Development of High-Performance Water-Based Mud Formulation Based on Amine Derivatives

Abstract

Abstract Many benefits by use of Oil-Based Mud (OBM) in drilling oil and gas wells have been identified in the oil industries worldwide. However the current ever increasing environmental legislations in preventing OBM application in the industries have dictated the use of water-based drilling fluid as the most environmentally acceptable alternative. On the other hand, drilling with water-based systems in shaly formations may cause many problems such as wellbore instability and high torque and drag. Therefore the most optimum alternatives would be different kinds of inhibited water-based systems in which adverse effects of shaly formations can also be controlled. These water-based alternatives are called High-Performance Water-Based Mud (HPWBM). Also the OBM properties is the final goal of the researchers to reach in their investigations to design a suitable HPWBM since OBM is the ideal drilling fluid to drill problematic formations. In this investigation attempts have been made to develop and formulate a water-based drilling fluid in which a suitable amine derivative has been successfully added to the system as a strong shale inhibitor agent instead of other conventional alternatives. Besides shale inhibition, an important challenge when using amine compounds in HPWBM is to overcome the thermal instability. Such a system must be formulated to achieve the right concentration of each mud additive to satisfy the necessity of a system that provides proper thermal stability during the drilling operation in high temperature sections. The newly HPWBM that was developed in this study comprises a specific concentration of a unique poly-ethoxylated alkyl diamine compound for shale inhibition, an amphoteric/polymeric shale encapsulator, a high-performance lubricant/deflocculating agent and special fluid loss additive to reach thermal stability up to 200°F. The designed system has exhibited optimum rheological properties and shale recovery in laboratory testing that was very close to that of OBM. The designed system has optimally improved the performance of previously formulated HPWBMs. Introduction To solve the drilling problems associated with shaly formations, various Non-Aqueous Drilling Fluids (NADF) have been used in the fields by the operators. In addition to shale inhibition, suitable lubricity and temperature stability were seen by using these systems (Friedheim et al. 1991; Friedheim and Conn 1996). However these advantages are realized as the ultimate goal in HPWBM researches, NADF have disadvantages, such as high cost, environmental limitations, disposal problems, and health and safety issues (Beihoffer et al. 1992; Patel et al. 2001). Shaly formations have a high tendency to absorb water from the surrounding fluid. This will happen by either rapid swelling or shale deflocculation mechanism which will result in problems such as bit balling, wash out, high torque and drag, etc (van Oort et al. 1996a; Steiger and Leung 1992). To reduce such anxious problems many chemicals have been used in the previous decades. These chemicals act via different mechanisms. The most widely used method was based on the addition of high concentrations of salts as like as sodium chloride (NaCl) and potassium chloride (KCl) to the drilling fluid. However using these salts in high concentrations causes environmental problems and results in high cost of disposal (Patel et al. 2007). The first generation of the shale inhibitor fluids introduced into the industry included sodium chloride/starch-, silicate-, lime- and calcium sulfate-based gypsum mud (van Oort et al. 1996b). However environmental problems and limitations in mud formulation restricted their wide application.