Abstract: A production pipe for production of oil or gas from a well in an oil and/or gas reservoir, or for injection of fluids into a well in an oil and/or gas reservoir, includes a production pipe with a lower drainage pipe. The drainage pipe is divided into sections with one or more inflow restriction devices which control the flow of oil or gas from the reservoir into the drainage pipe on the basis of calculated loss of friction pressure along the drainage pipe, the calculated productivity profile of the reservoir, and the calculated inflow of gas or water.

Abstract: Hydraulic high density cement slurry, especially for cementation of oil/gas-wells. The slurry contains 30-45 weight % microsilica based on the cement weight and water to a density of 1.9-3.5 g/cm.sup.3. If desired there can be added dispersant, retarder and weighting agent. Microsilica acts as a fluid-loss preventing agent. The addition of microsilica prevents strength retrogression at temperatures above 120.degree. C. and acts as a mechanical stabilizer for the cement slurries. A method for production of the cement slurry is also described.