Application of response surface methodology for a feasibility study of producing stable semi-aphron fluids using natural materials

ABSTRACT

Due to the drilling problems in fractured reservoirs, multiphase lightweight fluids are essential. To produce lightweight fluids and to achieve the desired stability, a variety of chemical and natural surfactants are used. However, natural surfactants are more in demand due to environmental issues and challenges. The goal of this research is to produce a lightweight fluid using a combination of natural materials. Moreover, colloidal gas aphron (CGA) based drilling fluids are prepared at 5,000 to 10,000 rpm stirring speed; therefore in this research, the production feasibility of stable multiphase fluid (called semi-aphron) was investigated at a lower stirring speed (1,500 rpm) without Xanthan Gum polymer. The applied natural raw materials, were Acanthophyllum bracteatum root (ABR), Glycyrrhiza glabra root (GGR), and Tetraclinis articulata fruit (TAF) powders that were mixed with Persian Gulf seawater. Three models of response surface methodology (RSM) were utilized to assess the effects of natural materials concentration (0 to 0.2%wt.) on the stability and drained volume (DV) of the liquid phase at 25°C and 70°C. The utilized models were central composite design (CCD), typical custom design (TCD), and modified custom design (MCD). Based on the results, the optimum concentration for ABR, GGR, and TAF were 0.2%, 0.1%, and 0.1% wt., respectively. The produced fluids, using the combination of natural materials, had better stability than the base fluid (using SDS). The optimum concentration of natural material delayed the drainage of the liquid by about 70% at ambient temperature (25°C), and by about 50% at 70°C. The MCD model showed better-predicted R² at ambient temperatures and 70°C (0.91 and 0.88, respectively) than the other two models, and would estimate the amount of DV better. The results showed that ABR and TAF had an inverse effect on DV at 25°C; thus, ABR and TAF increased semi-aphron stability, whereas GGR increased DV and semi-aphron instability. The results of this study can be considered for the application of native natural materials (ABR, GGR, and TAF) in the production of light drilling fluids, which reduces the environmental challenges of drilling fluids.

Graphical Abstract

KEYWORDS:

• Response surface methodology (RSM)
• stability
• colloidal gas aphron (CGA)
• Glycyrrhiza glabra root (GGR)
• Acanthophyllum bracteatum root (ABR)

Nomenclature

AAPRE: average absolute percent relative error

ABR: Acanthophyllum bracteatum root

ANOVA: Analysis of variance

CCD: central composite design

CGA: colloidal gas aphron

CMC: critical micelle concentration

DV: drained volume

DV_Exp: experimental drained volume

DV_Pred: predicted drained volume

GGR: Glycyrrhiza glabra root

IFT: interfacial tension

MCD: modified custom design

R²: correlation coefficient

RMSE: root mean square error

SD: standard deviation

SDS: sodium dodecyl sulfate

ST: surface tension

TAF: Tetraclinis articulata fruit

TCD: typical custom design

XG: Xanthan Gum

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567036.2022.2079774