Question

a) Discuss the effect that crushing (out of roundness) caused by poor handling will have on the performance properties of casing.

b) Explain the following Special Cementing Problems and how these problems can be solved.

i. Salt Sections Formations

ii. Kicks Following Cementing.

iii. Cement lost circulation.

  

c) Explain the advantages and disadvasntages of using a liner rather than a full length casing string.

  

d) A well is being planned for the Arab sea. A 16.8-lb/gal pore pressure (BHP) is expected at 14,000 ft, which is the target pay zone. An intermediate casing string is set at 12,000 ft in a 17.8-lb/gal fracture gradient formation. The mud weight is expected to be 0.3 lb/gal heavier than the maximum pore pressure (16.8 lb/gal).

The company's philosophy with respect to cementing is to cement the entire annular area to surface with slurry that weighs 1.0 lb/gal above the maximum mud weight. Due to pumping time restrictions in this high-BHT well, the fluid must be displaced at 6 bbl /min, which will create an equivalent circulating density of 0.4 lb/gal.

i. Can the company's standard cementing philosophies be used in this well?

  

ii. If not, calculate the amount (height) of cement weighing 1.0 lb/gal in excess of mud weight that can be used without causing lost circulation

Answer 1

b.)iAns: Salt section FormationsTHE form OF SALT:There be three main forms of salt:

1. Halite, or astound salt, form in either thin or huge layer. It occur as a relatively soft white rock, with red or yellow coloring caused by impurities.

2. Anhydrite occur lengthily in beds connected with halite deposit. It is harder plus less soluble than halite and harder in addition to denser than gypsum. It often occurs as rubbery, granular or more compact masses.

3. Gypsum is basically the hydrated version of anhydrite. It generally occurs in beds associated with layers of halite and dolomite.

Salt is remarkably a lesser amount of impenetrable than other sedimentary rocks.

As a result, salt deposits tend to flow under pressure, compare with either folding or fault, which occur with lithologies such as sandstones and shales.

brackish mobility occurs due to the divergence in density between the salt and any surrounding sedimentary formations.

These properties of salt lead to several distinct drilling challenge:This includes

• opening tiptoe – Salt may extrude (or “tiptoe”) into the wellbore unpaid to its synthetic nature.

This creep can potentially cause stuck pipe and tiredness damage to the drillstring.

The tempo of creep resolve depend on the specific properties of the salt, pressure and temperature. An increase in the last two tends to increase rate of tiptoe.

• disappointment – Salt is soluble. Under convinced situation, brackish will become softer and effect in borehole rise. This cause erratic directional tendency, unfortunate BHA performance and stability issues.

• Formation pressure issues – During the formation of domes, the salt may “drag” extremely buried formations faster to the surface as the artificial salt rise, bringing their analogous formation pressure.

These uncharacteristic pressure can grounds unpredicted overbalanced or underbalanced drill conditions.

• debris zones/sutures – These are normally connected with salt domes and can present performance problems (e.g., vibrations), especially whilst drill bits are old inSent on:6:56 pm