How can I stay within the window to maintain well control while avoiding fluid losses and formation damage?
Activities such as circulating fluids, running and landing casing and liners, and cementing contribute to a pressure in the wellbore that can be expressed in terms of equivalent circulating density (ECD), which is additional pressure to the formation that can induce fractures and lost circulation. The objective of ECD management is to stay within the pore pressure and fracture gradient window to mitigate these issues.
Specific drilling challenges include having fluid systems capable of maintaining the hydrostatic pressure of the fluid column, while avoiding barite sag or lost circulation.
Other challenges involve running and landing casing and liners to depth while avoiding increased surge pressures and slow pipe-running speeds. An additional issue is achieving complete slurry placement to enable cement sheath integrity. This involves reducing the pressure drop across the liner top during circulation and increasing annular clearance and optimized flow paths throughout the annulus with good stand off to prevent bridging, pack off, or inefficient displacement.
Halliburton offers a comprehensive well construction solution to help manage equivalent circulating density during drilling, casing or liner deployment, and cementing operations. This solution includes a suite of both new and existing technologies that enable operators to achieve operational efficiencies and increased safety while managing cost. Halliburton’s new Low ECD Solution helps operators address these challenges by:
- Increasing bypass flow area to improve circulation rates and displacement efficiency while not exceeding the fracture gradient of the formation due to pressure build-up
- Reducing overall fluid viscosity to reduce frictional forces
- Maintaining hydrostatic pressure of the fluid column below the fracture gradient while maintaining well control
- Minimizing surge pressures across formations while maximizing running speed of the casing or liner by reducing the pressure drop across the hanger helping to prevent fluid loss
- Allowing drilling fluids, spacer and cement to flow freely into the casing and up the annulus to avoid lost circulation, while also providing excellent hole cleaning
- Drilling fluids modeling software can predict the influence of pump output and pipe rotation on drilling performance under a variety of conditions and evaluate available drillstring sizes for optimal hole cleaning and hydraulics.
- Conduct predictive-analysis simulations of complex fluid-flow interaction and displacement scenarios before cementing operations.