Calcium bentonite based drilling mud with NaOH and Na2CO3 additives to improve the laboratory simulated cleaning process

Abstract In this study, a new drilling fluid was prepared using Ca–Bentonite with Na2CO3 and NaOH to improve drilling fluid capacity on hole cleaning. Three inclination angles were used in the current study (vertical angle, 45 , and 67 ) with two statuses of inner pipe rotating static and 120 RPM. Three sets of drilling fluid were prepared; Set 1 (22.5 g of Ca Bentonite), Set 2 (22.5 g Ca-Bentonite + 4 g NaOH +0.6 g Na2CO3) and Set 3 (22.5 g Ca-Bentonite + 4 g NaOH +0.8 g Na2CO3). The results reveal that using these additives leads to an increase in the yield point, apparent and plastic viscosities of drilling fluid which leads to improving the quantities of cuttings recovered. The maximum cutting recovery was gained using drilling fluid set 3 which is 76% at DRP = 0 for Limestone cuttings and it increased to 87% at 120 RPM. The increase in well inclination angle causes a reduction in the percentage of cuttings recovered up to the surface. The results also demonstrate that the prepared drilling fluid promotes limestone cutting recovery more than dolomite cutting in all inclination angle ranges and two inner pipe positions.