Retrievable bridge plug and retrieving tool

A retrievable bridge plug apparatus for isolating a zone down a borehole, comprising:

• a) a mandrel body portion having left and right threaded connections on end portions of the mandrel body portion;
• b) a retrieving tool attached to the lower end of a string of tubing and secured to the upper portion of the mandrel body;
• c) slip members on upper and lower ends of the mandrel body portion moveable to sealingly engage against the wall of casing when sufficient weight is brought to bear on the mandrel body portion by lowering the tubing string;
• d) flow ports in the mandrel body for allowing fluid circulation through the tool for cleaning the slip members prior to disengagement from the casing;
• and
• e) means for disengaging the slip members on the mandrel body from against the casing wall by the movement of the tubing string, so that the tool may be retrieved from the borehole.

A method of setting and retrieving a bridge plug apparatus in a borehole, comprising the following steps:

• a) providing a bridge plug and lowering the bridge plug down a cased borehole from a retrieving tool;
• b) applying sufficient weight on the bridge plug for engaging a set of lower slips against the wall of the casing;
• c) applying additional force on the bridge plug for engaging a set of upper slips against the wall of the casing;
• d) causing rubber members to expand against the wall of the casing so as to effect a fluid seal between the bridge plug and the casing;
• e) allowing fluid to circulate through the bridge plug for cleaning any foreign material from the upper slips;
• f) reattaching the retrieving tool to the bridge plug;
• g) disengaging the upper and lower slips from the casing;
• h) allowing the rubber elements to retract from against the wall of the casing;
• i) pulling the bridge plug from the hole with the retrieving tool.