Table 2The formation fluid properties of Halfaya oilfield.four.3. Shale HydrationAccording on the formation character, the Nahr Umr Shale is abundant in microfractures; the formation is broken, as well as drilling fluid can conveniently flow to the micro fracture plane, which results in the change BIO GSK-3 GSK-3 inhibitor of formation strength. Adapalene In order to prevent wellbore instability, the drilling fluid house really should be improved. The influence of drilling fluid around the wellbore stability is analyzed in the mineral composition, the drilling fluid consistency, as well as the influence of your drilling fluid on formation power.Tables ?Tables33 and ?and44 illustrate the minerals and clay minerals composition and material in the Nahr Umr Shale, respectively.
The test results in the tables present the Nahr Umr Shale primarily consists of quartz and clay, especially quartz, which exceeds 48.
5%. For shale Formation, the higher the quartz, the increased the brittleness; at the very same time, the written content of the clay minerals in the shale belongs to medium and very little substantial level. The clay minerals mainly consist of illite/smectite and kaolinite, as well as material of smectite is very low. The kind of the clay mineral indicates that the shale is incredibly brittle. Additionally, the kaolinite is a secure clay mineral, and also the hydration in the illite/smectite is also feeble. The type and information of your clay minerals each indicate that Nahr Umr Shale Formation can be a really hard and brittle formation that is tough to hydrate.Table 3Mineral composition and content material with the Nahrselleck chemical Umr Shale.Table 4Clay mineral composition and content from the Nahr Umr Shale.
According to research experience, should the drilling fluid inhibition is great enough, a formation just like the Nahr Umr Shale is not possible to hydrate with no growth collapsing. For that reason, we assess the rejection capacity of three drilling fluid techniques that 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 3 varieties of drilling fluid are all 1.33g/cm3; then we measured the cuttings recovery (The 40g cuttings with three.2~2.0mm diameter injected to the 350mL fluid. Roll 16h in the set temperature. Then filter the cuttings by means of a sieve. Dry and weigh cuttings to calculate the cuttings recovery.) and swelling ratio of these three drilling fluids.
The results are shown in Table five.
The results present that the cuttings recoveries of those three kinds of drilling fluid are each higher than 95% to the Nahr Umr Shale; even though the swelling ratios are distinctive. These benefits display that the inhibitive capability in the drilling fluid is great ; alternatively, the outcomes indicate that the formation hydration is feeble. The inhibitive capacity of the drilling fluid is not really the primary motive for the wellbore instability in the Nahr Umr Shale.