Sulfonated asphalt

DETAILED DESCRIPTION What is claimed is: 1.
A well working fluid comprising a fluid medium and a sulfonated blend of from about 10:1 to about 5:1 parts by weight of asphalt to parts by weight of a hydrogenated conjugated diene-monovinyl aromatic copolymer substantially free of olefinic unstauration and wherein said copolymer contains a major proportion of monovinyl aromatic, said sulfonated blend being dispersed in said fluid medium and present in an amount sufficient to reduce the filtration loss of said well working fluid and inhibit shale and clay disintegration.
2.
The well working fluid according to claim 1 wherein said copolymer is a hydrogenated butadiene/styrene copolymer.
3.
A composition according to claim 1 wherein said sulfonated blend is an alkali metal salt of said sulfonate and said well working fluid is a water based drilling fluid composition comprising water and a sulfonated blend of asphalt and a hydrogenated conjugated diene-monovinyl aromatic copolymer.
4.
A composition according to claim 3 wherein said copolymer is a hydrogenated butadiene/styrene copolymer.
5.
A composition according to claim 3 wherein said sulfonated blend is an alkali metal salt sulfonate.
6.
A composition according to claim 5 wherein said alkali metal salt is a sodium salt.
7.
A composition according to claim 4 wherein the amount of sulfonated blend added to the drilling fluid ranges from about 1.
0 to about 10 pounds per barrel of drilling fluid.
8.
A process for producing a sulfonated asphalt which comprises sulfonating a feedstock blend of from about 10:1 to 5:1 parts by weight of asphalt to parts by weight of a hydrogenated conjugated diene-monovinyl aromatic copolymer containing a major proportion of monovinyl aromatic and which copolymer is substantially free of olefinic unsaturation with a sulfonating agent, neutralizing the resulting sulfonic acids with an alkaline neutralizing agent, separating the resulting sulfonated product, and drying the resulting separated sulfonated asphalt product