Evaluations of Polyacrylamide Water-Based Drilling Fluids for Horizontal Drilling in the Shaly Wolfcamp Formation

Abstract

Summary The Permian Basin, located in southeastern New Mexico and west Texas, is treated as the largest province of oil and gas production in the United States (US). The majority of hydrocarbon production from the Permian Basin is from the Wolfcamp shaly formation. Drilling horizontal and extended reached wells is continuously increasing day after day in the Permian Basin. Oil-based mud (OBM) is used to drill these horizontal wells for enhancing shale inhibition, reducing torque and drag, and supporting thermal stability of mud rheology. Due to environmental regulation for limiting use of OBM, the petroleum industry has tried to develop water-based fluid (WBF) that approaches the performance advantages of OBM. The main objective of this research is to formulate and develop WBF by using polyacrylamide anionic friction reducer (AFR) for drilling the lateral sections of horizontal wells in the shaly Wolfcamp formation. Shale inhibition, barite sagging, lubricity, and thermal stability of the formulated WBF with AFR will be studied to evaluate the developed WBF. Laboratory experiments were conducted to develop and evaluate the performance of the formulated WBF with AFR. The shale inhibition capabilities of the developed WBF with AFR were evaluated by using zeta potential, shale dispersion test, and immersion test. The results prove the capability of the formulated WBF with AFR to prevent both shale swelling and shale dispersion. AFR limits water penetrations to shale through encapsulation. The mixing procedures of AFR with WBF affect both the thermal stability of mud rheology and shale inhibition. Adding AFR to WBF helps to suspend weighting materials and mitigate barite sag. Besides, AFR decreases torque and drag by decreasing the coefficient of friction (COF). Furthermore, AFR supports enhanced stability of mud rheology with time up to 14 days at temperatures up to 180°F. The formulated WBF with AFR can be used for enhancing shale inhibition, supporting thermal and time stability of fluid rheology, improving lubricity, and minimizing barite sagging for drilling shaly Wolfcamp formations. This study presents a promising WBF to replace OBM to drill lateral sections in the Permian Basin.