Bentonite continues to rank second in quantity only to barite as a mud additive, as shown in Fig. 11-2.14 In spite of the partial replacement of bentonite by polymers in some muds, about 1,160,000 short tons (1,050,000 tonnes) of swelling-type bentonite, with a well-site cost of roughly $120,000,000 (check also oil well drilling well cost per foot), was used …Web