Advances in Structural Understanding in Northern Sarulla, North Sumatra, Indonesia from Analysis of Lidar Images

Abstract

Exploration and structural mapping at Sarulla in the 1990s was difficult due to the thick forest cover, steep terrain, and limited resolution of remote sensing techniques. When Lidar images were obtained in 2015, many new faults were identified and mapped, and a major sector collapse became visible at Namora-I-Langit. Here we present the results of this work, which has been updated through recent review and further structural analysis. The Sumatra Fault Zone (SFZ) was seen to comprise major faults that strike between N-S and NNW-SSE, with complex horsetails and sinuous linking faults between the major structures. The SFZ is cut by cross faults that are almost perpendicular to it, and an older set of ENE-WSW faults is also visible. The sector collapse at Namora-I-Langit has exposed the clay cap over an area that is up to 2 km wide by 5 km long, and this area hosts over 90% of the thermal features. In forested terrain like Sarulla, Lidar images are a very quick, cost effective and accurate way of analysing geomorphology and structural features. In such areas, having Lidar images available at an early stage should be considered as essential as MT geophysical surveys prior to siting wellpads and targeting wells.