Polyglycol provides superior shale inhibition property and wellbore stabilization due to chemical adsorption and unique chemistry of poly glycols.
Chemical adsorption though applicable both below and above cloud point, is greater when glycol has clouded out and is in colloidal form, thus resulted in glycol-coated clays that are somewhat water repellant.
As the temperature cools, the glycol becomes more water-soluble and a grater portion of inhibitor is retained in the drilling fluid.
The inhibition mechanism can be readily combined with more traditional cation exchange and encapsulating mechanisms to provide the excellent inhibition characteristics of the polyglycol drilling fluid system.
Shale inhibition is improved when the polyglycol is insoluble or ‘clouded out’ state when it provides a barrier against water migration into the shale while it plugs shale pores to prevent the equalization of hydrostatic pressure away from the well bore.
‘Cloud point’ is the temperature where poyglycol additives change from being soluble (at lower temperatures) to being insoluble (at higher temperatures). The cloud point temperature can be reduced by increasing the salinity (or other electrolytes) or by increasing the concentration of polyglycol.
The improved shale inhibition of polyglycol leads to lower dilution volume, fewer hole washouts and reduced instances of stuck pipe, which translate into less waste volumes requiring disposal and more pollution prevention and source reduction opportunities. Using the polyglycol system, at temperature above its cloud point, through a producing reservoir will significantly reduce invasion into the reservoir, and no glycol will be present in the filtrate. This gives rise to extremely low skin factors and, coupled with an easily removable filter cake, makes the polyglycol system applicable for non-cemented completions.
By engineering the system so the polyglycol cloud point matches the downhole temperature, maximum benefit can be obtained. Above this temperature, the glycol forms a type of micro-emulsion which is often referred to as a “Thermally Activated Mud Emulsion” (TAME).This TAME effect contributes to stabilizing the wellbore in three distinct ways:
Micro-emulsion and precipitate pore plugging
Filter cake improvement.
CRISTOL-CPG 208 is a low toxic, versatile, medium cloud point additive designed for medium- to- high salinity water level system and can be used in wells with moderate formation temperature. It can provide improved well bore stability, lubricity, high temperature filtration control, plus reduce dilution rates and bit balling. In a non-dispersed polymer system is most effective when used in conjunction with inhibitive salts like KCL.
Typical Physical Properties
Appearance : Yellow to amber liquid
Specific Gravity @ 20° C : 1.015 – 1.035
pH – 5% aqueous solution in DM water : 6 – 8
Cloud point – 3% in 15% NaCl solution : more than 65°C
Improved wellbore stability and shale inhibition.
Improved high temperature filtration control.
Reduced dilution rates and mud consumption.
Reduced bit balling potential.
As an insoluble liquid it causes slight increases in plastic viscosity.
For offshore operations CRISTOL-CPG 208 display relatively low marine toxicity, provides relatively fast biodegradation rates, minimizes cutting piles.
For onshore it can be engineered to provide shale inhibition with out the use of salts and Contain no aromatic or cyclic hydrocarbon compounds, making cuttings ideally suited for land farming.
Toxicity and Handling
Handle as an industrial chemical, wearing personal protective equipment and observing the precautions as described in the Material Safety Data Sheet (MSDS).
Packaging and Storage
Store in dry, Well-ventilated area. Keep away from heat, direct sunlight, sparks and flames.
Follow safe ware-housing practices regarding palletizing, banding, shrink-wrapping or stacking.
* Specifications are subject to change depending upon client specification.*