GLDA/HF Facilitates High Temperature Acidizing and Coiled Tubing Corrosion Inhibition

Abstract

An existing limitation of chelant-based fluids available for sandstone acidizing with hydrofluoric acid (HF) is the presence of sodium in the concentrate of the aminopolycarboxylate fluid, which is common in all chelating agents soluble below pH 3.5. The presence of sodium complicates stabilization of the fluid during acidizing processes because of the myriad of chemical reactions that can impact the outcome of a treatment. The use of chelating agents has expanded the temperature range as well as the type of clay minerals that can be exposed to an HF fluid; however, limitations still exist. Core flow testing at 360°F and corrosion testing from 265 to 360°F were conducted. Flow tests were performed using outcrops of two types of sandstones and inductively coupled plasma (ICP) analysis was conducted to elucidate the ionic composition of the spent fluid. Results reported stem from core flow testing with glutamic acid diacetic acid (GLDA) containing HF at very high temperatures (360°F). To encompass a broad range of mineral composition, two types of sandstone cores were employed-heterogeneous (Bandera, 65% quartz) and clean (Leopard, 95% quartz). Corrosion inhibition of the GLDA/HF fluid for use with coiled tubing (CT) was achieved up to 320°F, employing varying classes of inhibitors. The GLDA/HF fluid exhibited lessened corrosion tendencies and could be inhibited for at least 6 hours at 360°F for drillpipe (mass loss rates of 0.025 to 0.05 in./ft 2 were obtained).The presence of sodium in GLDA/HF could be managed, leading to effective permeability improvement of the Bandera core, while the Leopard core underwent a decrease in overall permeability; this latter observation was attributed to the formation of metal fluorides. Neither the presence of CaCO 3 in the Bandera substrate or the use of KCl brine substituting for the usual NH 4 Cl led to permeability impairment. The overall results indicated that 1% HF and 0.6 M GLDA with an auxiliary agent could circumvent the expected problems associated with HF acidizing and modification, volume minimization, or elimination of preflushes. The use of the GLDA chelant facilitates, when using CT to deliver fluid to hot zones (which can be susceptible to formation damage if aggressive fluids based on HCl or formic acid are used, or if acetic acid is employed), could be jeopardized because of the difficulties inhibiting the corrosive effects of HF, HCl, formic, or acetic blends.

From initial treatment design to final disposal of chelating agents: a review of corrosion and degradation mechanisms

“…Reyes et al 70 tested a GLDA/HF blend and showed acceptable corrosion rates on coiled tubing and drill pipe at temperatures below 160 C (320 F), but corrosion inhibitors were required at higher temperatures. The corrosivity of 25 wt% GLDA on L-80 at 127 C (260 F) in the presence of sour gas (7 mol%) and carbon dioxide (3 mol%) was examined by Nasr-El-Din et al 71 and found to require 1% corrosion inhibitor containing alkoxylated fatty amines, alkoxylated organic acid, and thiourea N,N 0 dibutyl since the corrosion rate was too high (152.5 mmpy (0.168 lb  À2 )) without it.…”

“…MGDA has also been designed for use as a stimulation fluid alongside HF by Pascarella and Reyes 149 and as a self-diverting mixed acid system. 150 MGDA, GLDA, and ASDA have also shown promise as stimulation and fracturing fluids. 151,152 MGDA can also be used in ASP (Alkali Surfactant Polymer) solutions as a scale inhibitor.…”

Sr(ii) extraction by crown ether in HFC: entropy driven mechanism through H2PFTOUD

“…Therefore, by substituting the conditional extraction equilibrium constant calculated from eqn (16) into eqn (31) and tting the plot of log K 0 ex vs. 1000/T (Fig. 5), DH and DS can be obtained.…”

“…Recently, Zhu et al developed a method for preparing sodium and potassium salts of H 2 PFTOUD, which is a novel peruoroalkyl compound with weak bioaccumulation ability. 12 Moreover, several examples of the use of H 2 PFTOUD can be seen in patents, including as a functional coating on the surface of a semi-permeable membrane composite, [13][14][15] a component in treatment uids used in subterranean formation operations, 16 and a component in modied thermoplastic elastomers for increased compatibility with supercritical uids. 17 However, there is no applicable information on solvent extraction using H 2 PFTOUD, despite its interfacial properties, which are suitable for application in separation and concentration technology.…”

Sandstone matrix acidizing knowledge and future development

“…Wormholes can be formed by EDTA and HEDTA at temperatures up to 400°F. Frenier and Hill (2002) and Mahmoud et al (2011) used chelating agent Reyes et al (2015), Rignol et al (2015) and found it effective in increasing sandstone permeability at high temperatures. It is highly admirable that many researches had focused on the development of acids which can be applied in hightemperature reservoirs.…”