\begin{table}[ht]
\centering
%\footnotesize
%\tabcolsep
%\arraycolsep
%\node (table) [inner sep=0pt]{
%\footnotesize
\caption{Potential of nanotechnology applications in petroleum industry}
\renewcommand{\arraystretch}{2}
\begin{tabular}{p{0.7\textwidth}|p{0.2\textwidth}|p{0.2\textwidth}|p{0.2\textwidth}|p{0.2\textwidth}}
%\textbf{\hline Objective & Area}\\
\hline \bfseries Objective & \bfseries Area \\
\hline Improved success ratio of exploration by improving data gathering, recognizing shallow hazards and avoiding dry holes.& Exploration \\
\hline Improved performance and reliability in drilling, tubular goods and rotating parts by improving the strength and endurance of the material pH (4-5\% in dispersion) & Drilling \\
\hline Production assurance in diagnostics, monitoring surveillance and management strategies&Production \\
\hline Corrosion management for surface and subsurface & Production \\
\hline Corrosion management for surface and subsurface & Facilities \\
\hline Refining and petrochemical technologies& Downstream \\
\hline Enhanced oil and gas recovery through reservoir property modification, gas and water injection modification. & Reservoir \\
\hline
\label{potofnan}
\end{tabular}
\end{table}
I have issues to contain that table in the A4 page. Someone can fix it for me?

tabularenvironment would appear to contain only two columns, yet the header sets up five columns -- are the last three needed? – Mico Jun 03 '15 at 18:27