Expectation for the presence of hydrocarbon seepage in onshore tropical region, case study in Miri Sarawak Malaysia

Abstract

Long term course of hydrocarbon seepage on material sediment and water alters mineralogical composition with corresponding change in chemical and physical properties of rocks and soils. This changes color, hardness, electric, magnetic and radioactive properties of minerals. This alteration product occurs at the surface coincide with the original product of seepage, namely gas emanation, crude oil and brine water effluent resulting change in fertilities rank soils and vegetation manifest which indicated with vegetation stress and bare development. This leads to change refection, absorption accompany with change in albedo, change in surface thermodynamic and emission properties accompany with change in land surface temperature (LST). District of Miri, Serawak state of Malaysia is used for study area. This area is an urban area, located in the tropical region with the complex land cover system around the city. It is potentially having some hydrocarbon seepage due to existing petroleum system. Topographic map of Miri was used to make boundary of internal and external seepage potential area, and LANDSAT ETM+ was used to derivate of albedo and day time land surface temperature. The objective of study is to detect hydrocarbon seepage in onshore area through the investigation of land use / cover anomaly on surface albedo and land surface temperature. Intensive land use / cover classification and corresponding comparison of statistical analysis were performed on albedo, land surface temperature between internal and external seepage potential area. Two dimensional cross plots was also applied to obtain the probable location of seepage. The result clearly shows that the presence of hydrocarbon shifted albedo and LST. The shift was vary with different land use / cover class. The shift was relevant with the resulted pattern of two dimensional cross plots. The cross plots pattern was also shows the probable location of hydrocarbon infected area. According to shift direction, two dimensional cross plots pattern, and employing statistical mean value of albedo and LST in internal seepage potential area for each class allows to expecting the region for the presence of hydrocarbon seepage.