1) A wellbore is drilled first vertically to the point h of depth D=9,000ft, and then extends
in the horizontal direction y. The rock formation is fully isotropic and homogeneous
everywhere with constant OBG = 18 lbm/gal, PPG = 9 lbm/gal, and Poisson's ratio V =
0.35. The horizontal in situ stresses in the x-y plane are equal.
(a) Determine the effective compressional stresses at points A, B, E, and F, for mud weight
of MW=11 lbm/gal and for the following two cases:
i. Permeable wellbore wall
ii. Impermeable wellbore wall
(b) Determine the minimum rock compressive strength, CS (psi), that would allow for a
minimum of 1.5 lbm/gal mud weight window (MWW) in the horizontal section of the well
for the following two cases:
i. Permeable wall
ii. Impermeable wall
(c)Using the CS_s that you have obtained in part b, determine the MWW of the vertical
section at D1=5000 ft for both the permeable and impermeable borehole wall conditions.
+ 1° x
2) The well plan calls for a Type IV Directional-Horizontal well with horizontal section at the
target depth of TVD = 11,500 ft.
Design the well survey with the following information:
KOP = 10,000 ft
Expected build rate = 7°/100 ft
Note: You may need to consider a build-tangent-build scenario, in which case
Tangent angle = 50°.
3) Casing having an OD of 9.625 in. and an ID of 8.535 in. is to be cemented at a depth
of 12,900 ft in a 12.25-in. borehole. A 40-ft shoe joint will be used between the float collar
and the guide shoe. If is desired to place 2,400 ft of cement in the annulus. Each sack of
Class H cement (SG=3.14) will be mixed with 4.1 gal of water to which is added 16 %
calcium chloride salt (by weight of water). Compute the density of the slurry, the yield of
the slurry, the number of sacks of cement required. Use an excess factor of 1.5. The salt
will be added to the water phase and thus does not blend with the dry cement.
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