Overview of the lightweight oil-well cement mechanical properties for shallow wells

Lightweight oil-well cement eliminates the need for the much expensive and problematic multi-stage cementing approach for isolating shallow intervals. However, the generally low compressive strength of lightweight cement in comparison to the neat cement recipes has been a major concern for operators who consider compressive strength the most important parameter. lightweight cement exhibit other desirable mechanical properties that affect the long-term integrity of the cement sheath. The objective of this review is to present laboratory and field investigations on the performance of different lightweight systems. According to field and laboratory investigations, a high compressive strength should not be of much concern, especially for shallow and weak formations where compressive strength higher than the formation can be deleterious. A minimum compressive strength of 50 psi is sufficient to support the casing. About 250–1000 psi is adequate to meet the requirement of many operations. Besides, foamed, perlite, zeolite, gilsonite, and microsphere-based cement exhibit adequate early age compressive strength and more important mechanical properties such as high tensile strength, low Young modulus, and high Poisson ratio which increase cement elasticity. With the enhancement in the mechanical performance of lightweight cement containing metakaolin and vermiculite, both calcined clays, it is recommend to inverstigate the use of calcined bentonite clay as supplementary cementitious material.