Lost-circulation materials (LCMs) are often used to mitigate the loss of drilling fluids into subterranean formations. Well-known LCMs include ground marble, graphitic carbon, and cellulosic particulates. The carrier fluid's ability to suspend the LCM material is critical in high-pressure/high-temperature (HP/HT) or inclined wells. This paper provides methods to help determine and manage suspension characteristics of LCMs in the fluid with the aid of certain suspending agents (e.g., fibers).

A detailed experimental study was conducted to evaluate the suspension of a range of LCMs in various drilling fluids and investigate the effects of suspending agents (e.g., fibers) on LCM suspension. Based on experimental data, semiempirical models were developed to help predict the influence of fibers on LCM suspension. The design parameters used in these models included fiber concentration, fiber density, number of fibers per unit volume, and average fiber length and diameter. The modeling work discussed in this paper also provides methods for tailoring the suspending agent properties necessary for achieving effective LCM suspension in the fluid.

The uniform suspension of LCM in the carrier treatment or drilling fluid is necessary during LCM pill preparation and during wellbore applications, such as a hesitation squeeze operation. Thus, using fibers to manage the suspension characteristics of LCM in carrier fluids can help ensure efficient use of LCMs for lost-circulation control. This method is particularly important in severe-loss zones where large sized LCMs are used as well as in HP/HT or inclined wells where maintaining LCM in suspension can be challenging.

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