How do you design and implement a wellbore cleaning strategy for extended reach drilling (ERD)?

1 Wellbore geometry and trajectory

The wellbore geometry and trajectory of an ERD well affect the flow regime, the cuttings transport, and the pressure losses in the annulus. You need to analyze the wellbore profile, the dogleg severity, the inclination, and the azimuth to determine the optimal mud properties, flow rates, and nozzle sizes for effective hole cleaning. You also need to account for the effects of friction, gravity, and centrifugal forces on the cuttings behavior and the mud rheology.

2 Drilling fluid selection and management

The drilling fluid plays a vital role in wellbore cleaning and hole cleaning for ERD wells. You need to choose a fluid that has the appropriate density, viscosity, gel strength, and solids content to suspend and transport the cuttings out of the wellbore. You also need to monitor and adjust the fluid properties regularly to avoid deterioration, contamination, or barite sag. Additionally, you need to use proper filtration and solids control equipment to maintain the fluid quality and reduce the waste generation.

4 Drill pipe and casing selection and handling

The drill pipe and casing are the tubular components that connect the surface equipment with the BHA and form the wellbore structure. The drill pipe and casing selection and handling impact the wellbore cleaning and hole cleaning for ERD wells by affecting the annular clearance, the torque and drag, and the buckling risk. You need to choose drill pipe and casing that have the appropriate diameter, grade, connection type, and coating to suit the wellbore conditions and the drilling objectives. You also need to use proper handling techniques and equipment to avoid damage, wear, or corrosion.

5 Wellbore cleaning tools and procedures

The wellbore cleaning tools and procedures are the specialized devices and methods that are used to remove the residual mud, cuttings, cement, or debris from the wellbore before running the completion or performing a test. The wellbore cleaning tools and procedures are crucial for wellbore cleaning and hole cleaning for ERD wells, as they prevent formation damage, plugging, or leakage. You need to use wellbore cleaning tools that are designed for ERD wells, such as scrapers, brushes, magnets, or circulation subs. You also need to follow wellbore cleaning procedures that are tailored for ERD wells, such as high flow rates, multiple trips, or reverse circulation.

6 Wellbore cleaning evaluation and verification

The wellbore cleaning evaluation and verification are the processes that are used to assess the effectiveness of the wellbore cleaning strategy and confirm that the wellbore is clean and ready for the next operation. The wellbore cleaning evaluation and verification are essential for wellbore cleaning and hole cleaning for ERD wells, as they ensure that the wellbore cleaning objectives are met and that no issues arise during the completion or testing. You need to use wellbore cleaning evaluation and verification methods that are suitable for ERD wells, such as caliper logs, gamma ray logs, pressure tests, or inflow tests.