heat collapse
1.COS-2 is a graft modified product of cationic starch The mud characteristic of OGS-2 was evaluated in laboratory,the experimental results show that CGS-2 has the following properties:obvious filtration-reducing, reltively strong salt resistance and heat resistance abilities, and fairly good anti-collapse.
2.The PAMS(2 - acrylamido - 2 - methylpropanesulfonic acid/acrylic acid/acrylamide) copolymer drilling fluids were used in more than one hundred wells of Zhongyuan Oilfield from March in 1998 to the end of October in 2002. The application results showed that the PAMS copolymer drilling fluids had very good capacity in depressing filtrate loss, heat stability, inhibition, heat resistance and salt tolerance, protection against collapse, and stability of well wall.
