OS PAYSAL SYSTEM - Reservoir Drill-in Fluid System
Product Information / Description
OS PAYSAL SYSTEM comprises of specially ground and sized, pure Sodium Chloride salt as the main bridging agent, together with optimised levels of water based polymers to provide viscosity (particle suspension) and tight fluid loss control. The viscosifier is high quality Xanthan Gum and the fluid loss polymer is a specially modified polysaccharide intended purely for use in monovalent saturated brines.
OS PAYSAL SYSTEM is primarily intended to be used as a non-damaging mud for drilling the completion sections in sandstone reservoirs comprising consolidated, unconsolidated sands and even where there are inter bedded reactive shales and clays. It can, used correctly, also be used to drill reservoir sections in highly fractured carbonate reservoirs where acid soluble carbonate muds are undesirable.
The most basic formulation, with minimum solids loading of approximately 50ppb, will seal up to 10,000 millidarcies (mD) during drilling but can be easily removed without acid during the completion phase, as the components are essentially water soluble.
The fluid can be modified so that it can be used as a post-completion pill during the installation of the completion assembly. This usually is done by adding the larger OS PAYSAL BLOC products so that a temporary internal seal can be placed on the inside of sand exclusion screens. This pill can be removed with water or by simply bringing on the well as the lift-off pressures are relatively low.
OS PAYSAL SYSTEM is normally made using saturated NaCl brine(1.2sg/10.00ppg ),thus maintaining the concentration and size of the ground sized salt particles essential for primary bridging during drilling. It can also me made using other monovalent saturated brines most commonly saturated NaBr brine (1.5SG/12.5ppg) – these saturated brines can also be mixed to give varying density saturated brine starting points – in this way the solids level of the mud can be minimised.
Hundreds of wells have been successfully drilled and completed worldwide using this system.