Research Into Lubricity, Formation Damage Promises to Expand Applications for Silicate Drilling Fluids

Abstract

Silicate drilling fluids have been used for more than 60 years. While the early versions of silicate-base systems proved very inhibitive, controlling mud properties was difficult because proper polymer additives were not available for maintaining rheology and fluid loss control. Furthermore, the solids control equipment available at the time was ineffective in removing solids. During the last decade, silicate-base systems have been re-engineered to provide a state-of-the-art and environmentally acceptable, water-base system that provides the inhibition approaching that of an invert emulsion field. The proposed mechanism of inhibition is the surface adsorption and chemical reaction of the silicate polymer with the formation surface. This "coating" effectively provides a thin pressure and chemical barrier on the surface of the wellbore. This formation/silicate interaction has raised a number of concerns regarding both the lubricity and the formation damage potential of the fluid. This paper investigates systematically both the lubrication characteristics of the fluid and the effect of silicate-base systems on formation production and evaluation. The results show promise in expanding the application of silicates as reservoir drill-in fluids and in the drilling of critical high-angle wells where lubricity is a primary design criterion. The data obtained in this study utilizes purpose-built lubricity and formation damage equipment to critically look at the problems. From this investigation the authors will reveal that the coefficient of friction of silicate fluids, as observed in the laboratory and measured in the field, does not differ significantly from that of other water-base fluids. Furthermore, the thin physical and chemical barrier formed during the reaction of the silicate polymer with the formation surface prevents fluids and fine particles from migrating into the formation, thereby minimizing damage to the producing zone. Introduction Silicate-based drilling fluids are probably the most misunderstood systems in the industry. Since the introduction of sodium silicate fluids in the the 1930's, silicate chemistry has demonstrated outstanding shale and formation inhibition characteristics. However, rheology and filtration properties had been difficult to control. Over the past few years, the development of modern polymer technology provided fluid design tools that proved effective in controlling both the rheological and filtration properties of silicate systems. Complementing advanced polymer technology was the design of new solids control and process technology that made silicate-base products effective well-bore stabilizing agents. Improvement in inhibition not only contributes to wellbore stability but also to minimizing dilution volumes, minimizing costs. The low dilution rates and toxicity of the system also provide an excellent fluid with minimal environment impact. In the 1980's, Wingrave's research on shale stability found that silicates, used in conjunction with the potassium ion and specific polymers, combined for an effective shale-stabilizing package.1 During the last decade the industry has effectively used sodium silicate in conventional polymer fluid formulations to provide an effective water-base shale stabilizing system.2,3,4,5 High-performance polymers and efficient solids removal equipment can now provide the required fluid performance and maintenance necessary for efficient and cost-effective silicate chemistry. Furthermore, its capacity to provide inhibition competitive with invert emulsion fluids makes silicate systems an ideal alternative for optimum wellbore stability, without the environmental limitations of an invert emulsion fluid.

Synergistic Effect of Nanoinhibitive Drilling Fluid on the Shale Swelling Performance at High Temperature and High Pressure

“…However, mud accretion is a concern with the TKPP drilling fluids. Earlier, in an attempt of minimizing the shale swelling difficulties, calcium chloride, silicate, potassium chloride (KCl), surfactant, lignosulfonate, and partially hydrolyzed polyacrylamide (PHPA) polymer drilling fluids were introduced. − Even though KCl drilling fluid performs well in terms of avoiding shale swelling, excessive KCl concentrations in the drilling fluids are strictly forbidden as a result of environmental concerns . Furthermore, heat-insulating polymers, like acrylamide and PHPA, are used to prevent the filtration and clay swelling .…”

Application of a Novel and Sustainable Silicate Solution as an Alternative to Sodium Silicate for Clay Swelling Inhibition

“…Over the decades, most of the drilling muds have been formulated with sodium silicate with different ratios of silica oxide to sodium oxide (SiO 2 /Na 2 O) in the silicates. 31 During the drilling operation in unconventional shale formations containing high contents of organic compounds, the drilling muds with silicate solution should show robust endurance toward oil contamination. Further, silicates are applied in oil well cementing operations as extenders and accelerators.…”

“…They have gained commercial acceptance and are widely used particularly for shale stabilization around the globe for onshore and offshore drilling operations. Over the decades, most of the drilling muds have been formulated with sodium silicate with different ratios of silica oxide to sodium oxide (SiO 2 /Na 2 O) in the silicates . During the drilling operation in unconventional shale formations containing high contents of organic compounds, the drilling muds with silicate solution should show robust endurance toward oil contamination.…”

Silicate-Based Fluid, Mud Recovery System Combine to Stabilize Surface Formations of Azeri Wells

“…Further examination identified mechanical and chemical destabilization of the reactive shallow soils as the root causes of this instability. This paper describes the application of a silicate-based drilling fluid system 1,2,3,4,5,7,8 in tandem with a unique Mud Recovery System (MRS) that combined to stabilize the problematic formation and allowed for the successful setting of the 20-in. casing without the lateral movement experienced in offset wells.…”