Many arguments have been raised over the years as to the superiority of ball activated circulating tools vs. dart activated counterparts or vice versa. There is no simple yes or no answer to this since many factors can influence the selection. This article is not intended to establish the superiority of one system
over the other because, there is no absolute best single solution for all the conceivable problems that can be encountered. Sometimes, a ball activated system provides the solution whereas at other times, a dart activated system may provide a more desirable
outcome.
The majority of ball or dart activated circulating tools currently in use in our industry comprise of a “main valve body” and a “catcher sub” as external components. The internal components of these tools generally comprise of sliding sleeve / spring systems.
The interaction of internal and external components is in such a way that once the sleeve is forced down and the spring is fully compressed, the internal and external ports line up, hence establishing communication between the inner part of the string and the annulus. Upon releasing of the force on the sleeve and by the force of the recoiling spring, the sleeve moves back upward, and the inner ports are sealed off from the outer ports, terminating communication between the inner part of the string and the annulus. Therefore, the key factor in the operation of the circulating tool is the successful arrival and proper seating of the activation device on the seat of the sleeve so as to cut off the fluid flow to the bit, forcing the sleeve to travel downward and divert the flow through ports. This is why the argument should be more in relation to what activation medium is more suitable for which situation rather than a blanket statement that dart or ball is a superior medium!
The most relevant factor to consider when choosing a circulating tool need not be whether to use the DSI PBL tool or some other “dart activated” circulating tool. Instead, the consideration ought to be with respect to the selection of the suitable activation medium to be used with the DSI PBL tool, most fitting to the anticipated drilling conditions and well parameters.
