Table 2The formation fluid properties of Halfaya oilfield.four.three. Shale HydrationAccording towards the formation character, the Nahr Umr Shale is abundant in microfractures; the formation is broken, plus the drilling fluid can effortlessly flow to the micro fracture plane, which results in the adjust selleck bio of formation strength. EPZ-5676 clinical So as to prevent wellbore instability, the drilling fluid residence really should be enhanced. The influence of drilling fluid on the wellbore stability is analyzed through the mineral composition, the drilling fluid consistency, as well as the influence with the drilling fluid on formation strength.Tables ?Tables33 and ?and44 illustrate the minerals and clay minerals composition and material from the Nahr Umr Shale, respectively.
The check leads to the tables demonstrate that the Nahr Umr Shale primarily includes quartz and clay, in particular quartz, which exceeds 48.
5%. For shale Formation, the larger the quartz, the higher the brittleness; in the similar time, the content material on the clay minerals in the shale belongs to medium and small substantial level. The clay minerals mainly consist of illite/smectite and kaolinite, and the written content of smectite is lower. The sort of the clay mineral indicates the shale is quite brittle. On top of that, the kaolinite is a stable clay mineral, as well as hydration in the illite/smectite is additionally feeble. The variety and content material of your clay minerals the two indicate that Nahr Umr Shale Formation is actually a tricky and brittle formation and that is hard to hydrate.Table 3Mineral composition and material of your NahrAdapalene Umr Shale.Table 4Clay mineral composition and content of your Nahr Umr Shale.
According to investigation experience, in case the drilling fluid inhibition is very good enough, a formation such as the Nahr Umr Shale is impossible to hydrate devoid of growth collapsing. As a result, we assess the rejection capacity of 3 drilling fluid methods which are utilized in the Halfaya Oilfield. The three drilling fluids are natural salt drilling fluid, Gel-polymer drilling fluid, and KCl-polymer drilling fluid.The densities of these three sorts of drilling fluid are all one.33g/cm3; then we measured the cuttings recovery (The 40g cuttings with 3.2~2.0mm diameter injected on the 350mL fluid. Roll 16h inside a set temperature. Then filter the cuttings by way of a sieve. Dry and weigh cuttings to calculate the cuttings recovery.) and swelling ratio of those three drilling fluids.
The outcomes are shown in Table five.
The outcomes demonstrate the cuttings recoveries of these three varieties of drilling fluid are each greater than 95% for that Nahr Umr Shale; although the swelling ratios are different. These effects demonstrate the inhibitive capacity in the drilling fluid is excellent ; however, the outcomes indicate that the formation hydration is feeble. The inhibitive capability on the drilling fluid isn't the primary explanation for the wellbore instability from the Nahr Umr Shale.