Cable connection to sensors in a well

A cable for connection to sensors permanently or semi-permanently downhole, the cable comprising:

• one or more elongate conductors capable of operative connection to sensors;
• a sheath surrounding the elongate conductors and holding the conductors so as to extend substantially parallel to an elongate axis, wherein the sheath has a cross-section, perpendicular to the direction of the elongate axis, which has a major dimension and a minor dimension;
• and
• at least one strengthening element, spaced from the conductors, where the at least one strengthening element is dimensioned so as to allow passage of a fibre optic cable within it.

A method of cementing a borehole having a wall comprising the steps of:

• placing a conduit within the borehole to form an annulus between the conduit and the borehole wall;
• placing within the annulus a cable with a cross-section which has a major and a minor dimension, such that the minor dimension extends along a radius of the borehole, the cable including at least sixteen elongate conductors;
• and
• passing cement, or thixotropic fluid, into the annulus such that the cable is secured in the annulus and the well is successfully isolated.

A well comprising:

• a borehole being defined by a borehole wall;
• a conduit placed within the borehole so as to form an annulus extending along the length of the borehole between the conduit and the borehole wall,
• a cable placed within the annulus, the cable having a cross-section, perpendicular to the length of the borehole, which has a major and a minor dimension, the cable including at least sixteen elongate conductors;
• and
• cement or thixotropic fluid placed within the annulus successfully isolating the well.

A cable placed in a hydrocarbon borehole between a conduit and a borehole wall, the cable used for connection to sensors permanently or semi-permanently downhole, the cable comprising:

• one or more elongate conductors;
• one or more electrodes adapted for downhole resistivity measurements, each electrode operatively connected to one or more of the elongate conductors;
• and
• a sheath surrounding the elongate conductors and holding the conductors so as to extend substantially parallel to an elongate axis, wherein the sheath has a cross-section, perpendicular to the direction of the elongate axis, which has a major dimension and a minor dimension such that when the cable is placed in the borehole between the conduit and borehole wall the likelihood of successful cementing between the conduit and borehole wall is improved over the same if the cable were not so dimensioned.

A cable placed in a hydrocarbon borehole between a conduit and a borehole wall, the cable used for connection to sensors permanently or semi-permanently downhole, the cable comprising:

• at least one optical fiber;
• at least one tube that is dimensioned so as to allow passage of the at least one optical fiber within it;
• and
• a sheath surrounding the at least one tube so as to extend substantially parallel to an axis of the tube, wherein the sheath has a cross-section, perpendicular to the direction of the axis of the tube, which has a major dimension and a minor dimension such that when the cable is placed in the borehole between the conduit and borehole wall the likelihood of successful cementing between the conduit and borehole wall is improved over the same if the cable were not so dimensioned.