Non-toxic, inexpensive synthetic drilling fluid

A wellbore fluid comprising:

• (a) at least one additive selected from the group consisting of emulsifiers, wetting agents, viscosifiers, weighting agents, fluid loss control agents, proppants for use in hydraulically fracturing subterranean formations, and particulate agents for use in forming a gravel pack;
• and
• (b) a synthetic fluid selected from the group consisting of (A) synthetic fluids having (I) a pour point greater than about -30.degree. C. (-22.degree. F.) and (II) a cetane index greater than 50, and comprising (i) at least about 95 weight percent hydrocarbons containing 11 or more carbon atoms, (ii) greater than 5 weight percent hydrocarbons containing 18 or more carbon atoms, (iii) at least about 50 weight percent isoparaffins, (iv) at least about 80 weight percent total paraffins, (v) less than 10 weight percent naphthenics, (vi) less than 0.1 weight percent aromatics, and (vii) at least 2 hydrocarbons containing a consecutive number of carbon atoms, and (B) synthetic fluids comprising (i) at least about 95 weight percent hydrocarbons containing 10 or more carbon atoms and (ii) at least about 90 weight percent n-paraffins.

A method for treating a well, the method comprising the step of injecting a synthetic fluid into the well, where the synthetic fluid is selected from the group consisting of (A) synthetic fluids having (I) a pour point greater than about -30.degree. C. (-22.degree. F.) and (II) a cetane index greater than 50, and comprising (i) at least about 95 weight percent hydrocarbons containing 11 or more carbon atoms, (ii) greater than 5 weight percent hydrocarbons containing 18 or more carbon atoms, (iii) at least about 50 weight percent isoparaffins, (iv) at least about 80 weight percent total paraffins, (v) less than 10 weight percent naphthenics, (vi) less than 0.1 weight percent aromatics, and (vii) at least 2 hydrocarbons containing a consecutive number of carbon atoms, and (B) synthetic fluids comprising (i) at least about 95 weight percent hydrocarbons containing 10 or more carbon atoms and (ii) at least about 90 weight percent n-paraffins.

A method for drilling a borehole in a subterranean formation, the method comprising the steps of:

• (A) rotating a drill bit at the bottom of the borehole;
• and
• (B) introducing the water-base drilling fluid of claim 32 into the borehole (i) to pick up drill cuttings and (ii) to carry at least a portion of the drill cuttings out of the borehole.