Designing Cement Slurries for Preventing Formation Fluid Influx After Placement

Abstract

fax 01-972-952-9435. AbstractFormation fluid influx into cement slurries immediately after placement presents not only a short-term problem, for example losing the slurry due to shallow water flows, but also presents a long-term problem, for example gas flow and pressure buildup behind the casing. It is critical that cement slurries be designed carefully when such problems are anticipated. Cement slurries that often offer the best solution to resist the formation influx are those that do not gel while being pumped then gel/set and gain strength rapidly once placed. These are sometimes referred to as "right-angle set" cements and should possess the following attributes in laboratory design testing:• Maintains a low rheological profile while pumping for lower ECDs. • Predictable thickening and set times.• Retains the ability to transmit hydrostatic pressure under static conditions until the cement is ready to gel/set. • Short gel to set time under static conditions, often termed "transition time." • Short waiting on cement (WOC) time.This paper shows that although a cement slurry having a "right-angle set" may ensure the first two benefits, it does not always guarantee the latter two when present behind a casing. For example, some slurries might reach thickening time and become unpumpable rapidly, but strength development may not occur until long afterward, due to a time lag between thickening and hydration time (set time) of cement. In such cases, slurry should be designed such that the thickening time and hydration time are essentially identical. Novel slurries that maintain low rheological profiles while the slurry is being placed, then set and gain strength quickly due to cement hydration afterward, have been developed for a variety of densities and downhole temperatures. Results from laboratory and related field case histories will be presented.

Experimental Study of Micro Silica Behavior and Its Effect on Iraqi Cement Performance by Using X-Ray Fluorescence Analysis

“…Later, it is subjected to 2 hours' test duration. At the end of test duration, a syringe is used to extract the free water separated at the top of cement slurry and the amount of water is measured in milliliters (ml) (Santra et al, 2007).…”

“…The greatest loading at which the cement specimen is broken is characterized as the cement's compressive strength (Santra et al, 2007)…”

“…That compound could be made from different ingredients with different percentage of weight with respect to the weight of cement in the grout mixture. Cement with a good compressive strength must be capable to resist hard and corrosive formations, lost circulation zone, carbon (IV) oxide and other toxic gas intrusion, and extremely high temperature (Santra et al, 2007;Awadh and Awad 2020). Silica Fume is utilized like material for supplemental cementations for increasing the strength and durability.…”

South Africa’s Technical Readiness to Support the Shale Gas Industry

“…• The use of right-angle setting slurries (Santra et al, 2007) will reduce the time gas can migrate within the unset cement. Such systems are applied across high-pressure gas zones; they can develop sufficient strength to hinder gas percolation (Sutton et al, 1982) (e.g.…”

Water-Gas Migration Control and Mechanical Properties Comparison With a Quick-Setting Slurry Design QSSD to Be Applied in a Production Cementing Job for Ecuador

“…A primary reason for the relatively low rate of success in water and gas influx control is the use of an incorrect candidate-selection process. Several authors have suggested procedures and guidelines for water and gas-influx control (Sutton, D. and Sabins, F. 1984;Santra, A. et al 2007). …”