Lost circulation, where drilling fluid is lost to the formation, is one of the oldest challenges that drillers face. Dealing with lost circulation is one of the biggest contributors to increased non-productive time and cost during drilling. Unfortunately, there has been little innovation to combat this problem. A recent American Association of Drilling Engineers paper by Eric van Oort (UT-Austin), Innovative lost circulation control methods: managed temperature drilling, thermal wellbore strengthening and OBM/SBM-to-cement conversion (AADE-18-FTCE-121) looks at two new processes that can help with lost circulation prevention and recovery.
The first process involves increasing wellbore and nearby rock formation temperature to thermally strengthen the wellbore. The second involves solidifying oil-based and synthetic-based mud and using the resulting hardened product as a lost circulation material. While the two technologies are different in practice, they both rely on new chemistries to provide solutions for aiding lost circulation control.
Changes in near-wellbore temperature can have a substantial effect on stress distribution near the wellbore. However, providing the method to heat the wellbore has proved problematic. Solutions such as surface heating of the drilling fluid, using a downhole circulating sub or downhole electrical heating have proven expensive or impractical. Chemical heating provides a realistic alternative. The first lost circulation method discussed in the paper involves using calcium and magnesium salts with chlorine and bromine to create an exothermic reaction downhole, heating and strengthening the nearby wellbore. Common coating of the salts, in a practice borrowed from the pharmaceutical industry, can be used to control the time of the dissolution downhole and place the created heat at the zone of interest.
The second method uses alkali-activated materials, often referred to as geopolymers, to harden oil- or synthetic-based mud for use in mitigating lost circulation. Geopolymers can withstand the high levels of contamination that OBM/SBM can produce when used with traditional Portland cement. The geopolymer-OBM/SBM blend strengthens the cement, mitigating many cement-related issues including lost circulation. The one challenge is that geopolymers are typically found in construction-type cement, not the Portland cement that is standard in the oilfield.
Panther Fluids has the experience to select the right system to combat lost circulation. Our total fluids management approach means that we consider all variables, including formation, drilling system, drilling parameters and budget, for every well on which we provide services. We manage all fluids-related activities including the mud system, chemicals and additives, solids control and haul off and disposal. Panther takes care of the details so you can focus on drilling the well.