Conoco Inc.

John L Stalder

William L Martin

An improved prestressed conduit string for conducting heated fluids through a well bore comprised of a plurality of concentric double wall tube conduit sections each including an inner heated fluid conductor tube in tension prestress and a larger diameter outer tube in compression prestress to reduce heat transfer from the conducted fluids and prevent deformation of the conduit string when heated. By the present invention, the outer tubes of the conduit sections are shorter than the conductor tubes thereof whereby the ends of the conductor tubes extend short equal distances beyond the ends of the outer tubes. Connector means for connecting the conduit sections together in end-to-end relationship thereby forming the conduit string are comprised of annular resilient seal means positioned around axially aligned adjacent extending ends of the conductor tubes of adjacent conduit sections and coupling means positioned around the seal means and connected to the outer tubes of adjacent conduit sections thereby rigidly connecting the sections together and compressing the seal means against the sides of the adjacent extending ends of the conductor tubes and forming a sealed heat insulated joint between the conduit sections.

Insulated prestressed conduit string for heated fluids

Methods and apparatus for insulating a well bore to reduce heat transfer between fluids flowing through the well bore and surrounding formations wherein a heat activated gel-forming fluid having heat insulating properties when gelled is introduced into the annular space between the well bore and the tubing string contained therein and caused to be gelled.

Method for thermally insulating wellbores

A method for the insertion of shear degradable aqueous polymer solutions in a polymer thickened flood wherein a series of pumps are used in a multi-branch system, while reducing shear degradation while maintaining pressure and rate control within any branch of said multibranch system comprising utilizing hydraulic drivers for the pumps wherein the hydraulic power source for the drivers is controlled (a) by a pressure sensing loop such that a selected preset pressure will not be exceeded by any branch of the injection system, and (b) by a rate proportioning control loop whereby the injection rate in the various branches of the multi-branch system will be maintained in a given proportion to one another regardless of rate changes in a designated master branch or in the total injection stream. Polymer shear rates are reduced by using plunger pumps, progressive cavity pumps, diaphram pumps or other low shear pumps for the polymer injection while utilizing throttle valves and hydraulic pumps for the hydraulic oil power system. An optional manually controlled variable speed drive can minimize the amount of bypassed hydraulic power oil.

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Ventura, CA, United States of America

John L Stalder