Ronald F. Scheuerman

Polyacrylamide/potassium-chloride mud for drilling water-sensitive shales

A shale-protective, water-base drilling fluid containing a high molecular-weight, partially hydrolyzed polyacrylamide and potassium chloride has been used in many wells around the world. A laboratory test for evaluating the ability of water-base muds to protect stressed shales under dynamic conditions was used in the initial development of the system. Field application of the polyacrylamide/potassium-chloride mud has been successful in stabilizing hard, sloughing shales in Canada and in reducing shale-related hole problems in several offshore areas. Recent use in the Canadian Arctic has extended the application to weighted muds for drilling soft, mud-producing shales.

Injection-Water Salinity, Formation Pretreatment, and Well-Operations Fluid-Selection Guidelines

This paper reports on injection-water/formation-clay compatibility criteria that are based on water and formation-clay analyses which were developed to determine whether an injection water has sufficient total cations and/or divalent cations to prevent formation-clay dispersion and permeability impairment and to determine when formation pretreatment is required to prevent impairment during the transition to injection water. These criteria also were incorporated into a scheme to determine the type of brine to be used for completion, stimulation, and work-over operations to prevent formation-clay deflocculation or to eliminate formation pretreatment.

Guidelines for Using HEC Polymers for Viscosifying Solids-Free Completion and Workover Brines

Solids free brines are increasingly used in well completion and workover operations. One technique to minimize downhole losses of expensive, high density brine is to spot a pill of viscosified brine across the thief zone. Hydroxyethylcellulose (HEC) is the polymer most frequently used for this purpose. This report discusses the properties of HEC thickened brines and presents guidelines for their use for completion and workover fluid loss control. 2 refs.