Articulated downhole surveying instrument assembly

A flexible downhole measuring instrument assembly for measuring parameters of a wellbore comprising:

• (a) power source components enclosed in a first cylindrical housing slidably receivable within a drill string;
• (b) measuring device components enclosed in a second cylindrical housing slidably receivable within a drill string;
• and
• (c) a laterally flexible generally cylindrical connector between the first housing and second housing, the connector forming an electrical coupling between the measuring device and the power source, at least a portion of the connector being smaller in diameter than at least one of the first housing or the second housing.

A flexible downhole instrument assembly sized for reception within a short radius directional drill string assembly, comprising:

• instrument components for conducting measurements of downhole parameters;
• a plurality of housings disposed in mutual longitudinal proximity for enclosing said instrument components, said housings arranged for sliding movement within the drill string assembly;
• and
• flexible connector means extending longitudinally between and connected to said housings, said flexible connector means having an intermediate portion which is substantially smaller in transverse cross section than said housings.

A downhole instrument assembly for conducting measurements of downhole parameters, said instrument assembly being arranged for insertion within a short radius directional drilling bottom hole assembly in a drill string, including a drill bit, such measurements being sensitive to magnetic materials in the downhole environment, comprising:

• cable connector means at the upper end of the instrument assembly for attaching a cable to lower the instrument assembly into the drill string and to retrieve the instrument assembly from the drill string, said connector means being sized for sliding reception within the drill string;
• instrument housing means located in the instrument assembly for enclosing instrument components, said housing means being sized for sliding reception within the drill string above the drill bit;
• seating means at the lower end of the instrument assembly for seating the instrument assembly within the drill string above the drill bit;
• and
• spacer bar means located in the instrument assembly between said cable connector means and said seating mans for positioning said instrument housing means at a predetermined desired location within the drill string above the drill bit, said spacer bar means being constructed of a non magnetic metal which is rigid in axial tension and compression and having upset end portions which are of substantially the same outer diameter as said cable connector means and as said housing means, said upset end portions being joined by a flexible intermediate section which has a substantially smaller outside diameter than said upset end portions for providing sufficient flexibility to the assembly to permit its use within a drill string for drilling short radius directional boreholes.

A flexible downhole measuring instrument assembly for use within a wellbore, comprising:

• (a) a plurality of instrument components, said components divided into at least two groups;
• (b) a plurality of longitudinally separated housings, each enclosing at least one instrument component group;
• (c) a laterally flexible coupling extending between and interconnecting said housings;
• and
• (d) at least one spacer bar associated with and longitudinally connected to the instrument assembly, said spacer bar including interconnectable end sections and a laterally flexible intermediate section extending longitudinally therebetween.