Optimizing the Gel Strength of Water-Based Drilling Fluid Using Clays for Drilling Horizontal and Multi-Lateral Wells

Abstract

Drilling fluid constitutes an important part of the drilling operations. Drilling mud is circulated into the wellbore to minimize the formation damage, transport cuttings from the bottom to the top of the well, cool and lubricate the bit, and maintain the stability of shale formations. Gel strength property of drilling fluids plays a key role in drilling multilateral and long horizontal reservoir sections. Losing the gel strength will accumulate drilled cuttings and as a result, sticking of the drill string. Solving this issue takes a long time and increase the total cost of the drilling operation. It was observed that, by increasing the temperature to 200°F, the gel strength of calcium carbonate water-based drilling fluid reached zero lb/100 ft2. The objectives of this paper are to: (1) determine the rheological properties of calcium carbonate water- based drilling fluid over a wide range of temperature, (2) assess the effect of using clays (bentonite) to solve the gel strength problem associated with the current field formulation of calcium carbonate water- based drilling fluids, and (3) optimize the weight percent of bentonite. Rheological properties such as the apparent viscosity, plastic viscosity, yield point and gel strength were measured by using a high-pressure high-temperature rheometer. At low temperatures (85°F), the calcium carbonate water-based drilling fluid showed no change in the gel strength with time. However, at high temperatures, the gel strength starts decreasing with time. Rheological properties confirmed that the gel strength of the calcium carbonate water-based drilling fluid reached zero lb/100 ft2 by increasing the temperature to 200°F. This issue was solved by adding different concentrations of bentonite. The bentonite concentration was varied from 3 wt.% to 10 wt.%. At low bentonite concentrations (3.33 wt.%), the gel strength still reduced with time. At high bentonite concentration (10 wt.%), the gel strength increased with time. The optimum concentration of bentonite was 6.66 wt.%, which yielded a flat rheology profile of the gel strength. These results confirmed that the rheological properties of the water-based drilling fluid were optimized by using clays (bentonite). The novelty of this research is the complete investigation of the drilling fluid properties especially the gel strength with time over a wide range of temperature. The results obtained can leads to the development of a cheap solution without any side effect.

A Novel Amphoteric Polymer as a Rheology Enhancer and Fluid-Loss Control Agent for Water-Based Drilling Muds at Elevated Temperatures

“…The yield point (YP) is a measure of the thixotropic properties of the drilling mud at flow conditions. The yield point depends on electrochemical charges in the drilling mud, and when these charges attract each other, the yield point increases Figure a–c clearly shows that the addition of PEX to the drilling mud increased the yield stress compared to other drilling muds at 180 °C.…”

“…Rheological properties PV, YP, AV, and gel strength are important properties of drilling muds to carry and suspend cuttings during drilling mud circulation when the pump is off. PV and YP are the slope and intercept of the plot of the shear stress versus the shear strain rate, respectively . In this study, YP, PV, and AV were calculated from the rheological data measured at different shear rates.…”

Utilization of Eco-Friendly Waste Generated Nanomaterials in Water-Based Drilling Fluids; State of the Art Review

“…Gel strength (GS) measures the forces of attraction between particles in static conditions, unlike YP which measures them in dynamic conditions [ 29 ]. Therefore, gel strength refers to the ability to suspend drill cuttings during connections or other static conditions.…”

H2S Scavenging Capacity and Rheological Properties of Water-Based Drilling Muds

“…Drilling muds are an essential part of any drilling process, and they serve many important functions including cooling and lubrication of the rotating bit and downhole equipment, transport of drill cuttings to the well surface, and exerting pressure on the surrounding formation to prevent an undesirable influx of fluids or caving in of the borehole. − To achieve such objectives, drilling muds must possess special rheological properties, which are frequently achieved through the use of different mud additives. − For instance, for effective transport of drill cuttings, the drilling mud must display a shear thinning behavior. , Additionally, when circulation is stopped, the fluid should possess a sufficient viscosity to attain a gel-like structure that maintains the solids suspended and prevents their return to the bit area. , This unique rheological behavior can be obtained by a proper mud formulation using different additives; each one serves a certain purpose. − …”

“…13,14 Additionally, when circulation is stopped, the fluid should possess a sufficient viscosity to attain a gel-like structure that maintains the solids suspended and prevents their return to the bit area. 4,15 This unique rheological behavior can be obtained by a proper mud formulation using different additives; each one serves a certain purpose. 16−19 A common scenario often encountered while drilling subterranean formations is the infiltration of drilling muds by pockets of hydrogen sulfide (H 2 S).…”