Abstract
ABSTRACT Inadequate zonal isolation in oil wells can provoke safety and environmental problems. New cement slurries can avoid such problems. In this work, novel cement slurries were prepared in the presence of seawater with in situ-formed epoxy resin–ethylenediamine. The new slurries were tested in relation to their mechanical properties and characterized by FTIR, XRD, TG/DTG, porosimetry by N2 adsorption-desorption and solid-state 29Si and 27Al NMR. Some kinetic features of long-term contact of the slurries with in situ-generated mud-acid were performed to evaluate the performances of the new slurries in routine acidizing procedures in oil well industry. The experimental kinetic data were well fitted to order-variable exponential kinetic model and a factorial design of four variables (24). In these studies, it was possible to evaluate in detail how some important experimental factors act on the quantities of acid that interact with the pastes, as well as to verify how these factors affect the speed with which the mud-acid interacts with the slurries. The results strongly suggest that the interactions occurred at epoxy/ethylenediamine cement slurry/mud-acid interfaces are due to surface reactions with preservation of the chemical structures of the cement slurries, even after long-term contact with mud-acid. The new cement slurry present good features to be used in environmental-friendly procedures in oil well field.
Highlights
Among other features, cement slurries have been used to block undesirable underground streams of oil, gas, water or the like [1,2]
We report the preparation of cement slurries additived with epoxy resin and a diamine in the presence of seawater
3.1 Characterization of the cement samples Characterization has been an important tool for understanding the relationship chemical compositionmolecular structure associated of hydrated cement slurries
Summary
Cement slurries have been used to block undesirable underground streams of oil, gas, water or the like [1,2]. Acid fracturing has been a technique in oil industry for solving problems of some oil wells with impaired production This technique consists in using acidic fluids to crack some rocks in specific underground environments, employing inorganic acid-based fluids, typically mud-acid, a mix of HCl and HF aqueous solutions [4]. Such routine operations have been understood as an important aspect to oil and gas industries due to possible undesirable long-term reactions between the cement slurry in the annulus section and the acidic fluid, leading to the development of wormholes in some fractured interfaces. Suitable performances of oil well cement slurries have been reached by the use of some additives [6,7]
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