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Progress in Petrochemical Science

Wellbore Cool Down During Hydraulic Fracturing Simplifies Using Dissolvable Materials

Submission: May 04, 2018; Published: May 18, 2018

DOI: 10.31031/PPS.2018.02.000528

ISSN 2637-8035
Volume2 Issue1


Dissolvable materials are enabling a revolution in the completion and stimulation of wellbores. Effective design of dissolvable fracturing tools, however, needs to account for the substantial cooling effect that arises during pump down and stimulation. The degradation process, degradation time, and material properties change because of the wellbore cool down. A well bore cools when fluids are injected into the formation. Temperature profiles are measured with fibre-optic cable and are simulated with numerical models. Both measured and modelled results show that down hole temperatures can be cooled to near surface temperatures. This temperature data is combined with experimental dissolution behavior to show that different dissolution behaviour occurs during pump down, setting, wellbore stimulation, and wellbore temperature recovery.

The actual temperature that fracturing tools will experience during their useable life depends on wellbore cool down and can be much less than the static formation temperature. All dissolvable materials have dissolution rates and material properties that are temperature dependent. Some dissolvable plastics will not degrade at lower temperatures. Measured and modelled cool down from hydraulic fracturing are used to show the temperature profile during different operational stages. The greatest temperature cool down occurs while the dissolvable fracturing tool is isolating a zone during the fracture treatment. This temperature cool down also occurs during the only time of the operation in which the fracturing tools are required to maintain a significant differential pressure. The temperature cool-down effect becomes more significant as more zones are fractured and more fluid is injected into the formation. Dissolvable fracturing tools should be designed for the temperature experienced during wellbore cool down rather than the static formation temperature. Both field data and numerical modelling show that a dynamic temperature estimation is more accurate than static bottom hole temperature (BHT) at predicting the temperature experienced by dissolvable fracturing tools. The cool down of the wellbore is an important design parameter for the materials and construction of dissolvable tools.

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