Method for determining formation characteristics in a perforated wellbore

A method for determining formation properties in a subterranean formation penetrated by a wellbore, the wellbore having a perforation extending into the subterranean formation, comprising:

• determining a radial hole radius and length of the perforation;
• calculating an equivalent probe radius for the perforation;
• and
• using the equivalent probe radius as the radial hole radius in formation analysis calculations.

A method of formation analysis for a formation penetrated by a wellbore, comprising:

• a) creating a cylindrical hole extending through the sidewall of the wellbore, the cylindrical hole having a known radius and first length;
• b) calculating an equivalent probe radius based upon the hole radius and first length;
• c) conducting formation analysis tests;
• d) performing formation analysis calculations utilizing the equivalent probe radius in place of the hole radius, thereby calculating initial wellbore formation properties;
• e) extending the cylindrical hole further into the formation, thereby creating a second length;
• and
• f) repeating steps b) through d) using the second length thereby calculating extended wellbore formation properties.

A method of generating a reservoir property profile around a wellbore, comprising:

• sequentially extending a perforation to differing distances from the wellbore into the formation;
• calculating an equivalent probe radius (rpe) for each different perforation length based upon the perforation radius (rp) and the formation length (Lpf) in the formation using the following formula:
• rpe=SQRT[rp*(rp+2*Lpf)];
• conducting reservoir analysis tests at each different perforation length;
• performing reservoir analysis calculations using the equivalent probe radius in place of the perforation radius to determine reservoir properties at each of the different length perforations;
• comparing the reservoir properties for each of the perforation lengths;
• and
• generating a reservoir property profile at various distances from the wellbore.

A method of analyzing a formation penetrated by a wellbore, comprising:

• providing a perforation extending from the wellbore into the formation, the perforation having a hole radius and a hole length;
• calculating an equivalent probe radius for the perforation, based upon the hole radius and length and an equivalent probe radius formula;
• and
• performing conventional formation analysis calculations utilizing the equivalent probe radius in lieu of the hole radius.