Characterization Geochemical Gas While Drilling Impacted Determination Porosity-Applied in Deltaic Sedimentation Multilayer Hydrocarbon

Uncertainty in interpretation of the existence and characteristics of each reservoir layer will greatly influence the level of success in the drilling process. Formation evaluation through wireline logging operation can obtain information about reservoir characteristics, one of which is calculating rock porosity, is sometimes not carried out due to limitations in drilling operations which are closely related to drilling costs which are increasingly expensive. The Semberah Field is located in a delta depositional environment which has reservoir layers that have been producing since the 1970s. Drilling activities that produce data in the form of gas drilling ratio and wireline logging have been widely carried out but still have problems in analyzing rock porosity values. To improve level confidence and limitation data affected drilling operation during attempt porosity analysis thorough wireline logging, gas drilling ratio data from 10 wells was taken and then several gas chromatography ratios were calculated, namely wetness, balance, and fluid mobility or estimated potential porosity (FMPP). Then, all these ratios were compared with the effective porosity (phie) from the petrophysical calculation. FMPP apparently has a sensitivity value that matches the phie value from Petrophysical calculations, namely around 70.25%. This gas drilling ratio method is expected to reduce the uncertainty of porosity calculations due to geological environment and in the future can be used as data to determine reservoir characteristics without having to use expensive wireline logging data.