New Phase Transformation Fluid Based Loss Circulation Material: Hi-Strength, Year Round Use to Cure Severe to Total Loss in Reservoir and Non Reservoir Sections

Abstract

Loss zones are present all over the Arabian Peninsula geology. A fluid loss event not only causes non-productive time but also significantly increases the overall operations cost. With this motivation, we developed a completely new solution that is recommended for partial to total losses situations and useable year round for all zones including the reservoir section. This paper presents the science behind this new phase transformation fluid technology. The new loss circulation material (LCM) was designed to be pumped easily, achieve thixotropic behavior under down-hole conditions resisting LCM from losing in thief zone prior to getting it set as a rigid plug with high compressive strength. This fluid phase transforming behavior is a result of pseudo-crosslink chemistry which differentiate this system from other commonly available solutions which are resin based or uses fibers or other network creating additives. Selective use of chemistry and additives used in the formulations changes the phase of fluid from easily flowable (allow pumpability using normally available surface equipment) to a thixotropic gel (to aid particulate carrying), from a low viscosity (enable formation entry) to a final hi-strength set material. Thixotropy could be customized by varying the salt concentration. Salt tolerance gives the formulation compatibility with sea water. Thus LCM could be formulated with fresh water or the sea water. Fluid which is easily pumpable phase transforms to thixotropic fluid which helps carry the particulate content to the target zones. Customized setting control additive concentration ensures that LCM does not prematurely setup. Finally a high compressive strength solid plug is formed which can withstand the losses of fluids to the formation. High strength above 500 psi was measured. This LCM is a fit for purpose technology with over 90% acid solubility which favors its use in reservoir section to minimize formation damage. If needed, LCM could be cleaned up using post-job acid flush.

A Novel Solution for Severe Loss Prevention While Drilling Deep Wells

“…The shear thinning was represented by a viscosity decrease with increasing shear rate, and such behavior resulted from the polymer molecules alignment [40]. The shear thinning during the fluid pumping is achieved by means of mixing of a novel amphoteric surfactant with sealant powder [41]. The thixotropic shear shinning behavior of the HSLCM provides many benefits such as placing the fluid downhole easily, preventing the gas migration, and reducing the fluid flow to the thief zones before the material solidification.…”