Abstract: The invention relates to a packer for separation of zones behind casing in a well bore. It comprises a casing string serving as mandrel for the packer, an expandable packing element and first and second sleeves tightly fixed to the peripheries of the packing element, wherein the first sleeve is sealed and movable in respect of the casing string and the second sleeve is tightly fixed to the casing string.According to the improvement in this invention, a sleeve plug slides on and is sealed against the casing string and has a thicker upper part and a thinner lower part, the upper part is slidingly arranged at least partially between the casing and the collar and is sealed against both of them, the lower part is slidingly arranged at least partially between the casing and the packing element. The first sleeve slides tightly on the sleeve plug. A non-return valve in the casing connects the inside and the outside of the casing at the packing element.

Abstract: The invention concerns apparatus for performing underground measurements during drilling of underground strata using conventional measuring instruments. It comprises a closed instrument casing filled with oil, an adaptor coupling the casing to the drilling pipe, a spring holder connected to the instrument casing and carrying damping spring means, a helical plate controlling angular displacement and a piston-and-cylinder displacement control device, a first bore in the adaptor for conveying mud to a downward section of the drilling pipe, a second closable bore in the adaptor for permitting mud to flow from the annular space around the pipe through the instrument casing, and a closable bore in the instrument casing for communicating the pressure in the interior of the drilling pipe to the instrument casing.