Layered model as a Sample Clauses

Layered model as a priori information In this case, the analytical SFT profile derived from the initially given profile (Eq. 1) was not taken as a prior SFT model for the 0 – 2500 m depth interval. Instead, the SFT model from surface to 3350 m was assumed to be composed of several 500-m thick layers. The temperature values measured within each layer were used to compute the most probable average temperature and gradient in the corresponding depth interval. Hence, using Eq. 3, the best SFT profile was estimated layer after layer starting from the wellhead and applying recursively the temperature obtained at the bottom of a layer as fixed temperature for the top of the next layer. This procedure prevents propagation of too much artifacts in the logging data from one depth to another and should mitigate effects mentioned above. It was applied to L10a and the results are shown Figure 16. As observed, the estimated SFT is once again larger than the initial given estimation for the first 2500 m depth interval. The major convection zone still starts around 500 m depth. The varying injection flow rate at the beginning of the logging, however, still influences the SFT down to 1500 m depth, and especially the unrealistically low SFT value at 1500 m. From 2000 m, the SFT profile exhibits more realistic values again. At 2500 m, the SFT is estimated to 354°C, which is 29°C warmer than the previous estimate. Such a difference comes from the different a priori inversion methods. In the first case (Subsection 3.4.2), the SFT profile was assumed to have the exponential form of Eq. 1 and the data for the whole depth interval were used at once to find the best fit. According to Eq. 1, the temperature must remain constant in the convection zone and temperature at 2500 m is strongly linked to temperatures above the convection zone. Here, on the contrary, only data from 500 m depth intervals are constraining the fit, gradually. Below 2500 m, the SFT increases slowly to reach 398°C at 3350 m. Figure 16: (Left) SFT profile until 3350 m obtained around well RN-15/IDDP-2 for a 500-m layered model using WellboreKIT and L10a (red line), overlaid with the initial profile (black line). (Right) Observed (black line) and simulated (red circles) fluid temperature associated with L10a.