TITLE:
Research on High Density Oil-Based Drilling Fluid and Application in the Southern Edge of Junggar Basin, China
AUTHORS:
Yidi Wang, Yuezhi Wang, Biao Ran, Pengyun Xing, Xiaoliang Xin, Yi Li
KEYWORDS:
Junggar Basin, Southern Edge, High Steep Structure, High Density Oil-Based Drilling Fluid System
JOURNAL NAME:
Open Journal of Yangtze Oil and Gas,
Vol.3 No.4,
October
26,
2018
ABSTRACT: The southern edge of the Junggar basin has broad exploration potential. However, high-frequency complex drilling accidents in this area lead to the reduction of the average drilling speed and the extension of the drilling cycle. The main geological reason is that this area was affected by the process and developed high and steep geological structure. The nappe formation with a large dip angle and poor stability developed along faults. The major rock type of this E2-3a formation is mud-stone which has strong water sensitivity and can be hydrated and dispersed easily, which leads to the wellbore shrinkage and the borehole collapse. In order to improve the drilling speed in the southern edge of the Junggar basin and accelerate the exploration and development process, the drilling fluids associated with drilling problems in this area were investigated in this paper by combing the geological information and historical drilling records. Because of the special characteristics of this formation, it is concluded that the water-based drilling fluids previously used in this area are not suitable to solve the complex drilling conditions; a high density oil-based drilling fluid system has been developed for this area by conducting studies in the laboratory initially and being tested in the field later. In addition, its rheology, stability and pollution resistance performances were evaluated. Results show that, the rheology, the stability and pollution resistance capacities of the drilling fluid satisfy the drilling requirements. The fluid was applied in well H101 and the results show that the ROP of section 311.1 mm of the well was increased by 763% compared to the wells drilled in the same area and the total drilling time of well H101 was reduced by more than 80%, which was a historic breakthrough of the drilling speed in the southern edge.