Low density oil-based wellbore fluids and methods thereof
A wellbore fluid may include an oleaginous continuous phase; a non-oleaginous discontinuous phase; an emulsifier stabilizing the non-oleaginous phase within the oleaginous phase; a low density material selected and in an amount to result in a specific gravity of the wellbore fluid that is less than 0.83; and at least one rheology modifier selected to suspend the low density material within the wellbore fluid.
1. A wellbore fluid, comprising:
an oleaginous continuous phase;
a non-oleaginous discontinuous phase;
an emulsifier stabilizing the non-oleaginous phase within the oleaginous phase;
a low density material selected and in an amount to result in a specific gravity of the wellbore fluid that is less than 0.83; wherein the low density material is glass microspheres; and
at least one rheology modifier selected to suspend the low density material within the wellbore fluid; wherein the emulsifier comprises a alkoxylated ether acid.
2. The wellbore fluid of claim 1 , wherein the at least one rheology modifier suspends the low density material in the fluid such that there is less than a 0.1 change in specific gravity in a column of the wellbore fluid when static for one hour.
3. The wellbore fluid of claim 1 , wherein the rheology modifier is selected from one or more of polycarboxylic acids, polyamides, alcohol alkoxylates, amine alkoxylates, ethylene oxide/propylene oxide copolymers, or combinations thereof.
4. The wellbore fluid of claim 3 , wherein the rheology modifier comprises a polycarboxylic acid fatty acid.
5. The wellbore fluid of claim 4 , wherein the rheology modifier comprises a dimer poly-carboxylic C12 to C22 fatty acid, trimer poly-carboxylic C1 to C22 fatty acid, tetramer poly-carboxylic C12 to C22 fatty acid, or mixtures of these acids.
6. The wellbore fluid of claim 1 , wherein the wellbore fluid has a plastic viscosity of less than 40 cP.
7. The wellbore fluid of claim 1 , wherein the wellbore fluid has a Fann 35 reading at 3 pm ranging from 2 to 6 lbs/100 ft 2 .
8. The wellbore fluid of claim 1 , further comprising at least one of a fluid loss control agent, a bridging agent, and a viscosifier.
9. The wellbore fluid of claim 1 , wherein the alkoxylated ether acid comprises an alkoxylated fatty alcohol terminated with a carboxylic acid, represented by formula (III):
wherein R is C 6 -C 24 or —C(O)R 3 (where R 3 is C 10 -C 22 ), R 1 is H or C 1 -C 4 , R 2 is C 1 -C 5 and n range from 0 to 20.
10. The wellbore fluid of claim 1 , wherein the microsphere has a collapse strength of at least 5000 psi (34.5 MPa).