An approach to Design of a Water-based Drilling Fluid in Shale Formations (Case study:Khangiran Oilfields in Iran)

Optimum design of a drilling fluid plays a crucial role in a drilling operation. Oil-based drilling fluids are extensively used in shale formationswhere such drilling fluids can affect the environment. Thus, notable attempts are being made to design a drilling fluid with lowest impacts on the environment; the approach to water-based drilling fluid design in shale formations. The aim of this research study is to design an environmentally friendly water-based drilling fluid which can be utilized in drilling of water sensitive formations. With this regard, a database including history of drilling operations as well as characteristics of shale formations in Iranian oil fields, Khangiran oilfields, is primarily established. Using newadditives consist of new polymers, shale inhibitors and sized solid particles, an optimum water-based drilling fluid is then designed which has the properties such as clay mineral alteration and activity reduction, reduction in formation damage, stability in acidity changes, stability at high temperatures, improvement of the integrity of drilling cuttings, better controlling the mud filtrate and pressure invasion to the formation, and the compatibility with drilling fluids dilution during drilling operation. Compared to other similar water-based drilling fluids, the lubricity and shale cuttings recovery of the proposed drilling fluid are improved. Application of this water-based drilling fluid could lead to effective protection of the environment and employees as well as economic advantages.

Keywords:

Drilling , Shale formation , Water-based drilling fluid , Polymer , Environmentally friendly , Khangiran oilfields