Experimental investigation of a smart LCM using a high- temperature flow loop for geothermal drilling

Document Type

Conference Proceeding

Publication Date

1-1-2021

Abstract

Lost circulation presents challenging issues in drilling operations, especially in high-temperature and fractured formations. Lost circulation events increase the nonproductive time (NPT) and the total cost of drilling operations. In some severe cases of high or total losses, well control is jeopardized, leading to a loss in lives and resources. Therefore, selecting a suitable lost circulation material (LCM) and an optimized fluid formulation is vital to the success of a lost circulation remedy. This paper introduces and studies a new smart material for dealing with lost circulation in geothermal drilling applications. The proposed material is a thermoset shape memory polymer (SMP) that activates at high temperatures (+150°) and increases its particle size to seal large fractures. A large-scale high-temperature (HT) flow loop has been built to investigate the impact of SMP particles on the mud rheological behavior at high temperatures. The annular flow of SMP mud was studied to confirm the SMP activation process. The SMP transportation was also compared with other conventional lost circulation materials such as walnut and cedar fiber. Different test parameters were considered in studying the LCM dispersion, such as its concentration, annular velocity, and pipe rotation. The results show that the smart lost circulation material can be activated at high temperatures (above 150°) to seal complex fractures efficiently. The activation process was confirmed by the 80-100 % increase observed in the LCM particle size. The mud sample containing the smart LCM is a non-Newtonian fluid with a strong shear-thinning behavior that is favorable in drilling operations as it makes the wellbore frictional pressure drops less sensitive to the increase in flow rate (shear rate). The pipe rotation and annular velocity were found very effective in dispersing the LCM particles into the mud stream to improve the sealing efficiency and avoid any complications that may arise from the deposited particles. The smart LCM outperformed cedar fiber and walnut in terms of suspension behavior, making it a suitable candidate for treating lost circulation in geothermal wells.

Publication Source (Journal or Book title)

Transactions - Geothermal Resources Council

First Page

567

Last Page

577

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