A Preliminary Study on Sedimentary Mode of Putaohua Oil Layer in the East of Sanzhao Depression

Abstract

Based on ten well cores, seventeen hundred logging data and initial potential data, sedimentary characteristics and mode of shallow lacustrine fluvial-dominated delta of Putaohua oil layer in the east of Sanzhao depression were analyzed. It is realized that distributary channel sandbodies as sand body framework of this delta system, which is abundant, closely and narrow, and the framework of sand body is in a large number of narrow banded shape (mostly 200 ~ 300m), and can extend hundreds of kilometers of continuous, dense, overall was SW, and combines well with other types sand surface to become a better distributary channel sand body. Based on understanding of sedimentary background, developmental process, sedimentary characteristics and sedimentary facies type of Putaohua oil layer in Sanzhao depression, sedimentary mode of shallow lacustrine fluvial-dominated delta is established in the study area, and sedimentary mode of five subfacies is further divided: Delta distributary plain subfacies is mode of fluvial-dominated belt body; Transition region of front-distributary plain is mode of inshore; Inner front is mode of fluvial-dominated belt body; Transition region of inner front-outer front is mode of fluvial-dominated sheet sand; Shallow lacustrine fluvial-dominated delta outer front is mode of tide-dominated sheet sand; Also pointed out that overall shows NE –SW trending submerged distributary channel sandbodies which is abundant, closely and narrow is the main reservoir of the study area. It provides the solid geological basis for the establishment of spatial distribution pattern of reservoir; identify the causes of mainly monosandbody and further tapping the potential of oil field.