Selection and Evaluation Criteria for High-Performance Drilling Fluids

Abstract

The degree of difficulty and costs of oil and gas wells have continually increased over the past decade. Development operations continue as the economics of exploring and producing for oil and gas have improved with advancements in drilling technology. Advanced drilling technologies such as rotary stearable assemblies, logging-while-drilling (LWD) tools, annular pressure subs and new bit designs have improved the economics of performance-driven wells. With consideration of reducing drilling problems such as torque and drag, stuck pipe, low rates-of-penetration, depleted sands and well bore stability; these wells are generally drilled with non-aqueous fluids (NAF). However, the inherent advantages provided by NAF are increasingly being offset by environmental risks and liabilities. The paper discusses key criteria to be considered when selecting high performance fluids (HPF) for performance-driven wells.Performance-driven wells are classified as wells that are technically challenging and inherently risky and costly.These types of wells demand the use of HPF to contain costs and deliver well objectives. Additionally, a new high-performance water-based mud (HPWBM) has been developed and field tested as a technically competent and environmentally compliant alternative to NAF on performance-driven wells.Through a process of product substitution, ChevronTexaco has achieved project objectives while improving the environmental impact of using HPF. Introduction The industry is increasingly drilling more technically challenging and difficult wells.Exploration and development operations have expanded globally as the economics of exploring and producing for oil and gas have improved with advancements in drilling technology. Advanced drilling operations such as deep shelf, extended reach, horizontal and deepwater are technically challenging, inherently risky and expensive. Environmental legislation governing drilling waste is continually restricting the discharge limits of spent muds and drilled cuttings.Operators are challenged with achieving a balance between minimizing the potential environmental impact of the drilling fluid against drilling objectives.The inherent advantages provided by NAF are increasingly being offset by environmental compliance restrictions. The drilling process generates large volumes of drilled cuttings and waste muds.Beginning in the late 1970's it became evident that waste discharges from drilling operations could have undesirable effects on the marine ecology.1The United States Environmental Protection Agency (EPA) adopted national discharge standards for the oil and gas industries in 1993 that established restriction on oily sheens and aquatic toxicity testing for waste discharges.The American Petroleum Institute estimates that about 150 million barrels of drilling waste were generated in 1995 from onshore wells in the United States alone. Operators have used a variety of methods for managing drilling wastes, typically driven by governmental regulations and cost considerations.Three options exist to manage offshore wastes from drilled cuttings and spent drilling fluid: marine discharge, down hole injection, and onshore disposal.2All options have advantages and disadvantages with regard to total life cycle environmental impact, safety, cost, and operational performance. The environmental impact of discharging cuttings and spent water-based mud (WBM) is minimal; however, the waste from certain types of NAF can create impaired zones in the proximity of drilling operations.Currently, most synthetic-based mud (SBM) drilled cuttings can be discharged into marine waters, however, SBM whole mud discharge is not allowed.WBM whole mud and cuttings can be discharged provided the fluid meets aquatic toxicity standards.From an environmental perspective, the worst case is oil-based mud (OBM).Wells using OBM are categorized as "zero discharge" and there can be no discharge of cuttings or whole mud.All OBM-contaminated waste must be transported onshore for disposal or be injected underground at the well site.

Synergistic stabilization of shale by a mixture of polyamidoamine dendrimers modified bentonite with various generations in water-based drilling fluid

“…Most of the current water-based drilling fluids show marginal success due to their inadequate characteristics (Patel et al, 2001;Fletcher et al, 2003;Young and Ramses, 2006). For this reason, attention has been focused to design new strategies to enhance shale stability (Schlemmer et al, 2003;Morton et al, 2005;Patel, 2009). Dendrimers, first discovered by Tomalia Dang et al, 2013), are different from traditional polymers in that they possess a multi-branched, three-dimensional structure with very low polydispersity, high polyfunctionality and huge surface areas (Chao et al, 2006).…”

Clay-Free High Performance Water-Based Drilling Fluid for Extreme High Temperature Wells

“…Water-based muds (WBMs) have also been shown to reduce the risk of lost circulation events compared to nonaqueous fluids (Morton et al 2005). Despite the benefits of WBMs, IEFs frequently remain a preferred option because of the drilling performance advantages they provide.…”

“…High performance water-based fluids have been defined as possessing drilling performance attributes and benefits of nonaqueous fluids (Marin et al 2009;Morton et al 2005). While exact formulations vary substantially, high performance water-based muds (HP WBMs) share many common features that are incorporated to help provide improvement compared to conventional WBMs and near-IEF performance in the areas of wellbore stability, cuttings integrity, ROP, and torque and drag reduction (Montilva et al 2007;Al-Ansari et al 2005).…”

“…In many cases, HP WBMs were used successfully in fields and formations that historically demanded IEF usage (Attia et al 2010). While HP WBMs have been successfully applied in many wells as an alternative to IEFs, HP WBMs have historically been limited to wells with temperatures less than 300°F (Morton et al 2005); however, IEFs do not have this limitation. This temperature limitation for HP WBM is largely driven by the polymers used for viscosity and fluid loss control.…”

Experimental Study of Electrical Properties of Oil-Based Mud in the Frequency Range From 1 to 100 MHz

“…Oil-based muds offer many advantages over other types of drilling fluids, significantly improving the overall drilling performance (Morton et al 2005). They may, however, impede resistivity-logging tools because of their high resistivity.…”