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"ADA" Pressure MIT Table II

TABLE II


CASING VOLUME FACTOR   Fc

          2-3/8"  (4.6 or 4.7 lb./ft.)   .0217 cu. ft./ft.
          4-1/2"  (9.5 lb./ft.)          .0912 cu. ft./ft.
          5-1/2"  (13.0 lb./ft.)         .1387 cu. ft./ft.
          7"      (17.0 lb./ft.)         .2331 cu. ft./ft.


NITROGEN CYLINDER CAPACITY   Vcl   (vcl)

    Full "T" - 303 Cubic Feet          Full "K" - 228 Cubic Feet
    (Empty - 1.74 Cubic Feet)          (Empty - 1.53 Cubic Feet)


CYLINDER TEMPERATURE / PRESSURE CORRECTION (+10% Fill Cylinders)

           F          Full  "T"                  Full  "K"
            0          2,290 psi                  1,910 psi
           25          2,415 psi                  2,015 psi
           50          2,540 psi                  2,115 psi
           70          2,640 psi                  2,200 psi
           95          2,765 psi                  2,305 psi


QUANTITY CALCULATION

-  Determine the Calculated Achievable Test Pressure   Pt

-  Determine the Test Pressure Ratio          Rt  = 1 + Pt / 14.7

-  Determine the Wellhead Pressure Ratio      Rwh = 1 + Pwh / 14.7

-  Determine the Cylinder Compression Ratio   Rcl = Vcl / vcl

-  Determine the gas required in standard cubic feet

Vt = (D x Fc x Rt - d x Fc x Rwh) / (1 - Rt / Rcl)

   where:
   D  is depth to perforations or injection zone
   d  is depth to fluid
   Fc
is casing volume factor from table above

-  Determine the number of cylinders required (round answer up)

N = Vt / Vcl

   where:
   Vcl is cylinder capacity from table above

The assumption is made that all cylinders are "ganged".  Sequential cylinder use is more efficient, adds a safety margin, and is recommended.  It is also prudent to use at least 110% of calculated gas volume.  It should be noted that it is now common practice for nitrogen cylinders to be overfilled by 10% (a "+" is stamped in the neck area of such cylinders), thus adding an inherent gas volume safety margin when such cylinders are available.

The "ADA" Pressure MIT involves the use of high pressure gas.  High pressure gas is dangerous stuff; do not attempt the "ADA" Pressure MIT if you are not familiar with high pressure gas safety rules, procedures, and practices.  DO NOT USE OXYGEN as the high pressure gas for any MIT; it is a potentially deadly practice.

These calculations, and other "ADA" Pressure MIT calculations, have been automated by the authors in a Lotus 1-2-3 template, ADACALC 3.1.  ADACALC 1.0 was originally written in 1990, and version 2.0 was developed in late 1991, both for Lotus 1-2-3 Release 2.x.  ADACALC 3.0 was modified from the original code to run on Lotus 1-2-3 Release 9.0 or later in September, 2003, and ADACALC 3.1 is a refinement created in December, 2005, adding additional cylinder sizes and updating cylinder data tables to reflect current gas industry practice.  ADACALC 3.1 is available free of charge if you have a need for it, but certain restrictions apply (see the ADACALC help screens for details).  You can download it now in "zip" format from this page (easiest option); The zipped version consists of the ADACALC 3.1 template and a read.me file.  If you need WINZIP, see our downloads page.


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