Case Study: Analyzing Bottomhole Temperature Gauge Data in Gulf of Mexico Frac Packs to Optimize Fracture Fluid Crosslink, Stability and Break Times

摘要

The crosslinkers, buffers and breakers that are used in fracturefluid designs have typically been tested with emphasis placedon break time. Fracture fluids for high permeabilityformations need to be designed for multiple purposes:wellbore crosslink time, stability, and break time. Crosslinktime in the wellbore is critical for fracture propagation.Stability is critical for proppant transport. Break time iscritical for proper cleanup of the fracture fluid so thatproppant-pack conductivity is maximized. It is important thatthese times are based on the correct temperatures.Fracture fluid additives have primarily been based onbottomhole static temperature (BHST) or some portion ofBHST. The wellbore temperature while pumping is typicallycooler than BHST. Crosslink and stability time should bebased on the cooler wellbore temperature. Test temperaturefor break time, on the other hand, should be based ontemperature in the fracture once the treatment has beencompleted. Therefore, a fluid design needs to effectivelysatisfy: 1) crosslink time at a cooler wellbore temperaturewhile pumping, 2) stability time at a cooler wellbore and insitufracture temperature while pumping, and 3) break time ata temperature closer to bottomhole static temperature oncepumping has ceased.This paper analyzes the bottomhole gauge data from over50 frac packs in the Gulf of Mexico. The data was evaluatedby identifying the maximum cool down while pumping andidentifying the percentage of temperature increase aftertreatment. The BHST's ranged from 122°F to 262°F. Theobjective is to evaluate the design temperature so that therecommended fracture fluid will have an effective crosslink inthe cooled-down workstring, stability for proppant transport,and an effective break time upon completion of thefracture treatment.