| abstract |
The invention describes a water-based drilling fluid containing a polymer latex capable of forming a deformable latex film, at least in a portion of the formation (downhole section), which allows filtering of pressurized drilling fluid when drilling wells for gas or oil in clay shale Preferably, a precipitating agent is used in conjunction with the polymer, for example, a silicate or an aluminum complex (for example, sodium aluminate). Water present in the drilling fluid usually contains salt, forming a brine, often saturated, although the invention is also feasible with the use of fresh water. When using salt, it is often advisable to additionally use a surfactant, such as betaine. |