TITLE:
High-Inclination Coring of Chang-63 of the Yanchang Formation in Huaqing Oilfield, Ordos Basin: Implications for Ancient Flow Direction and Fracture Orientation
AUTHORS:
Kun Chen, Xuefeng Qü, Qichao Xie, Jian Liu, Jiwei Wang, Youan He, Dong Sun, Yexiong Peng
KEYWORDS:
Core Orientation, Tight Sandstone Reservoirs, Sandy Debris Flow
JOURNAL NAME:
Engineering,
Vol.15 No.1,
January
31,
2023
ABSTRACT: A
promising method is to use coring of high-inclination well to find ancient flow
direction and orient tiny natural fractures in massive sandstone of sandy
debris flow. Determination of ancient flow direction can reduce the number of
exploration wells, and orientation of natural fractures is of guiding significance to the deployment of water injection
development well pattern. In Block X of Huaqing Oilfield, Ordos Basin,
the cores of Chang 63 section were obtained from Well Y through 16 coring operations, with a total length of
105 m. Cores is oriented through drilling parameters, the number of cores, the angle between the core edge and horizontal bedding, the coincidence degree of
core profile and directional flame structure. Therefore, the micro-fractures on
the core are directional. The ancient flow
directions of sandy debris flow were restored by load casting, groove casting, groove
casting and imbricate structure. Our results show that the ancient flow
directions of sandy debris flows were southwest, southeast, northwest, and west
from bottom to top. The front of the Wuqi Delta is the main source of blocky
sandstone with the best oil-bearing property. Affected by the topography of the lake
bottom, the sandy debris flow turned locally in the northeast direction, and
the sandy debris flow from this direction was formed. The NEE-SWW-trending
fractures formed in the Yanshanian period are most developed in the Huaqing
area, which should be considered in deploying the flooding well network. The
north-south micro-fractures formed in the Himalayan period can improve the
physical properties of tight sandstone, which is of great significance for
tight sandstone reservoirs.