Direct Emulsion Drilling Fluids Prevent Salt Washouts or Losses for Better Fluid PerformanceDownload PDF
Prevent salt washouts and losses in unconventional salt section wells
Permian Basin, Texas
Salt section washouts and resulting mud weight gains historically take a major toll on drilling costs in the Permian Basin’s complex Salado formation. The source of the long-standing challenge is a combination of a shallower salt section and a deeper low-fracture gradient section. Now, however, significant cost reductions are being achieved with the Halliburton BaraShale™ Lite fluid system, which uses field brine and emulsified base oil to reduce salt washouts while maintaining a lower mud weight. In addition to addressing wellbore challenges, the system greatly reduces waste disposal costs and enables reuse in multiple well applications.
Conventional water-based fluid systems elevate drilling expenses in the Salado formation due to two key factors: salt washouts, which raise cementing costs, and the resulting brine saturation, which increases mud weight – leading to fluid losses and disposal requirements. The significance of the cost and the need for greater efficiency has grown with increased drilling intensity. Since completion and stimulation programs make up the bulk of a well’s cost, minimizing time and cost requirements to reach the reservoir has become paramount. Conventional drilling fluids and casing designs often do not achieve these goals. While evolving casing designs with fewer strings simultaneously expose salt sections and weak underlying loss zones, freshwater resources are increasingly limited and brine disposal costs steadily grow.
To meet these challenges, Halliburton screened several types of emulsifier additives to advance the design of an oil-in-water fluid formulation. The resulting fluid design, the BaraShale Lite fluid system, eliminates the issues of traditional water-based systems. A proprietary emulsifier combines a brine base fluid with oil in order to prevent salt washout and to lighten the mud weight to prevent lost circulation. With better solids management, the system lowers transport costs, and, because it can be used from well to well, disposal costs are greatly reduced or eliminated altogether.
Close collaboration with an early-adopting operator of this system ensured that more advanced testing was also performed. Field brine, a complex mix of salts, was tested in the formulation for compatibility. Corrosion levels were assessed and verified as safe.
The initial commercial application was executed with additional oversight from the operator and Halliburton fluids specialists. Batch mixes were carried out in a timely manner and drilling was commenced. Daily communications between the development team and field team ensured that multiple checks were made and actions taken to provide fluids that would be meeting all parameters throughout the first well. Multiple sections were drilled with this original mix, allowing for valuable comparisons to previous wells when the customer had utilized conventional fluids.
USD saved per well
reduction in waste haul-offs
USD saved for first 7 wells
The BaraShale Lite fluid system achieved the primary objective of reducing cost in all aspects of the drilling process. Aggregate cost savings of approximately USD 854,000 were realized for the first seven wells. This was mainly due to a 70 percent reduction in waste haul-offs, as well as savings from reduced washouts and lower cement volumes.
After this initial success, several other customers in the Permian Basin adopted the BaraShale Lite fluid system. Since BaraShale Lite fluid was used in these initial trial wells in 2017, this system has been used to drill approximately 100 wells in Texas and New Mexico. The system has continued to perform well, offering similar or greater savings for operators. In particular, it has reduced the number of casing strings compared to older well designs. Additional value was realized from reuse of the fluid for later wells or to dilute other systems.
Based on this track record and on detailed discussions with several operators, the aggregate value realized for the BaraShale Lite fluid system is estimated at approximately USD 15 million dollars to date. This savings has allowed for sustained activity and greater focus toward optimized well completion and stimulation techniques.