Directional drilling with adjustable bent housings

A method of forming and operating an adjustable drill string housing to form a branch wellbore therewith, comprising:

• providing an annular member defining an initial bend angle therein about a bend axis, the bend angle defined between upper and lower longitudinal axes extending through respective upper and lower ends of the annular member;
• pre-stressing at least one support member on the annular member that is radially offset from the upper and lower longitudinal axes and extends across the bend axis to move the annular member to a first configuration wherein the upper and lower longitudinal axes are disposed at a first bend angle different from the initial bend angle;
• running the annular member into a main wellbore on a drill string with the annular member in the first configuration;
• locating a casing window in the main wellbore with a drill bit supported by the annular member in the first configuration;
• triggering, with the drill bit extending through the casing window, a change in an internal stress in the at least one support member to thereby bend the annular member from the first configuration to a second configuration within the wellbore;
• and
• rotating the drill bit with the annular member in the second configuration to form the branch wellbore.

A method of forming a branch wellbore, comprising:

• running a bottom hole assembly into a main wellbore on a drill string;
• adjusting a bend angle, within the main wellbore, of an adjustable drill string housing defined by the bottom hole assembly to thereby induce a contact between the bottom hole assembly and a casing in the main wellbore;
• moving the bottom hole assembly in contact with the casing to a window defined in the casing such that the contact is relieved;
• detecting the relief of the contact;
• and
• commencing drilling the branch wellbore through the window in response to detecting the relief of the contact.