Development and Application of a New Drillable Openhole Bridge Plug

The basement reservoir is distributed predominantly in Northern Slope Belt of Bongor basin in Chad and adopts openhole completion. Layered well testing is performed in basement reservoir to acquire fluid property, find water-oil interface, confirm oil production rate, etc. Sometimes more than two layers will be tested one by one from the bottom up in the openhole interval. Cementing plug technology is often applied to seal the tested zone and the cement plug also makes a new bottom hole for the MFE testing string to reduce the tail pipe length. But the fractures of basement openhole interval are well developed, so cement slurry leakage often occurs and makes it difficult to control the top of the cement plug, which makes a low success rate while cementing plug. Repeatedly cementing plug operations for one layer makes testing period and cost increased. In order to solve the aforementioned problems and through investigating and analyzing the basement reservoir lithology, a new type of tool, drillable openhole bridge plug, is developed after many laboratory experiments. It is combined with cementing plug to seal the tested zone and successfully used in six (6) wells, simplifying the plugging technology for basement openhole well, raising the success rate of plugging operation and making the plugging position more accurate.