Atlantic Richfield Company

Gary D Herring

James K Eastlack

James D Ashford

Curtis G Blount

William N Wilson

David R Underdown

Terry W Harrison

A squeeze silicate operation carried out through a coiled tubing for sealing upper perforations in a well casing to prevent flow of excess gas. A sodium silicate mixture is used which has a diverter material therein which rapidly builds a filter cake on the formation as the silicate is squeezed through the perforations. This filter cake forms a barrier which, in turn, prevents further flow of silicate into the formation. This effectively limits the depth of penetration of the silicate into the formation while still providing a good seal against flow through the squeezed perforations.

Well treatment method using sodium silicate to seal formation

A squeeze cementing method wherein the well tubing does not have to be pulled from the well so no workover rig is needed; a smaller volume of squeeze cement is required; the pressures involved in the squeeze operation can be precisely controlled with no risk of fracturing the formation; and there is no need for any drilling operations to remove hardened cement remaining in the well casing. More specifically, the present invention provides a squeeze cement operation that is carried out with a coiled tubing. The wellbore is isolated adjacent the perforations by flowing a packing fluid having a density greater than the cement through the coiled tubing to fill the lower part of the wellbore. An incompressible loading fluid is then flowed onto the packing liquid and this is followed by pumping the squeeze cement down the coiled tubing. After the cement is placed, a contaminating liquid is flowed down the coiled tubing to mix with the cement left in the casing and prevent it from setting. The contaminated cement and packing liquids are then removed from the casing which is then reperforated and returned to production.

Squeeze cement method using coiled tubing

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Anchorage, AK, United States of America

Gary D Herring