Investigation of trend between porosity and drilling parameters in one of the Iranian undeveloped major gas fields

Porosity is one of the main parameters that should be considered when a gas or an oil field is assessed. Hence, the availability of porosity is crucial in any rock and formation analysis. However, this parameter is not always available and direct measurement is scarce and usually is confined to appraisal phase of a field. Therefore, in this study it is aimed to find a relationship in order to estimate porosity in afterward phases. The data of 5 appraisal wells of an undeveloped gas field has been gathered to perform this purpose. The full set wireline logging data and drilling data were available. ‏The data inherit high level of fluctuation which is normal with respect to real direct measured data. The smoothed curving was utilized and as a result, the fluctuation was diminished considerably and the feasibility of carrying out the investigation was being established, accordingly. To normalize and gather drilling data in a parameter in order to have a better view and investigation, sigmalog method was employed. It was observed that there is a clear exponential relationship between porosity and drilling data and curve fitting was utilized to conduct a numerical relationship. The curve fitting was established with R² = 0.83 and a trustworthy fitting resulted. The results demonstrate the possibility of porosity estimation by using drilling data. Furthermore, a numerical relationship is given for a specific field. The porosity estimation can lead to better analysis of newly drilled rocks and formations leading to more efficient field development strategies.