# Drilling Utilities

GeoNav is an Excel-based survey sheet that allows the user to input and calculate surveys and graph the actual wellpath. Formation tops can be overlayed to assist with geosteering.

## Calculators

HXR Pore Pressure Prediction Calculators (Copyright Traugott 2005)

Overburden Calculator – sand/shales
wd
airgap
depth
units ?
Uplift ?
OBG=
Pore Pressure Calculator – Eaton (calculate OBG first)
ITT

ITT(n) ?

‘x’

OBG ?

G(n) ?

PPG=

Fracture Gradient Calculator – no depletion, no tectonics
OBG

PPG

k ?

units ?
FPG=

Pore Pressure Calculator – 1d Model, no centroid effect
depth(1)

PPG(1)

depth(2)

units ?

Gint ?

PPG =

LOT (or PPG) converter from one water depth to another
LOT(1)

wd(1)

depth(1)

airgap

wd(2)

To get help, hover over a text box or click (?). For references, download (1) and (2).

Example 1: What is the PPG at 12000 feet if top of overpressure is at 4900 feet. To solve, using 1d Calculator, set depth(1) to 4900, PPG(1) to 8.9, depth(2) to 12000, and Gint to 1 psi/ft. (For metric, PPG(1) is 1.07 g/cc and Gint is 22.6 kPa/m.) Answer is 15 lbs/gal.

Example 2: What is the PPG at the top of a 500 foot gas column if the water/gas contact is at 3500 feet and if PPG is normal hydrostatic at the contact. To solve set depth(1) to 3500, PPG(1) to 8.9, depth(2) to 3000, and Gint to 0.1 psi/ft. (For metric set PPG(1) to 1.07 and Gint to 2.26.) Answer is 10.06 lbs/gal.

Example 3: What is the FPG at 4000 feet in 2000 feet of water if LOT in an offset well in 1000 feet of water is 17 lbs/gal at 3000 feet. To solve using LOT converter, set LOT(1) to 17, wd(1) to 1000, depth(1) to 3000, and wd(2) to 2000. Answer is 14.9 lbs/gal.