ANALYSIS OF THE CASING DAMAGE CAUSES IN THE EVAPORITE BED OF JIANGHAN OILFIELD

Large scale of evaporite bed exists in Jianghan oilfield, and as many as 82 rhythmites formed by the e-vaporite beds and shales stretch along the ordinate,while there are multiple pressure layers. During well cementing in this area, cement channeling usually occurs due to the non-regular hole diameter in the evaporite bed,which results poor cementing quality and finally leads to serious casing damage. Adjustment wells have to be drilled to renew the abandoned because of casing damage in this area. The casing damage causes and their mechanisms is investigated and analyzed by the way of geomechanics, from such aspects as rock characteristics, casing string design in the evaporite bed,and cementing quality. Some recommendations and remedial measures are presented, and this provides a theoretical background for evaluation of evaporite bed creeping and accurate casing designing.