# A New Algorithm Model Based on Extended Kalman Filter for Predicting Inter-Well Connectivity
## 6 Quantitative Classification of Ineffective Circulation Channels
### Application of Ineffective Circulation Channels
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Block**} & \multicolumn{3}{c}{**Well ID**} & \multicolumn{3}{c}{**Development Parameters of Ineffective Circulation Channel**} & \multicolumn{3}{c}{**Connectivity Coefficient**} & \multicolumn{3}{c}{**Distribution Coefficient**} & \multicolumn{3}{c}{**Connectivity Volume (\(\mathbf{m}^{3}\))**} \\ \cline{2-13}  & **Injection Well** & **Production Well** & **Level** & **Mid** & **Current** & **Early** & **Mid** & **Current** & **Early** & **Mid** & **Current** \\ \hline \multirow{4}{*}{South Block Nml3} & C03 & H03H & June 2017 & 0.21 & 0.63 & 0.68 & 0.14 & 0.44 & 0.55 & 124/067 & 249/348 & 293/610 \\  & B26 HS & May 2018 & 0.20 & 0.81 & 0.83 & 0.11 & 0.46 & 0.60 & 227/385 & 48/8990 & 548/067 \\  & B27H & March 2015 & 0.77 & 0.56 & 0.89 & 0.35 & 0.31 & 0.57 & 473/516 & 336/144 & 573/306 \\  & C25 & H11H & August 2018 & 0.49 & 0.58 & 0.73 & 0.27 & 0.37 & 0.53 & 190/479 & 302/135 & 483/655 \\  & H14H & January 2015 & 1.62 & 0.29 & 0.73 & 0.61 & 0.11 & 0.28 & 309/358 & 58/654 & 236/323 \\  & C31 & H2H & January 2015 & 1.17 & 1.25 & 0.78 & 0.37 & 0.39 & 0.44 & 240/949 & 650/40 & 290/450 \\  & B12 & B11 & November 2017 & 0.72 & 0.82 & 1.21 & 0.26 & 0.30 & 0.44 & 71,276 & 79/329 & 119/762 \\  & B22 & B21 & December 2021 & 1.23 & 2.16 & 1.76 & 0.24 & 0.42 & 0.34 & 471/031 & 116/2740 & 558/428 \\  & B17 & August 2016 & 0.22 & 0.83 & 1.32 & 0.093 & 0.35 & 0.56 & 36,503 & 192/496 & 221/955 \\  & B16 & B21 & August 2016 & 0.49 & 1.34 & 2.03 & 0.127 & 0.347 & 0.526 & 138/368 & 405/413 & 644/107 \\  & B11 & April 2016 & 0.15 & 1.35 & 2.01 & 0.043 & 0.385 & 0.573 & 11,156 & 64,637 & 145/147 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Statistics of typical well groups in Quhuangdao 32-6 oilfield. The decrease-increase-decrease pattern has been witnessed in wells C31-H02H and B21-B15. The connectivity volume and coefficient first decrease, then increase, and finally decrease. Such patterns may reflect changes in the dominant water flow path, indicating periodic development of ineffective circulation channels. Compared with the first two patterns, the connectivity changes in this pattern are more complex. For such complex periodic changes, it is recommended to optimize the injection rate during the phases of decreasing connectivity to maintain a stable inter-well connection. Phase-wise adjustments to both injection pressure and production rate can help maintain balanced pressure between well groups, reducing the further development of ineffective circulation channels. Regular evaluations of inter-well connectivity are also advised to assess the effectiveness of injection and production adjustments. In summary, the proposed SV-DC model associated with the recommended grading formula can be used to analyze the dynamic changes in inter-well connectivity parameters, which can identify and understand the evolution law of connectivity volume and connectivity coefficients of different well groups, which is of great significance for optimizing water injection strategy and improving reservoir recovery efficiency. Compared with conventional methods, the SV-DC model provides a more flexible approach to handle the dynamic changes in inter-well connectivity, especially under complex injection and production conditions. Unlike traditional methods that excel in stability and simplicity, the SV-DC model captures the dynamic characteristics of inter-well connectivity with higher time resolution, enabling more detailed analysis across different injection phases. These features make the SV-DC model advantageous in guiding future injection strategies and improving recovery efficiency. The algorithm model for calculating the inter-well connectivity coefficient and the quantitative evaluation methods for ineffective circulation channels can be easily programmed into the oil reservoir development information system platform to serve field operators.