Chapter 2 Pressures Flashcards
Pressures
List the most common drilling fluid functions?
- Remove cuttings from the well
- Control formation pressures
- Suspend and release cuttings
- Seal permeable formations
- Maintain wellbore stability
- Minimize reservoir damage
- Cool, lubricate, and support the bit and drilling assembly,
- Transmit hydraulic energy to tools and bit
- Ensure adequate formation evaluation
- Control corrosion
- Facilitate cementing and completion
- Minimize impact on the environment
True or False:
When saltwater contaminates an oil base mud the density will decrease?
True
What is the advantage of using oil-based mud over water-based mud?
- Well stability is improved,
- Clays do not hydrate and swell,
- Production is improved from sandstones containing clays,
- Problems are reduced when drilling evaporated,
- Wellbore enlargement is reduced,
- Mud properties are more stable, and
- Contamination resistance is increased.
What hole angle and mud weight might you start to see barite sag issues?
Directional wells of >30degs inclination drilled with mud densities of >1440kg/m3 are likely candidates for sag problems.
What are three factors that increase the potential of barite sag? How should they be mitigated?
- Hole angle - Well Planning,
- Low annular velocities-higher pump rates and/or less annular clearances,
- Low viscosity clean muds-mud conditioning and treatment.
What three well control values can we obtain by using the SIDPP in the calculations?
- Formation Pressure
- Mud Density Increase
- Initial Circulating Pressure
Why is the RSPP used in well kill operations?
Killing a well at the reduced speed slows the choke operator to make choke adjustments in a more controlled manner. In addition, the RSPP pump rate directly affects the gas rate limit that is allowed to flow through the surface equipment system and degasser.
When should the RSPP be taken?
- After every 150m of new hole,
- After a drill string change,
- After a nozzle size change,
- After change in mud properties,
- After changing the mud pump’s liners and pistons
Sag is most often associated with well angles of 50degs to 80degs, low annular velocities and low viscosity clean muds. Possible problems include?
Lost circulation, Stuck pipe, Pack offs, Wellbore instability, and Well control problems.
Four hole cleaning ranges based on hole angle have been identified are: Near Vertical I - 0-10 degs Low II - 10-30 degs ???? - ???? High IV - 60-90 Degs
Intermediate III - 30-60 degs
Sliding tendencies start dissipating at angles greater than?
About 60 degs, due to the corresponding decrease in the gravitational force vector.
The validity of the SIDPP should be verified prior to the completion of any calculations. The essential components to accurately determine SIDPP used to calculate FP are?
- The drill string must be full
- The drill string must be on bottom,
- The drill string must be full of a known density fluid,
Annular Pressure Loss (APL) is defined as the ?
Friction pressure that develops from the drilling fluid passing between the drill string and the wellbore.
Factors that affect circulating pump pressure?
- Density of the mud,
- Type of substance,
- Roughness of the surfaces making contact,
- Surface area in contact,
- Direction of movement,
- Velocity,
- Mud rheology
The main factors effecting ECD’s are?
-Hole Depth, Hole size, Hole condition, Drill string geometry, Circulation rate, Pipe rotation, Mud weight, Mud rheology, Quantity of drilled cuttings in the annulus.
Factors affecting “Swab Pressures” include?
Hoisting speed, Hole clearance, Mud properties (Density does not effect swab pressures), Balled-up bit and/or BHA, Nozzle size, Could increase inside casing
When displacing a well from a heavy mud to a light mud while maintaining constant bottom hole pressure, what should be done?
A pressure schedule must be prepared and followed during the displacement to ensure Applied Surface Pressure is incrementally added as the light mud is placed in the wellbore.
Why is it good practice to rotate the drill string while conducting a flow check?
Break gels in mud to get the most accurate flow check as possible.
Gas to surface (Pressure inversion) Bottom Hole Pressure ?
Formation Pressure + Hydrostatic Pressure
Gas Migration rate of rise is effected by?
- ANGLE OF THE HOLE,
- The properties of the influx,
- Mud properties,
- The eccentricity of the hole,
- The size of the annulus
Describe the Maximum Allowable Casing Pressure (MACP)?
It is the maximum casing pressure (CP) that can be applied at surface without fracturing any formation below the casing shoe or exceeding the burst rating of the casing, wellhead or BOP’s.
Describe the wells swab kick tolerance?
The wells swab kick tolerance is based on a kick volume with an equivalent mud density equal to or less than the mud density in the hole.
True or False: Determine the number of bottles required by dividing the required accumulator size by the bottle size and subtracting One Gallon (3.785L) for each bottle to account for the bladder displacement?
True.
True or False: When determining the number of back nitrogen bottles required for a BOP stack. You use the 50% safety factor?
False: You figure out the liters Without the 50% safety factor.
