Optimal phasing of charges in a perforating system and method

Abstract

An optimal perforating gun method for accurate perforation in a deviated/horizontal wellbore is disclosed. The method includes a gun string assembly (GSA) deployed in a wellbore with shaped charges arranged in rows in a cluster and a total number of the shaped charges is equal to a total number of the rows. A total number of charges for each cluster in a stage is selected with the best statistical probability for a desired number of perforations in the cluster. The number of charges and the number of rows per each cluster in a stage is optimized such that there is a maximum probability of perforating into a low compression region in an upward and downward direction.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation in part of U.S. application Ser. No. 15 / 080,251, filed Mar. 24, 2016, the disclosure of which is fully incorporated herein by reference.FIELD OF THE INVENTION[0002]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 arranging shaped charges in rows in a cluster for explosively perforating a well casing and its surrounding underground hydrocarbon bearing formation.PRIOR ART AND BACKGROUND OF THE INVENTIONPrior Art Background[0003]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 in...

AI Technical Summary

Benefits of technology

[0030]The present invention in various embodiments addresses one or more of the above objectives in the following manner. The present invention provides a system that includes an optimal phasing perforating phased gun system and method for accurate perforation in a deviated/horizontal. 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 b

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. 7,30

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