Shale hydration inhibition agent and method of use

A water-base drilling fluid for use in drilling wells through a formation containing a shale clay which swells in the presence of water, the drilling fluid comprising

• an aqueous based continuous phase
• a weight material, and
• a shale hydration inhibition agent selected from the group:
• H2N—CH2CH2—O—CH2CH2—NH2
• H2N—CH2CH2CH2—O—CH2CH2—O—CH2CH2CH2—NH2
• NH2—CH2—CH(CH3)—(O—CH2—CH(CH3))8—O—CH2—CH2—OCH3
• and mixtures of these,
• wherein the hydration inhibition agent is present in the drilling fluid in sufficient concentrations to reduce the swelling of the clay.

A method of reducing the swelling of shale clay encountered during the drilling of a subterranean well, the method comprising:

• circulating in the subterranean well a water-base drilling fluid including:
• an aqueous based continuous phase and
• a shale hydration inhibition agent having the formula:
• H2N—R—{OR′}X—Y
• wherein
• R and R′ are alkylene groups having 1 to 6 carbon atoms and
• x is a value from about 1 to about 25, and
• Y is an amine or alkoxy group, and
• wherein the shale hydration inhibition agent is present in sufficient concentration to reduce the swelling of the clay.

A method of reducing the swelling of shale clay encountered during the drilling of a subterranean well, the method comprising:

• circulating in the subterranean well a water-base drilling fluid including:
• an aqueous based continuous phase,
• a weight material, and
• a functionally effective concentration of a shale hydration inhibition agent selected from the group:
• H2N—CH2CH2—O—CH2CH2—NH2
• H2N—CH2CH2CH2—O—CH2CH2—O—CH2CH2CH2—NH2
• NH2—CH2—CH(CH3)—(O—CH2—CH(CH3))8—O—CH2—CH2—OCH3
• and mixtures of these,
• and wherein the shale hydration inhibition agent being present in a concentration sufficient to reduce the swelling of the clay.