils deployed on a frame. The coils are typically deployed about a track on which the tubular may be traversed. Exemplary embodiments may further include a magnetic field sensor disposed to measure the imparted magnetic field along the length of the tubular as it is removed from the track after magnetization. Exemplary embodiments of this invention provide for semi-automated control of tubular magnetization and thereby enable a repeatable magnetic pattern to be imparted to each of a large number of wellbore tubulars.

Growing community of inventors

Calgary, Canada

Leon Ceh