# Extended-Reach Drilling (ERD)--The Main Problems and Current Achievements
## 2 Problems with ERD  
When drilling an extended-reach well (ERD), various problems can occur, such as high torque and drag values, inadequate hole cleaning, maintaining a smooth wellbore in a challenging well design, differential sticking, steering during stick/slip, bottom hole assembly design, hydraulics and ECD management [35; 36; 37; 38; 39; 40]. Issues when drilling an extended-reach well are most often related to poor hole cleaning and high values of torque and drag. This represents a huge problem when drilling an extended-reach well, which is especially pronounced in the deviated and horizontal section of the well as far as torque and drag values are concerned, which can cause limitations in reaching desired depths. Another important issue appears with inappropriate hole cleaning, especially in the deviated and long horizontal sections of the well. Table 1 shows examples of extended-reach wells and the issues that occurred in the well, as well as the solution implemented and obtained results. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Source** & **Well** & **Field** & **Location** & **Mud Type** & **TVD (m)** & **MD (m)** & **Problem** & **Solution** & **Results** \\ \hline \multirow{4}{*}{[PERSON] et al., 1999.} & \multirow{4}{*}{-} & \multirow{4}{*}{Niakuk} & \multirow{4}{*}{ Alaska} & Low-solids & \multirow{4}{*}{2700–3000} & \multirow{4}{*}{-} & \multirow{4}{*}{Casing Rotation, centralizers, lubricating agents} & \multirow{4}{*}{Prevent} \\  & & & & non-dispersed WDM, & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\ \cline{2-10}  & \multirow{2}{*}{Gyda A21} & \multirow{2}{*}{Gyda} & \multirow{2}{*}{Ol-based mud} & \multirow{2}{*}{3600–4300} & \multirow{2}{*}{-} & \multirow{2}{*}{running issues} & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \cline{2-10}  & \multirow{2}{*}{Gyda A21} & \multirow{2}{*}{Gyda} & \multirow{2}{*}{Ol-based mud} & \multirow{2}{*}{3600–4300} & \multirow{2}{*}{-} & \multirow{2}{*}{running issues} & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\  & & & & & & & & \\ \hline \multirow{4}{*}{[PERSON] et al., 2000.} & \multirow{4}{*}{M-site} & \multirow{4}{*}{Whych Farm} & \multirow{4}{*}{-} & \multirow{4}{*}{-} & \multirow{4}{*}{-} & \multirow{4}{*}{11,278} & Installing liner to depth & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } \\  & & & & & & & & \\  & & & & & & & & \\ \cline{2-10}  & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{Abu Dhabi} & \multirow{2}{*}{Ol-based mud} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{-} & \multirow{2}{*}{\begin{tabular}{} \end{tabular} } & & & & \\  & & & & & & & & & \\  & & & & & & & & & \\ \hline \multirow{4}{*}{[PERSON] et al., 2005.} & \multirow{4}{*}{-} & \multirow{4}{*}{Hibernia} & \multirow{4}{*}{Canada} & An advanced & \multirow{4}{*}{9360–27} & Hole cleaning, directional and strong wall have to & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } & \multirow{4}{*}{\begin{tabular}{} \end{tabular} } \\  & & & & & & & & \\  & & & & & & & & \\ \cline{2-10}  & \multirow{2}{*}{\
\begin{tabular}{} \end{tabular} } & & & & & & & & \\ \cline{2-10}  & \multirow{2}{*}{
\begin{tabular}{} \end{tabular} } & & & & & & & & \\ \cline{2-10}  & & & & & & & & & \\ \end{tabular}
\end{table} 
Table 1: Problems and solutions in extended-reach drilling.