Miocene Chemical Stratigraphic Correlation of Exploration Wells from Pearl River Mouth Basin, South China Sea

CHEN, XIDONG, DOUGLAS WILLIAMS, and NANCY HEALY-WILLIAMS, University of South Carolina, Columbia, SC, and J. WANG, NHEOC, Guangzhou, China

The South China Sea (SCS) and its margins constitute a frontier area in the global search for hydrocarbons. One of the most important areas of the SCS is the Pearl River Mouth (PRM) basin, which seismic stratigraphy indicates contains up to 10,000 m of Cenozoic sediments. Oil exploration in the PRM basin provides numerous exploration wells to study. In many cases, standard biostratigraphy often lacks the resolution and accuracy necessary for hydrocarbon exploration and production due to the complicated nature of sedimentation in the PRM basin. We are applying chemical stratigraphy to achieve an alternative, higher resolution stratigraphy in the PRM. Stable isotope analysis has been performed on Miocene reef carbonate sections in five exploration wells of the PRM basin. Our results ind cate that such geochemical measurements represent a potentially powerful tool for providing high resolution stratigraphic correlation of Neogene exploration sections of the South China Sea. Isotope data from whole rock analyses show that O(18) values range from -2.9 to -6.5% (PDB) and C(13) values range from -7.1-4.9% (PDB). The O(18) and C(13) records provide a preliminary high resolution stratigraphic zonation defined by three intervals: A, B, and C. Intervals A and C have similar isotopic signatures for both oxygen and carbon. However, the O(18) values for interval B are 1-2% (PDB) more negative than interval A and C, and the C(13) values of B are as much as 6-8%(PDB) more negative than A and C. Cross-correlation analysis of the isotopic signatures indicates that the O(18) and C(13) s gnals of these wells have very high cross-correlation coefficient values averaging 0.65 at zero lag, even though the lithological characteristics are quite different for each well. These results imply that the isotopic signals are independent of the lithological properties of the PRM wells.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)