Session: 11-04-02 Well Cementing Theory&Practice-2

Paper Number: 104992

104992 - Development of High-Density Self-Healing Cement 

Pressure and temperature changes during the life of the well (drilling/production) cause some casing-casing pressure leaks in the annulus between casings, thereby indicating that the well barriers could not isolate all the zones and subsequently resulting in the migration of the fluid to the surface. Such wellbore isolation prevent us from taking full potential of our high performance wells. 

Under most improper wellbore integrity conditions, the tensile strength of cement has a greater impact on its failure as compared to the cement’s compressive strength. Consequently, increasing tensile strength of cement is a higher priority than increasing its relative compressive strength. This can be achieved by using additives such as latex, polyvinyl alcohol or fibers, or simply by increasing cement flexibility. The objective of this paper is to discuss the development, testing, and field execution of a new high density type of cement, self-healing durable cement, to mitigate such failures due to pressure or temperature cycling.

This new cement was developed utilizing novel components that results in a cement with a reduced Young’s modulus. A lower Young’s modulus makes the cement more elastic to resist pressure and temperature cycling, absorb applied stresses, and prevent cement cracks. The developed self-healing durable cement also provides an additional benefit of mechanical properties enhancement as the included additive exhibits swelling and sealing capacity when contacted by hydrocarbon fluids. In the event cracks form in the cement, this will be a path for the fluid to trigger the swelling and self-healing mechanism.

The paper includes detailed testing data for thickening time, rheology, free water, settling at different ranges of densities. An additional test was also included to evaluate the durability of the system with time. Mechanical properties testing was performed for cement samples after 10, 20, and 30 days curing at representative targeted field conditions. Single-stage triaxial tests were performed on dry cement core plugs to measure static and dynamic properties through ultrasonic and shear velocities. These properties were determined at confining pressures and included the Young’s modulus, the Poisson’s ratio, and Peak Strength.

The developed self-healing durable cement was applied for 13 3/8” casing covering oil bearing zones at lower densities. The deployments were declared successful since negative testing and temperature and pressure cycling did not result in any CCA. Ultimately, good cementing performance is always measured by having zero psi casing/casing annulus pressure.

Presenting Author: Vikrant Wagle Saudi Aramco

Presenting Author Biography: Vikrant Wagle is working as Science Specialist with EXPEC ARC, Saudi Aramco. He has done Ph.D. from University Institute of Chemical Technology, Mumbai India. He works in the area of development of new drilling fluids and cementing additives and systems.

Authors:

Abdullah S. Alyami Saudi Aramco
Vikrant Wagle Saudi Aramco