ÖzThe aim of this study is to determine the effect on the rheological and filtration properties of water based drilling fluid of boron minerals. For this purpose, water-based drilling mud was prepared and borax (Na2B4O7.10H2O) with a particle size of 45 μm, ulexite (NaCaB5O9.8H2O) with a particle size of 75 μm and colemanite (Ca2B6O11.5H2O) with a particle size of 100 μm with different concentrations 1-5 (% w/v) are separately added. The characterization of borax, uleksite and colemanite are examined using X-ray fluorescence spectrometer (XRF). The rheological properties such as apparent viscosity, plastic viscosity, yield point and gel strength of the developed mud systems adding boron minerals were determined with a FANN viscometer. The filtration properties were examined using an API Filter Press. All physical measurements were carried out according to the American Petroleum Institute (API) standards. Borax, ulexite and colemanite added (1-5% w/v) drilling muds rheological and filtration properties then compared to each other and the additive free water based drilling mud. The rheological and filtration properties of the developed mud systems are compared to original (additive free) mud system and with each other respectively. It is observed that boron additives improve the rheological properties of the drilling mud. Borax and colemanite have a better effect compared to ulexite. Filtration properties such as filtrate loss and filter cake thickness are increased compared to the original mud system but still in the reference value range and can be implemented to drilling operations.

Drilling mud have been the subject of constant study since they are the most costly item of oil exploration. Recently, the several additives have been added to improve the rheological properties of the drilling mud. In this study, a water based drilling mud that is (1, 2, 3, 4 and 5) (% w/v) of colemanite (Ca 2 B 6 O 11 .5H 2 O), which is a calcium borate group mineral in the particle size of 100 μm subscale, was prepared for this drilling mud. The rheological properties such as plastic viscosity (PV), apparent viscosity (AV), gel strength, water loss and cake thickness of the obtained drilling muds were analyzed in detail using Fann Viscometer and American Petroleum Institute (API) testing equipment. As a result of the study, it was found that the added colemanite had a positive effect on the rheological properties of the drilling mud. When the analysis results of the drilling muds obtained at different ratios of colemanite addition are compared with each other, it is found that 4% of colemanite-added drilling mud has the best properties (excluding gel strength). The water-based drilling mud prepared by adding colemanite has 30.4% cP of plastic viscosity; 63.6% cP of apparent viscosity; 140% of rupture point; gel strength (10-sec and 10-min) values compared to the water based drilling muds prepared without any addition was positively affected.