Do casing design for the following $8\mathrm{.}5$ in vertical well based on burst, collapse, and tension in the

most cost$-$effective way. Safety factors for tension, collapse, and burst are $1\mathrm{.}5,1\mathrm{.}125,$ and $1\mathrm{.}1,$

respectively. We only have $K55,23\frac{lbf}{ft}$ and $L80,29\frac{lbf}{ft}$ with buttress $($BUTT$)$ thread type in our

stock. Your design will be used to purchase casing strings for the $200$ wells required to develop

the field. Also, calculate how much your company will save if you do a multi$-$string design versus

a single$-$string one.

Note I: We will run a $7"$ production casing from the surface to $9,000ft$ depth.

Note II: The well will be put on a gas lift later in its lifespan.

Note III: The well will be stimulated using the hydraulic fracturing technique.

Note IV: The density of the water$-$based fracturing fluid is $8\mathrm{.}4\frac{lbm}{\text{g}\text{a}\text{l}}.$

Note $V$ : The density of the completion fluid is $10\mathrm{.}6\frac{lbm}{\text{g}\text{a}\text{l}}.$

$CSD=9,000ft$

$\frac{d{P}_p}{dD}=0\mathrm{.}55\frac{}{ft}$

$MW=10\mathrm{.}8-11\mathrm{.}2ppg$

$F.G.=0\mathrm{.}71\frac{}{ft}$

Casing $OD=7in$

Gas Gradient $=0\mathrm{.}15\frac{}{ft}$