Development of a Weighted Barite-Free Formate Drilling Mud for Well Construction under Complicated Conditions

Abstract

Construction of oil and gas wells at offshore fields often involves high formation pressure and the presence of swellable clay rocks in the section. In addition, productivity preservation is also an important aspect. For this purpose, it is necessary to reduce the solids content of the drilling mud. The purpose of this work is to develop, improve, and study compositions of weighted drilling muds with low content of solids, on the basis of organic salts of alkali metals and polymers for the construction of wells prone to rock swelling and/or cavings, as well as drilling fluids for drilling-in the formation. In order to achieve the set goal the following is required: Analysis of existing drilling muds of higher density for drilling wells in unstable rock intervals and for drilling in the productive formation; analysis of experience in using drilling systems on the formic acid salts base and substantiation of requirements for flushing fluids during well construction; development and investigation of drilling mud compositions on the formate base; and the evaluation of inhibiting effect of systems containing organic salts, polymer reagents, and calcium carbonate on clay samples. The developed drilling mud is characterized by a high inhibiting ability that allows minimized mud-weighting by the natural solid phase. This reduces the volume of prepared mud and facilitates the regulation of its properties by reducing the dispersion of drilled cuttings; it eliminates problems related to hydration and the swelling of active clay rocks; and stabilizes unstable argillites prone to caving. The low solids content, low filtration rates, and inhibitory nature of the mud allows high stability of the rheological properties of the mud, and preserves oil and gas reservoir productivity under conditions of elevated formation pressure.

Study of a High-Temperature and High-Density Water-Based Drilling Fluid System Based on Non-sulfonated Plant Polymers

“…The temperature resistance and reduction in filtration loss of the filtrate reducer are judged by rheological properties and the filtration loss [ 23 ]. The above bentonite-base slurry with filtrate reducer (FLO-H) was aged at 200 °C for 16 h. The rheological properties of the bentonite-base slurry with filtrate reducer before and after the aging process were measured at six specific shear rates, i.e., 600, 300, 200, 100, 6, and 3 rpm, using a ZNN-D6 size rotational viscometer (Qingdao Hengtaida Electromechanical Equipment Co., Ltd., Qingdao, China), which was applied to calculate apparent viscosity (AV), plastic viscosity (PV) and yield point (YP).…”

Application of High-Density Brines in Drilling and Completion Fluids: Current Insights and Future Perspectives

“…The formate-based brines demonstrate numerous advantages over the other types of HDBs. 33 The formate-based HDBs are safer to manage and transport due to their less corrosive nature. They demonstrate less toxicity and higher biodegradability; therefore, they pose extremely low negative short-term and long-term impacts on the environment.…”

“…77 They compete well with conventional fluids, leading to improved mechanical drilling speeds and reduced contamination near the formation zone. 78 Formate-based systems combined with polymer additives have inhibiting properties toward shales, reduced corrosive activity, and enhanced lubricating ability. They induce less damage to productive horizons, leading to an improved oil-well productivity.…”

Salt Deposits and Brine Blowout: Development of a Cross-Linking Composition for Blocking Formations and Methodology for Its Testing

“…The studies include the addition of formation fluid (brine) to a weighted drilling fluid with a density of 2050 kg/m 3 [40].…”