Assignment

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3 Buckley-Leverett analysis. (i) Buckley–Leverett analysis quntify sweep efficiency or local displacement efficiency? Explain your answer while defining both these terms. Sweep efficiency 𝑬𝒔: is what fraction of the reservoir volume is contacted by water and is controlled by variation of absolute permeability and well. Local displacementis efficiency 𝑬𝒅: is how much oil is recovered from a region of rock contacted by water and is controlled by the relative permeability. Buckley-Leverett analysis analysis studies water injection into a reservoir containing some initial water saturation, so it quantifies local displacement efficiency. (ii) Explain how you can use the results of Buckley -Leverett analysis combined with field production data to estimate sw eep efficiency. Use a diagram to explain your reasoning and list what other information is needed. Since the real reservoir is heterogeneous, the recovery will always lie below that from an idealized Buckley -Leverett analysis, but does serve as very useful basis of comparison. The closer the real recovery is to Buckley-Leverett analysis, the better the injection wells are contacting and sweeping the reservoir. It also serve sas guide to how much water needs to be injected to achive optimal recovery. (iii) Plot the relative permeability curves shown below, as well as the corresponding fractional flow. 𝐾𝑟,𝑤 = 5 ∗ (𝑆𝑤 − 0,25)3 𝐾𝑟,𝑜 = 3 ∗ (𝑆𝑜 − 0,2)2 𝜇𝑜 = 0,002 𝑃𝑎. 𝑠 ; 𝜇𝑤 = 0,001 𝑃𝑎. 𝑠 𝐾𝑟,𝑜 = 3 ∗ (𝑆𝑜 − 0,2)2 = 3 ∗ (1 − 𝑆𝑤 − 0,2)2 = 3 ∗ (0,8 − 𝑆𝑤)2 Now we need to search the values of 𝑆𝑤𝑖 and 𝑆𝑜𝑟, that are the values for which 𝐾𝑟,𝑣 = 0 ; 𝐾𝑟,𝑜 = 0 . 𝑆𝑤,𝑖 = 0,25 ; 𝑆𝑜,𝑟 = 0,2 ; 𝑆𝑤,𝑓 = 0,8 In order to plot the relative permeability graph we have t o finde several point which have 𝑆𝑤 in the range between 0,25 and 0,8 , let’s use a…