Generation, Migration, and Accumulation of Deep Natural Gas in Songliao Basin

GUAN, ZHENGMIAO, Research Institute of Petroleum Exploration and Development, Langfang, China

Through the study of 2109 ft of core from the Block V-Lamar field, central Maracaibo basin, Venezuela the environments of deposition were established. The studied interval corresponds to the informal C2 sands of the Misoa Formation (Eocene). Seven different lithofacies were identified and later grouped into three sedimentary units deposited in a general, fluvial-dominated deltaic environment.

The organization of the different lithofacies along with palynologicai data permitted the assignment of lower delta plain, upper delta plain, and, again, lower delta plain for the sedimentary units. The main subenvironments encountered include amalgamated distributary channel bars and related interdistributary bays. The distributary channels are thicker in the upper delta plain unit owing to a higher degree of stacking. Furthermore, sandstone thickness decreases in a southwest-northwest sense which indicates the direction of regression. This can be documented also with the petrophysical characteristics of the reservoir reflected as a continuous decrease in porosity from 25 to 18%.

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