What is partially hydrolyzed polyacrylamide (PHPA)?

Partially hydrolyzed polyacrylamide (PHPA) is a widely used polymer in the oil and gas industry due to its lesser cost and good water solubility. PHPA is used as a functional additive in water-based drilling fluids. The PHPA mud system stabilizes shale formations and influences cuttings and wellbore stability.

What is PHPA mud system?

SPE Drill Eng 7 (03): 191–199. Mud systems with partially hydrolyzed polyacrylamide polymer (PHPA) are used worldwide and have proved effective and versatile for inhibiting troublesome shale formations. We made significant changes in the generally recommended compositions for these systems and developed a systematic approach to applying them.

Can you drill cement with PHPA mud?

Do not drill cement with PHPA muds, unless the system will be replaced after drilling out, because PHPA muds are sensitive to high pH, especially in the presence of high calcium levels. If drilling cement with a PHPA system is unavoidable, pretreat the system with 0.251bmlbbl [0.7 kg/m3] sodium bicarbonate.

Which drilling fluid is compatible with PHPA?

It is compatible with most of the drilling fluid products, biopolymers, PAC, CMC. It maintains borehole stability by preventing shale swelling and erosion. PHPA maintains viscosity in solid free drilling fluid. As a Bentonite extender in low solids non-dispersed mud, it can be used along with small addition of Bentonite to suspend weight material.

Is PHPA a shale control mud?

As a shale -control mud, PHPA is believed to seal microfractures and coat shale surfaces with a film that retards dispersion and disintegration. KCl is used as a shale inhibitor in most PHPA mud designs.

What is a PHP mud system?

These concepts have a very important consequence. A PHP A mud system must contain enough PHPA to maintain inhibition by encapsulation and to keep surfaces coated with an adsorbed polymer. The PHPA concentration, however, cannot be so high that the viscosity of the water phase becomes excessive.