Seismic Characteristics of Mud Diapir in Song Hong Basin, Offshore Vietnam

Anh Ngoc Le

doi:10.46717/igj.54.2a.1ms-2021-07-22

Abstract

Seismic characteristics of mud diapir has been investigate over an area of 3900 km2, located in the central part of Song Hong basin, using four 2D seismic lines. There are six mud diapirs and three mud pipes have been documented. The core of the diapir is characterized as a zone of chaotic, disrupted seismic reflection, with the amplitude reflection ranging from low the high. High amplitude reflections are distributed in the top of the some diapir, which is possibly related to the gas accumulation. They are in different sizes, shapes, and the relationship with surrounding rock. They are characterized as deep sourced, high energy rooting from Oligocene/early Miocene shale layers. This organic rich shale rocks are in the oil and gas windows, thus their hydrocarbon generation combining with the tectonic inversion during Miocene make the overpressured shale and therefore rising the diaipirs. The area has experienced several phases of eruption in Middle Miocene, Late Miocene, Late Pliocene and Present day. The discovery and identification of the occurrence of mud diapirs implied a great potential for prediction of structural traps in the central part of the Red River Basin.

Highlights

Diapirs are domes created by deformations of mobile sediments; they may deform or disrupt overlying rocks
Each phase is resulted by several control factors i.e., regional tectonics, the differences in density between the mobile sediments and its overburden rock, sedimentation rate, even though these phases originally use for salt diapir evolution, even though, it still can be applied for the mud diapir as they have similar mechanisms. (Morley and Guerin, 1996; Van Rensbergen et al, 1999)
This paper focuses on the characterization of mud diapir structures by detail seismic facies analysis of 2D seismic lines cutting across the central Song Hong Basin (Fig. 1)

Summary

Introduction

Diapirs are domes created by deformations of mobile sediments; they may deform or disrupt overlying rocks. Mud volcanoes can be observed on the crest of the diapirs (Dimitrov, 2002). Each phase is resulted by several control factors i.e., regional tectonics, the differences in density between the mobile sediments and its overburden rock, sedimentation rate, even though these phases originally use for salt diapir evolution, even though, it still can be applied for the mud diapir as they have similar mechanisms. Rapid sedimentation and hydrocarbon generation will cause overpressure in sediment layers, triggering the diapir evolution (Dimitrov, 2002; Milkov, 2000; Talukder et al, 2003); Tectonic processes are considered to be the main driving forces for the development of mud diapirism (Milkov, 2000; Talukder et al, 2007)

Results

Discussion

Conclusion