An Alternate Cementing System For Low Pressure Formations In Canada

Abstract

A new light weight blended cement has been de-developed in Canada for solving a series of oper-ational problems for cementing across low pres-sure formations were foam cements are usually applied. The slurry density can be varied from 1,100 to 1,400 Kg/m This system imparts good slurry properties such as uniform cement column density, zero free wa-ter, non-settling, reliable rheology, fluid loss and thickening time control behaviors. During the transition from liquid to solid state, the system develops stable gel strength, high shear bond strength, and high compressive strength even at low temperatures. References and illustrations at end of paper In field applications, the system reduces signif-icantly equipment and manpower requirements when compared with foam cementing job oper-ations, and can eliminate the need for a stage collar. No cement fall-back has been seen after implementing more than 25 jobs. Case histories including an on-site computer job record are dis-cussed. INTRODUCTION Light weight cements are solutions for cement-ing across rock formations which are fractured or having a low Eracture gradient, highly perme-abable, vuggy or cavemous. These weak forma-tions usually have very low pressure that they may not be able to support the hydrostatic pres-sure from a collumn of normal cement slurries.