Abstract: A system for retractable equipment including movable protection flaps in which a flap drive device serves to drive the flaps in optimized movement, providing a mechanical coupling between the flaps and the retractable equipment such that a common motor member can be used for driving both the equipment and the flaps between respective retracted and deployed positions. The flap drive device includes a cam in the form of a sliding channel secured to a frame of the system and a cam follower in the form of a translating pivot mechanically coupled to both the retractable equipment and a flap drive member. The path followed by the retractable equipment is accordingly optimized.

Abstract: A system for retractable equipment is proposed that has movable protection flaps and in which a flap drive device serves to drive the flaps in optimized movement, while providing mechanical coupling between the flaps and the retractable equipment in such a manner that a common motor member can be used for driving both the equipment and the flaps. The drive device includes a cam secured to a frame of the system and a cam follower mechanically coupled to the retractable equipment and to a flap drive member. The path followed by the retractable equipment can thus also be optimized.

Abstract: Porous, subterranean oil bearing formations penetrated by at least one wellbore are temporarily and reversibly plugged/sealed, by injecting therein a solution of an alkali metal silicate and a gelling agent therefor, permitting said alkali metal silicate and said gelling agent to harden into a relatively impermeable gel, maintaining said gel for period of plugging/sealing time desired, and thence disintegrating said relatively impermeable gel to substantially restore the initial porosity of said formation.