Optimal phasing of charges in a perforating system and method

Abstract

An optimal phasing perforating phased gun system and method for accurate perforation in a deviated / horizontal wellbore is disclosed. The system / method includes a gun string assembly (GSA) deployed in a wellbore with shaped charges in clusters. Within a cluster, the charges are separated into individual banks with a phase angle between the charges in each bank and an offset angle between banks. The number of charges per cluster, the phase angle and the offset angle are optimized such that there is a maximum probability of perforating into a low compression region in an upward and downward direction.

Description

FIELD OF THE INVENTION[0001]The present invention relates generally to perforation guns that are used in the oil and gas industry to explosively perforate well casing and underground hydrocarbon bearing formations, and more particularly to an optimally phased perforating apparatus for explosively perforating a well casing and its surrounding underground hydrocarbon bearing formation.PRIOR ART AND BACKGROUND OF THE INVENTIONPrior Art Background[0002]During a well completion process, a gun string assembly is positioned in an isolated zone in the wellbore casing. The gun string assembly comprises a plurality of perforating guns coupled to each other either through tandems or subs. The perforating gun is then fired, creating holes through the casing and the cement and into the targeted rock. These perforating holes connect the rock holding the oil and gas and the well bore. “During the completion of an oil and / or gas well, it is common to perforate the hydrocarbon containing formation w...

AI Technical Summary

Benefits of technology

[0022]Provide for efficiently reducing tortuosity and energy loss in a perforation tunnel with minimum number of shots per foot.

[0023]Provide for longer extension of fractures which have minimal tortuosity with minimum number of shots per foot.

[0024]Provide for the highest and optimal injection rate per perforation tunnel so that a maximum fracture length is realized with minimum number of shots per foot in a cluster.

[0025]Provide for improving the probability to at least 50% for perforating within +−15° of the upward and downward low compression region.

[0026]Provide for an optimal phasing of the charges in the perforating gun per cluster in order to achieve maximum perforation and fracturing efficiency.

Problems solved by technology

However, horizontal wellbores are often deviated as much as 100 ft in any direction over the length of 3 miles.

The charges in the gun may or may not be optimally phased when perforating.

If all perforations are involved, and the perforations are shot with 0°, 60°, 90°, 120°, or 180° phasing, multiple fracture planes may be created, leading to substantial near wellbore friction and difficulty in placing the planned fracturing treatment.

However, the chances of perforating in an upward and downward direction are low when the well casing is deviated and the perforating gun is not horizontal.

There is an accuracy issue of positioning the guns (orienting) with respect to the up / down vector.

Field results indicate that even with orientation of the guns, operational issues can cause perforations in a non-preferred region.

However, since the wells are not perfectly horizontal and in most case deviated, the gun (0411) may be rotated as illustrated in FIG. 4 (0420) and the charges (0404) may be perforating into the high compression region or sideways and produce ineffective fracture treatment.

Some of the perforation tunnels cause energy and pressure loss during fracturing treatment which reduces the intended pressure in the fracture tunnels.

Therefore, if any perforation does not participate, then the incremental rate per perforation of every other perforation is increased, resulting in higher perforation friction.

The phase angle is set based on the minimization.” However, U.S. Pat. No. 7,303,017A does not teach an optimal phasing of the charges in the bank so that charges perforate within desired perforation angles in a low compression region especially for a deviated well.

The prior art as detailed above suffers from the following deficiencies:Prior art perforation phasing systems do not provide for efficiently reducing tortuosity and energy loss in a perforation tunnel with minimum number of shots per foot.Prior art perforation phasing systems do not provide for longer extension of fractures which have minimal tortuosity with minimum number of shots per foot.Prior art perforation phasing systems do not provide for the highest and optimal injection rate per perforation tunnel so that a maximum fracture length is realized with minimum number of shots per foot in a cluster.Prior art perforation phasing systems do not provide for achieving a probability greater than 50% for perforating within +−15° of the upward and downward low compression region.Prior art perforation phasing systems do not provide for an optimal phasing of the charges in the perforating gun per cluster in order to achieve maximum perforation and fracturing efficiency.Prior art perforation phasing systems do not have an optimal statistical chance of perforation placement when less than or more than 6 shots are placed in a cluster.

While some of the prior art may teach some solutions to several of these problems, the core issue of reacting to unsafe gun pressure has not been addressed by prior art.

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