ABSTRACT
The importance of drilling fluid cannot be overlooked in the drilling oil wells. Drilling fluids have different properties which need to be improved or put in check in order to successfully drill a well. These properties include viscosity, gel strength, mud density, filtration etc.
This projectaims at converting readily available, cost effective local additive (i.e. African walnut shell) in other to test for its suitability in improving the various properties of drilling fluid. These tests can be easily conducted in the laboratory and they test can be categorized in to three which are rheology test, filtrate test and hydrogen ion test.
The methodology involves the preparation of the local additives (African walnut shell) by sun drying it and grinding it into very fine grains. Fresh mud was prepared and mud with (20g, 25g, 30g walnut shell as an additive) was also prepared and various test was carried out to determine the properties of all the samples.
The result gotten indicated that the index n for all mud samples exhibited pseudo plastic flow with n less than 1 for each mud samples and there was relative increase in the apparent viscosity, for fresh mud it was 22.5cp, for fresh mud and 20g, 25g and 30g of walnut shell the apparent viscosity increased to 3.5cp, 4.25cp and 5cp respectively as the concentration of the walnut shell was increased. There was also an increment in the plastic viscosity, gel strength, mud density and the filter caked formed as the walnut shell was increased. After filtration test was conducted it was observed that less fluid was lost as the concentration of walnut shell was increased. The pH of all the sample was 8. Which shows that it was an alkaline solution.
In conclusion it was observed that the presence of walnut shell greatly improved the rheological properties of the mud as the concentration of the walnut shell was increased. The API fluid loss values of walnut shell indicate a better fluid loss control property as compared to the base bentonite mud.
