Key technologies of lithologic trap exploration in marine delta of Enping Sag in Pearl River Mouth Basin

WU Jing;DING Lin;ZHANG Xiaozhao;WANG Fei;GONG Wen;LI Xiao;Shenzhen Branch,CNOOC;

Enping Sag;;lithologic trap;;interpretive treatment;;sedimentary microfacies;;quantitative characterization;;marine delta

Through the research on the hydrocarbon accumulation conditions of Enping Sag, a hydrocarbon-rich sag, some new types of lithologic traps in the Pearl River Mouth Basin may have been discovered: interchannel bay mud type, delta lobe type and isolated sand dam type.In order to study the lithologic traps in Enping Sag of Pearl River Mouth Basin, the evaluation system of marine delta lithologic traps in Enping Sag of Pearl River Mouth Basin wasestablished, and a series of key technologies were formed, including seismic interpretation processing technology(frequency division technology based on wavelet transform and frequency extension technology based on well-controlled spectrum shaping), high-resolution sequence analysis technology, high-precision sedimentary evolution analysis technology and quantitative characterization technology of favorable sand bodies(three-dimensional forward simulation technology, multi-attribute analysis technology, phase-controlled frequency division inversion technology), with a view to providing technical support for lithologic trap exploration in Enping Sag.The lithologic traps of Neogene marine delta in Enping Sag of Pearl River Mouth Basin were studied by using the above four key techniques.It is found that two favorablelithologic traps are mainly developed in Enping 24 fault structure belt and Enping 15 buried hill covered structure belt.Enping 24 fault anticlinal structure belt is dominated by underwater distributary channel in high level area, and Enping 15 buried hill covered structure belt is dominated by underwater distributary channel at the end of high level area and delta front sand body in transgression area.According to the results of the study, the first lithologic trapexploration well B1 in Enping 15 buried hill covered structure belt is successfully drilled, which proves the potential of lithologic traps in Enping Sag and the effectiveness of lithologic trap exploration technology in Neogene marine delta in Enping Sag, Pearl River Mouth Basin.It also provides a more accurate technical basis for determining the target oflithologic traps in the study area.