Inertial borehole survey system

A probe for insertion in a borehole for making measurements therein comprising:

• an elongated tubular outer housing forming a closed pressure vessel;
• means forming a thermal barrier between the exterior of said housing and a chamber within the interior of said housing;
• instrument means disposed in said chamber, said instrument means including electrical circuit means including a member for supporting circuit elements of said circuit means;
• isothermal heat absorbing means disposed in said chamber and in heat flow communication with said circuit means, said heat absorbing means comprising at least one container including a quantity of material operable to change from a first phase to a second phase at a predetermined temperature to maintain a predetermined operating temperature condition of said probe;
• said predetermined temperature being substantially above most ambient temperatures wherein an ambient temperature fluid may be utilized to cool said material.

A probe for insertion into a borehole for making measurements in said borehole, said probe including:

• an elongated cylindrical housing comprising a pressure vessel having opposed head members, at least one of said head members being detachable from said housing to provide access to the interior of said housing;
• an elongated thermal insulating member insertable in said housing and providing a thermally insulated chamber,
• electrical instrument means disposed in said insulated chamber;
• means for maintaining said instrument means in a preselected operating temperature range, said means comprising a plurality of spaced apart containers disposed in said chamber, each of said containers including a quantity of material operable to absorb latent heat in changing from a first phase to a second phase to maintain said operating temperature range of said instrument means;
• a cooling fluid inlet passage in said housing, and means forming a cooling fluid outlet passage in said housing to provide for circulating cooling fluid through said chamber to cause said material to change from said second phase to said first phase to condition said probe for operation of said instrument means.

A method for preparing a probe for insertion in a borehole to make measurements in said borehole, said probe comprising a housing forming a closed pressure vessel, instrument means disposed in said housing, said instrument means being adapted to operate in a predetermined temperature range, isothermal heat absorbing means disposed in said housing including container means containing a quantity of material operable to undergo a phase change from a first phase to a second phase at a temperature which will maintain said instrument means in said operating temperature range, said probe further including means for cooling said heat absorbing means to change said material from said second phase to said first phase, said method comprising:

• circulating cooling fluid in heat exchange relationship with said material at a temperature of said cooling fluid which will change said material from said second phase to said first phase;
• measuring the temperature in said probe to determine if said material has changed to said first phase;
• and
• increasing the temperature of said cooling fluid to cause the temperature of said heat absorbing means to increase to the phase change temperature to stabilize the temperature of said instrument means in said operating temperature range preparatory to making measurements with said instrument means.

A probe for insertion in a borehole for making measurements therein, said probe comprising:

• an elongated cylindrical housing forming a closed pressure vessel and a removable head member of said housing for gaining access to the interior thereof;
• means in said housing forming an inner cylindrical wall defining an interior chamber;
• an elongated instrument assembly adapted to be removably insertable in said chamber, said instrument assembly including a first electrical circuit module adapted to be supported in said chamber, a second electrical circuit module spaced from said first module and adapted to be supported in said chamber, and a rotatable instrument housing interposed between said modules and supported by spaced apart bearing means;
• and
• said bearing means comprising respective electrical slip ring assemblies including stator members supported in said chamber by respective support means releasably engageable with said wall, said slip ring assemblies including respective rotor members connected in supportive relationship to opposite ends of said instrument housing, said instrument assembly including electrical conductor means extending between said slip ring assemblies and said modules, respectively, and electrical conductor means extending between said instrument housing and said slip ring assemblies, respectively.