Comparison of Porosity in Carbonate Petroleum Reservoir Rocks of Bombay Offshore

In carbonate rocks porosity is of varied origin, subsequently modified, destructively or constructively by several stages of diagenesis. The ultimate porosity of a carbonate reservoir rock is an algebraic sum of all these processes. As a result, porosity in carbonate rocks varies over very short distances both horizontally and vertically. A partial solution to this problem of evaluating porosity variations may be had by generating and comparing frequency distributions of porosity over neighbouring wells. The method is illustrated by comparing porosities of two wells from Bombay offshore area by the simple non-parametric Kolmogrov-Smirnov distance or 'D' statistic. By this method it is shown that Bassein 3 and South Bassein well No.1 are significantly different; further, it is shown that South Bassein well No.1 has a better porosity development than Bassein well No.3. Kolmogrov-Smirnov' D' statistic is an universal one and must find favour among Petroleum Engineers and Reservoir Geologists.