For gravel-packing, Schlumberger recommended ClearPAC HT fluid, formulated for use with screens employing Alternate Path technology at BHST between 200 and 300 degF [93 to 149 degC]. Unlike alternative fluid options for suspending proppant at very low rates in that temperature range, ClearPAC HT fluid is nondamaging and compatible with the relatively inexpensive, locally available calcium chloride (CaCl2) brine. This compatibility improved logistics and lowered fluid costs for the operator.
To avoid fracturing the reservoir with a narrow frac window of approximately 150 psi, careful fluid design was critical to minimize friction pressures and still suspend the gravel. Because of its superior proppant-carrying capability compared with conventional VES at high temperatures, the ClearPAC HT fluid was designed with lower viscosity, which also helped reduce friction pressures. The real-time mixing capability eliminated the requirement for rig tanks or huge tank volumes for batch mixing, thereby saving time on the rig and improving fluid quality.