Source code for pygeopressure.pressure.eaton
# -*- coding: utf-8 -*-
"""
Routines for eaton pressure prediction
Created on Sep 20 2018
"""
from __future__ import (absolute_import, division, print_function,
unicode_literals)
__author__ = "yuhao"
import numpy as np
[docs]def eaton(v, vn, hydrostatic, lithostatic, n=3):
"""
Compute pore pressure using Eaton equation.
Parameters
----------
v : 1-d ndarray
velocity array whose unit is m/s.
vn : 1-d ndarray
normal velocity array whose unit is m/s.
hydrostatic : 1-d ndarray
hydrostatic pressure in mPa
lithostatic : 1-d ndarray
Overburden pressure whose unit is mPa.
v0 : float, optional
the velocity of unconsolidated regolith whose unit is ft/s.
n : float, optional
eaton exponent
Returns
-------
ndarray
Notes
-----
.. math:: P = S - {\\sigma}_{n}\\left(\\frac{V}{V_{n}}\\right)^{n}
[4]_
.. [4] Eaton, B. A., & others. (1975). The equation for geopressure
prediction from well logs. In Fall Meeting of the Society of Petroleum
Engineers of AIME. Society of Petroleum Engineers.
"""
ves = (lithostatic - hydrostatic) * (v / vn)**n
pressure = lithostatic - ves
return pressure
[docs]def sigma_eaton(es_norm, v_ratio, n):
"""
calculate effective pressure with the ratio of velocity and normal velocity
Notes
-----
.. math:: {\\sigma}={\\sigma}_{n}\\left(\\frac{V}{V_{n}}\\right)^{n}
"""
return es_norm * (v_ratio)**n
[docs]def power_eaton(v_ratio, n):
"""
Notes
-----
.. math:: \\frac{\\sigma}{{\\sigma}_{n}}=
\\left(\\frac{V}{V_{n}}\\right)^{n}
"""
return (v_ratio)**n