Publications

Onshore reflection seismic surveying for shallow objectives is a challenging task in Indonesia. Shallow seismic survey are often face with very stringent demands on spatial resolution and time/cost consumption. Economic and enviromental reasons dictate the use of surface seismic source. The use of explosive seismic source, such as dynamite, become inefficient, time/cost comsuming and not eco-friendly. We propose to use AWD (accelerated weight drop) as seismic source for this eco-friendly onshore shallow seismic survey. This kind of seismic source was chosen because of its easiness during the operation in the field, low cost and having high frequency content in the reflection data. The experiment was conducted around Jepon-1 well in Blora District, Central Java, Indonesia which is a candidate for CO2-injection. This experiment was carried out in August and November 2015 as initial investigation before baseline seismic survey is carried out around mid-2016. The CO2-injection itself will be started end-2017. This site was chosen as the first carbon capture and storage (CCS) pilot project in Southeast Asian region, and funded mostly by international supporters. The target of CO2-storage is Ngrayong sand intervals situated between 800 – 1,100 m below surface. The purpose of this survey is not to map the reservoir target for CO2 injection, but only to study the effectiveness of the AWD source for shallow seismic survey. Moreover, this survey is intended only to test the performance of AWD seismic source and determine the optimum survey parameters for subsequent baseline seismic survey for monitoring CO2 injection in Jepon-1 well and its vicinity. Based on the recorded and processed data, we found out that the deepest reflections that could be imaged is only 650 m below the surface. To complete the data acquisition with a total length of 500 m, it took only two operation days with a total cost of about USD 2,000. , This survey was completed without any damage claims. Thus, from economical point of view, the use of AWD needs much less investment than similar surveys using dynamite or mini vibroseis as seismic source.