MULTIFUNCTION DRILLING FLUID IMPROVES CEMENTING QUALITY

Mineral slag is a potential water hardening material. adding a little of fine mineral slag into water base drilling fluid,a multifunction drilling can be produced.While cementing,the multifunction drilling fluid and mineral slag with activator of proper quantity added can constitute a solidifying liquid used for cementing. This paper presents the performance of multi function drilling fluid and solidifying test,diffusion test of actvator in solidifying liquid of slag drilling fluid and tests for compressive strength, rheology, stability, initial and final setting time and sulfate resistance. It is regarded that the multifunction drilling fluid can be solidification while keeping for a long time under downhole condition;the activator can diffuse into the filter cake and undisplaced multi function drilling fluid to promote the solidification;the slag cement slab is resistant against corrosion of sulfate to meet cementing requirement;and the multi function drilling fluid can improve cementing quality, particularitly for cementing of long reach wells and horizontal wells.