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Title: Method for interpreting well log records to yield indications of gas/oil in an earth formation such as a sandstone, limestone, or dolostone

Patent ·
OSTI ID:5738150

The present invention indicates that acoustic characteristics associated with a first well penetration a gas/oil-containing strata such as a sandstone, limestone or dolostone, can be normalized (and favorably compared) with similar characteristics of a second, contiguous well of known hydrocarbon potential, such characteristics being calculated and displayed by means of a machine-implemented data processing method in which well logging and geologic data are fed thereto to calculate such characteristics without the need for shear-wave velocities. In more detail, in accordance with the invention brine-saturated bulk and shear moduli, (i.e., Kw and Gw) of a sandstone, limestone or dolostone penetrated by the second well can be predicted as a funtions of, say, brine-saturated P-wave modulus (PW *) alone (independent of shear-wave velocity). In that way, resulting acoustic values including distinct velocity and amplitude values as a function of a saturation operator can ultimately be provided. Such values, when compared to actual, in-well, field-generated characteristics of the first well, are surprisingly accurate predictors of the amount of gas/oil maturation in and around the first well. The method has particular accuracy in designating gas zones within formations of interest due to use of the complete Benedict-Webb-Rubin non-ideal gas law in pseudo-reduced form.

Assignee:
Chevron Research Co.
Patent Number(s):
US 4399525
OSTI ID:
5738150
Resource Relation:
Patent File Date: Filed date 17 Aug 1981; Other Information: PAT-APPL-293540
Country of Publication:
United States
Language:
English