Abstract: A method and composition for distinguishing native hydrocarbons in a formation from oil-based drilling fluid with nuclear magnetic resonance (NMR) is provided so that NMR may be used in analyzing formation fluids from boreholes drilled with oil-based drilling fluids. In the method, the drilling fluid is doped with oil solubilized paramagnetic species before or during drilling of the borehole. The paramagnetic species cause a shift in the T1 and T2 NMR response of the drilling fluid.

Abstract: In one embodiment, the present invention provides a drilling fluid composition that comprises a surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and emulsion facilitating particles. In another embodiment, the present invention provides a method of treating a subterranean formation comprising providing a treatment fluid that comprises a surfactant-free emulsion, the surfactant-free emulsion comprising an oleaginous fluid, a fluid that is at least partially immiscible with the oleaginous fluid, and emulsion facilitating particles; and treating the subterranean formation.

Abstract: The invention provides aqueous based well drilling and servicing fluids containing a polymer viscosifier with enhanced thermal stability provided by a diacid or diacid salt preferably having about two to about eight carbon atoms, such as, for example, sodium oxalate. The invention also provides a method of enhancing the thermal stability of aqueous based well drilling and servicing fluids containing a polymer viscosifer by adding diacid or diacid salt to the fluids.