Page 48 - Petroleum and Gas Field Processing

(v) Steps (ii)–(iv) are repeated for various expected values of
W.C. and GOR, and for various producing conditions
(natural flow and artificial lift)
(vi) On the P wf –q plot, the intersection of the OPR curve for a
particular tubing–flow line combination and producing
conditions with the IPR curve of any specific time
represents the maximum possible production rate and
corresponding P wf . If the OPR curve does not intersect
with a particular IPR curve, then the well will not flow
when such an IPR and producing conditions are reached.
(vii) If possible, select the tubing–flow line combination whose
OPR curves intersects with present and all corresponding
future IPR curves and provides values for q that are
consistent with the planned production strategy.
(viii) When more than one tubing–flow line combinations are
possible, select the one that provides the best economics.

Determining Tubing Grade and Weight
Once the tubing size has been determined, the next step is to determine the
grade and weight of the tubing. Similar to casing, tubing grade refers to
the type of steel alloy and its minimum yield strength. Tubing are available
in the same grades as casing (i.e., H-40, J-55, N-80, C-75, L-80, and
P-105). Other high-strength grades that are resistance to sulfide stress
cracking are also available.
To determine the tubing grade and weight, the maximum collapse
and burst loads that act on the tubing are first calculated and multiplied
by a safety factor. These values are then used to make an initial selection
of tubing grade and weight that provides sufficient collapse and burst
resistance. With the selected weight, the tension load is calculated
and multiplied by a safety factor. This is then compared to the tensile
strength of the selected tubing. The selected tubing is accepted if its tensile
strength matches or exceeds the tensile load. Otherwise, another grade
and/or weight are selected and the calculations are repeated until a final
selection is made.

1.8.3 Completion and Workover Operations
Completion and workover operations are basically similar. However, they
are given different associations based on when the operation is performed.
Completion operations are any and all operations performed on the well
to get if ready for production. Workover operations, however, refer to

Copyright 2003 by Marcel Dekker, Inc. All Rights Reserved.