Developing novel high performance to drilling muds for applications in high pressure and high temperature oil wells

Abstract

In the present research, a novel organo-layered mixed metal layered double hydroxide material (based on an Mg/Al layered double hydroxide (LDH) modified with adamantane acid and described in US Patents: 2017 / 267910 A11, 2017, US 2018 /10,087,355 B2, US2019/0055451A13) has been studied for use in an invert emulsion drilling fluid for applications in high pressure high temperature (HPHT) wells. In particular, the ability of the new material to maintain the rheological properties and emulsion stability of the formulated fluid under high pressure and high temperature conditions has been investigated. The experimental phase has assessed and compared two rheology modifiers, firstly the novel organo-LDH rheology modifier developed by the Greenwell group, Durham University, and jointly patented with Saudi Aramco, and secondly a commercial rheology modifier (Bentone 42).
The drilling fluid formulations used to compare and evaluate the performance of the new material 1,2,3 were based on commercial formulations, which usually utilised Bentone 42 as the rheology modifier. Bentone 42 was compared to the new material in a range of formulations in order to observe the compatibility of the new rheology modifier with all the formulation constituents. Also, performance of the new organophilic layered mineral rheology modifier based on the Mg/Al LDH was assessed over a concentration range to determine the rheological profile at low shear rate, in order to define the further work needed to investigate the performance of this new rheological modifier.
This research project assessed the resistance to degradation and the rheological behaviour of the formulation with the new rheological modifier1,2,3. Experiments were undertaken drawing attention to rheological behaviour, such as rheological measurements in low temperature low pressure and high pressure high temperature conditions, focussing on yield point, plastic viscosity and thixotropy properties. Also, some experiments were conducted to evaluate the contamination tolerance for both the new and commercial rheological modifiers. Emulsion stability with the new rheological modifier was measured in oil, a colloidal suspension and with all the formulation compounds from the drilling fluid evaluated. The suspension weighting capacity was measured with a sag test correlating with the yield point property. Finally, a fluid loss test was undertaken to assess if the new rheological modifier can minimize fluid loss.
This thesis demonstrates the rheological behaviour and the stability of the new rheological modifier at different temperatures and pressure, and the concentration dependent interaction of a rheological modifier in a drilling fluid formulation. Although, the new rheological modifier shows instability in the formulation1,2,3, the work undertaken here-in aids define future work required to develop this new rheological modifier. This will lead to more knowledge about the material, such as particle size dispersion and ion exchange of the alkaline-earth diamondoid compound for the new rheological modifier, and optimization of the drilling fluid formulation cited in the patents mentioned above, which might influence the material behaviour to develop viscosity and suspension capacity.