Characterization of Surfactant-Enhanced Cement Fluid-Loss Additives

Abstract

Modified surfactants, in the form of ethoxylate-coated resins (ECR), serve as the foundation for fluid loss additive systems that are functional in a wide range of applications and environments. ECR's, when combined with polyvinyl alcohol, produce fluid loss additives that:are minimally retardive,can be placed in turbulent flow, andpossess anti-gas properties. Blending ECR with hydroxyethylcellulose yields a multi-purpose fluid loss agent with higher efficiency, greater salt tolerance, and improved thermal stability as compared to conventional fluid loss additive systems. Presented are the laboratory data substantiating the use of surfactant enhanced fluid loss additives, as well as supportive case histories demonstrating the utility of these systems in field cementing operations. Introduction Fluid loss control agents are commonly employed in field cementing operations to lower the rate of cement filtrate loss under dynamic (and static) conditions. In the presence of differential pressure, filtrate loss to permeable strata can dramatically alter the physical properties of oil well cements. Thickening time, rheology, and mud displacement efficiency are all impacted by the changes in the water-cement ratio brought on by the loss of cement filtrate. As the liquid phase of the cement passes into the formation, a deposited layer of solids (filter cake) is formed on the formation face. Fluid loss additives function primarily by promoting the deposition of a low permeability filter cake, thereby limiting the rate of filtrate loss to permeable strata. The uncontrolled loss of filtrate during the cementing operation can result in:job failure due to dehydration of the cement into an unpumpable state;high equivalent circulating densities;an increased likelihood of annular gas migration; orunsuccessful squeeze operations. After the cement has been placed, the continued loss of filtrate increases the solid-water ratio which impedes the transfer of hydrostatic pressure to the formation. This inability to transmit a full hydrostatic pressure prior to strength development is a primary cause of annular gas flow. P. 321^

Experimental Investigation on The Effect of PolyVinyl Alcohol on Cement Fluid Loss in Oil Wells

“…Moreover, they explained that fluid loss control additives are not suitable for primary cementing job, because of high density of cement slurry and harmful for formation water invasion by fluid filtrate from the cement slurry. As demonstrated in [7], the reasons for creating fluid loss at the time of pumping cement slurry were studied. These reasons were high cement slurry density, having gas migration, cement slurry dehydration and failure job of cementing or squeeze cementing.…”

The Use of Lightweight Cement Slurries and Downhole Chokes Improves the Success of Primary Cementing on Air-Drilled Wells

“…It, too, can be extended for use at greater depths. 10 The availability of the Type III cement, its lower cost, and its slurry properties prompted its initial implementation on surface and intermediate strings of casing for the operator. The success of these jobs established the foundation for the eventual application of Type III to the more challenging production strings of casing for this project.…”