| abstract |
PROBLEM TO BE SOLVED: To make mud for excavation with only materials existing in the field without requiring mud-making materials such as bentonite, CMC and polymer agent. A mud film forming agent for drilling mud according to the present invention comprises a (co) polymer (x ′) having an unsaturated carboxylic acid and / or a salt (a) as a main structural unit. ) The weight average molecular weight Mw of the polymer (x ′) is 200,000 to 3,000,000. Here, the weight average molecular weight Mw of the single polymer was set to 200,000 to 3,000,000. When the weight average molecular weight Mw was less than 200,000, the amount of filtered water, which is an index of wall-forming property, slightly exceeded 5 ml. This is because the amount of filtered water greatly exceeds 5 ml. [Selection] Figure 2 |