Method of formulating and using a drilling mud with fragile gels

A method for conducting a drilling operation in a subterranean formation using a fragile gel drilling fluid comprising:

• (a) an invert emulsion base;
• (b) one or more thinners;
• (c) one or more emulsifiers;
• and
• (d) one or more weighting agents, wherein said drilling fluid is visco-elastic.

A method for drilling a borehole in a subterranean formation using a fragile gel drilling fluid comprising:

• (a) an invert emulsion base;
• (b) one or more thinners;
• (c) one or more emulsifiers;
• and
• (d) one or more weighting agents, wherein said drilling is in deep water and the ECDs are less than about 0.5.

A drilling fluid comprising:

• (a) a continuous invert emulsion base comprising a blend of esters and olefins, wherein said esters are selected from the group consisting of about C12 to about C14 fatty acids and 2-ethyl hexanol, about C8 fatty acids and 2-ethyl hexanol, and combinations thereof, and said olefins are selected from the group consisting of isomerized olefins and internal olefins each having about 40 to about 70 weight percent C16 and about 20 to about 50 weight percent C18;
• (b) one or more thinners derived from fatty acids;
• wherein said thinners are selected from the group consisting of:
• thinners having the following general formula:
• R—(C2H4)n(C3H6O)m(C4H8O)k—H, where R is a saturated, linear alkyl radical having about 12 to about 14 carbon atoms, n is a number ranging from about 1 to about 10, m is a number ranging from about 0 to about 10, and k is a number ranging from about 0 to about 10;
• thinners comprising a non-ionic surfactant which is a reaction product of ethylene oxide, propylene oxide and/or butylene oxide with C10-22 carboxylic acids or C10-22 carboxylic acid derivatives containing at least one double bond in position 9/10 and/or 13/14 having units of the general formula:
• where R1 is a hydrogen atom or an OH group or a group OR2, where R2 is an alkyl group of about 1 to about 18 carbon atoms, or an alkenyl group of about 2 to about 18 carbon atoms or a group of the formula:
• where R3 is a hydrogen atom, or an alkyl group of about 1 to about 21 carbon atoms or an alkylene group of about 2 to about 21 carbon atoms;
• and combinations thereof;
• (c) one or more emulsifiers derived from fatty acids;
• (d) one or more weighting agents;
• and
• (e) at least one additional additive compatible with said ester blend wherein said additive is selected from the group consisting of additives for filtration control, additives for high temperature high pressure control, and additives to reduce or control temperature rheology.

A fragile gel drilling fluid comprising:

• (a) an invert emulsion base;
• (b) one or more thinners;
• (c) one or more emulsifiers;
• and
• (d) one or more weighting agents, wherein said fluid is visco-elastic.