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 in an amount to result in a specific gravity of the wellbore fluid that is less than 0.83; wherein the low density material comprises glass microspheres, and
at least one rheology modifier to suspend the low density material within the wellbore fluid, wherein the rheology modifier comprises a dimer poly-carboxylic C12 to C22 fatty acid, a trimer poly-carboxylic C12 to C22 fatty acid, a tetramer poly-carboxylic C12 to C22 fatty acid, or mixtures of these acids.
2. The wellbore fluid of claim 1 , wherein the at least one rheology modifier suspends the low density material in the wellbore 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 wellbore fluid has a plastic viscosity of less than 40 cP.
4. The wellbore fluid of claim 1 , wherein the wellbore fluid has a Fann 35 reading at 3 rpm ranging from 2 to 6 lbs/100 ft 2 .
5. The wellbore fluid of claim 1 , further comprising at least one of a fluid loss control agent, a bridging agent, and a viscosifier.
6. A method, comprising:
circulating a wellbore fluid in a wellbore, wherein
the wellbore fluid comprises:
an oleaginous continuous phase;
a non-oleaginous discontinuous phase;
an emulsifier stabilizing the non-oleaginous phase within the oleaginous phase;
a low density material in an amount to result in a specific gravity of the wellbore fluid that is less than 0.83; wherein the low density material comprises glass microspheres, and
at least one rheology modifier to suspend the low density material within the wellbore fluid, wherein the rheology modifier comprises a dimer poly-carboxylic C12 to C22 fatty acid, a trimer poly-carboxylic C12 to C22 fatty acid, a tetramer poly-carboxylic C12 to C22 fatty acid, or mixtures of these acids.
7. The method of claim 6 , wherein the wellbore fluid is circulated while drilling through a depleted reservoir.
8. The method of claim 6 , further comprising stopping circulation of the wellbore fluid while the wellbore fluid is present in the wellbore.
9. The method of claim 8 , wherein after stopping circulation of the wellbore fluid, the wellbore fluid has less than a 0.1 specific gravity change in the wellbore.
10. The method of claim 6 , wherein the wellbore fluid has a plastic viscosity of less than 40 cP.
11. The method of claim 6 , wherein the wellbore fluid has a Fann 35 reading at 3 rpm ranging from 2 to 6 lbs/100 ft 2 .