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Improved Ball Dropping Process

IP.com Disclosure Number: IPCOM000218052D
Publication Date: 2012-May-16
Document File: 6 page(s) / 332K

Publishing Venue

The IP.com Prior Art Database

Abstract

When using ball droppers during well servicing, the dropper assembly can be exposed to pressure spikes that may damage the dropper. A method for reducing the pressure spikes transmitted to the ball dropper is described. The method consists of using a Flow Control Choke to dampen the pressure spike before it reaches the dropper and reduce the volume of compressible fluid in the well bore and dropper assembly. A recommended work method for preventing pressure spike damage while dropping balls is also described.

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Improved Ball Dropping Process

When using ball droppers during well servicing, the dropper assembly can be exposed to pressure spikes that may damage the dropper. A method for reducing the pressure spikes transmitted to the ball dropper is described. The method consists of using a Flow Control Choke to dampen the pressure spike before it reaches the dropper and reduce the volume of compressible fluid in the well bore and dropper assembly. A recommended work method for preventing pressure spike damage while dropping balls is also described.

Introduction

In well construction and well servicing processes balls are often used to actuate tools located in the wellbore. These balls may be inserted into the wellbore using a ball dropping device (Figure


1). Once inserted into the wellbore, the balls are pumped from the surface down to seat in a downhole tool. During the dropping and pumping process, the dropper assembly can be exposed to pressure spikes which may damage the device. A method for controlling and minimizing the pressure spikes transmitted to the ball dropper is described. This pressure control method helps prevent damage to the equipment.

Cause for and Damage from Pressure Spikes

Pressure spikes can occur when:


1. The isolation valve between the wellbore and dropper assembly is opened


2. The pumping rate changes

3. A ball seats in a sleeve.

If air is contained in the dropper assembly when a pressure spike occurs, the air compresses resulting in an increase in fluid velocity around the balls. This velocity may lift a ball in the dropper resulting in an impact between the ball and the hook located above the ball. Examples of damaged hooks from a ball dropper are shown in Figure 2.

Flow Control Choke

By adding the device illustrated in Figure 3 known as a Flow Control Choke (FCC), the pressure spikes that would normally occur can be dampened before they reach the dropper. The FCC is positioned directly below the ball dropper in the string of equipment mounted to the wellhead. The FCC is a modified plug valve which contains an orifice drilled through the closed portion of the plug. When in the choked position the FCC dampens wellbore pressure spikes, thereby, protecting the ball dropper assemblies. The unchoked position allows for the balls to pass through the FCC. Pressure transducers can be installed on either side of the FCC. For maximum protection the FCC should only be rotated to the unchoked position when the differential pressure across it is low.

Reduced Air Volume

Since damage may result from the flow of liquid as it displaces compressed air, further protection is provided...