The Effect of Long-term Shut-in Periods on Fracture Conductivity

Polymer residue is known to be a major cause of propped fracture conductivity damage. Many factors that can contribute to the significance of this damage are polymer type, initial and final polymer concentrations, breaker types and concentrations, formation mineralogy, bottom hole static temperature, shut-in time and fluid cleanup rates. Most fracturing treatments are designed with good fluid stability for a specific period of time that corresponds to the job pump time. It is then desired to break the fluid as quickly and completely as possible to facilitate rapid cleanup of the well and minimize conductivity damage. A common belief has been that if the treatment is shut-in in the reservoir too long, fracture conductivity damage may increase. This belief has led to operational completion practices that are costly and unnecessary. A laboratory study was conducted to study the effects of long-term shut-in periods of up to seven days. The results indicated that additional conductivity damage would not occur under the conditions tested. These observations resulted in changes in completion procedures that improved rig time efficiency for the completion of remotely locate offshore wells.