Author(s)

Huiying Zhai, Baolin Liu, Zhen Nie, Qizhi Huang and Min Feng

Corresponding Author

Huiying Zhai

ABSTRACT

The lithology of the 3/7 oilfield in South Sudan is dominated by claystone and sandstone, during the drilling operation, the formation loss, tight hole and caving of the wellbore are prone to occur. This paper analyzes the formation lithology in this area, and summarizes four kinds of drilling problems such as formation loss, tight hole and collapse, bit balled up and stuck. Reasonable and effective treatment methods and preventive measures are proposed according to different drilling troubles, including leakage plugging technology while drilling, cement plugging technology, a progressive method from easy to difficult to solve the stuck, and so on. The drilling troubles technical countermeasures proposed in this paper provide an important technical reference for high efficient drilling in other similar blocks, and will help to reduce the non-production time, lower the drilling cost in the 3/7 area of South Sudan.

KEYWORDS

Drilling troubles, loss, tight hole and caving, balled up, stuck