Wellbore Plugging Using Hydrated Bentonite

Historically, the oil and gas industry has used cement to plug abandon wells. This has been an effective procedure to capping unwanted wells. In the recent past several companies and institutions have begun to look at an alternative method to plugging these wells. This method involves using bentonite clay, a very common material in oil & gas drilling. One of the major benefits include the cut in costs, however a chief concern is the effects of saline solution on the integrity of the bentonite plug. Hydrated bentonite was tested using a lab setup of four, 10'x4" stands of casing. Each casing was filled with approximately 66" of bentonite and then hydrated using ranging salinity brine water. The salinity ranged from fresh water to 50,000 ppm sodium chloride. The plugs were allow to hydrate for a month, then pressure tested. It was found that hydrated bentonite holds pressure even better in higher salinity then in lower salinity, diminishing the concern of bentonite performance in saline reservoir waters. Research will continue to be conducted on the effects of salinity on bentonite. Experiments will also test other industry concerns; the effects of crude oil and temperature on the integrity of the bentonite plugs.