Porosity measurement and petrophysical properties of the Indonesian limestone as reservoir rock by using X-ray and neutron imaging technique

The oil and gas are usually trapped inside the reservoir rock pores such as Limestones or Sandstone. Most of the oil and gas companies use the common method for calculating rock total porosity by using Helium (He) or Nitrogen (Ni) gas. But this technique is limited only in total porosity information of the limestone, not the petrophysical properties of the sample. Another powerful technique that can be used to investigate the internal structure of the rock is Neutron Imaging (NI). Several experiments related to NI about porous rocks have been done by another researcher, but an experiment about the reservoir rock properties with NI has not been done. Porosities are one of the most important parameters to predict the availability of oil or gas. X-Ray Imaging (XRI) was describing perfectly these porosities, but again the XRI only provide porosities information of the limestone. To surpassing this limit, NI was employed. NI does not limit only to visualize the rock porosity but also can distinguish inhomogeneities materials inside the limestone. In this paper, the Limestone sample has been investigated by employing tomography methods of both XRI and NI technique. The total porosity from both technique then compared by the java petroleum systems databased (conventional method). From the experiment knew that the total porosity of the Limestone was about 28.4%, 34.36%, and 30% - 36% by an XRI, NI and conventional method respectively. XRI detected all porosity including a traped pores, channel pores / interparticle, Intercrystalline and Vugular pores. It was known that there were a lot of channel pores inside the sample which made the oil flow in the centre of the stone while the crude oil extracted by the oil company. On the other hand, NI gives more information about inhomogenous minerals inside the Limestone belongs to Dolomite, Aragonite, Calcite, Magnesite, Ankerite, and Siderite.