Multi-Stage Displacement System
The TETRA Designed Spacer Pill (TDSP™) system is designed for wellbore cleanup of water-based, as well as diesel oil-based and synthetic oil-based muds. The TDSP spacer system is applicable in situations requiring segregation of fluids due to environmental considerations.
The TDSP spacer system requires pumping the three spacers outlined below. Each spacer is specifically designed by your TETRA fluids specialist to perform one of the three displacement processes and maintain compatibility with the fluids it contacts.
TDSP™ I: The Mud Displacement Stage
TDSP I spacer, a weighted spacer pill designed to act as a piston within the wellbore, pushes the drilling fluid ahead of it, relying on yield point, gel strength, density, and apparent viscosity to maintain its integrity as it travels through the wellbore. TDSP I spacers effectively prevent the channeling of fluids.
TDSP I incorporates a blend of polymers and a variety of weighted material specially formulated to fit the given circulating temperature and density requirements. The TDSP I spacer provides a minimum of1,000 feet of coverage and requires a minimum of five minutes’ contact time. It is thermally stable up to 450°F/232°C.
TDSP™ II: The Surfactant Wash Stage
TDSP II spacer is a turbulent flow spacer containing concentrated surfactants, specifically designed for the mud type used, that disperse any residual mud from tubular surfaces. The TDSP II spacer provides a minimum of 2,000 feet of coverage and requires a minimum of 10 minutes’ contact time in the largest annular section of the wellbore. While maximum pumping rates are often limited by pump capabilities, an annular velocity of 180 ft/min is recommended in each annular interval.
The TDSP II spacer is designed to ensure that sufficient TDSP II is available to disperse the entire volume of drilling mud residue. For best results, we’ll work with you to perform tests on a sample of the mud from the wellbore.
TDSP™ III: The Viscosified Sweep Stage
The TDSP III spacer, a blend of polymers and thermal stabilizers, is used after the TDSP II surfactant wash and before reintroducing clear brine fluids to the well. This stage removes any residual materials remaining in the wellbore, and warns the rig crew that brine is about to return, giving them time to divert returns once residue has circulated out of the well.
Like TDSP I spacer, the TDSP III spacer has rheological properties that maintain its integrity while it travels through the wellbore, which minimizes the chance of it commingling with the completion fluid. Individual stage volumes physically separate the brine, protecting it from mud contamination; allows adequate contact time with the wellbore to efficiently clean it; and to carry residual solids out of the wellbore.
TETRA Oil Mud Detergent (OMD)
A dispersant, TETRA OMD cleans casing and tubing of water-based and oil-based mud residue during the displacement of mud by a clear brine completion fluid. TETRA OMD is also effective at cleaning oil mud residue from rig mud pits and surface equipment prior to reintroducing clear brine fluids.
TETRA O-Sol Surfactant Wash
A proprietary blend of surfactants, TETRA O-Sol wash disperses and removes oil-based and synthetic oil-based muds. It is also part of the TDSP II O-Sol surfactant wash formulation.
A proprietary blend of surfactants and solvents, TETRASol removes hydrocarbons, oil-based materials, pipe dope, asphaltenes, and resins from metal surfaces. As a concentrate, it is used in both onshore and offshore rigs to remove diesel oil-based muds from the wellbore prior to introducing completion fluid.