Study on clogging injection lines by chemicals in the wellbore

Abstract

The objective of this research project is to assess the risks and understand the causes of the formation of precipitates in lines of injection of emulsion breakers in producing wells. Such a phenomenon can cause the clogging lines and injection valves of this type of fluid. During the injection process, the fluids are subject to great variations in pressure and temperature, which can cause some changes in the physical properties of the emulsion breakers, such as phase change, which in turn can promote the formation of particulate solids that deposit along the line and valves, causing malfunction and even failure of the injection systems. This work is within the scope of the research line on Artificial Elevation and Flow Guarantee of EPIC (FAPESP/EQUINOR/UNICAMP) and the theme was presented by EQUINOR as a problem that is already occurring in the Pelegrino field, with the injection of emulsion breakers .The papers in the literature on the precipitation and blocking of chemicals in the injection lines are concentrated on the scale inhibiting chemicals, where there are reports on the blocking of the lines, valves and accelerated corrosion of the injection systems, however, the studies that reports such problems with the use of emulsion breakers are scarce. There are some hypotheses presented for the case of incrustation inhibitors, which can be verified if it will occur for emulsion breakers, such as: change in the phase balance of the emulsion breaker, due to variations inpressure and temperature gradients along the injection umbilical; chemical incompatibility with another added chemical; chemical incompatibility with some valve sealing material; valve opening mechanism itself, which works by pressure differential between the well and the injection system; use of inadequate filters in the injection lines; and even the formation of particulates in the chemical during its storage (aging effect). To test these hypotheses, some methods have already been proposed in the literature such as filtration, product stability test, distillation test to evaluate the formed vapors, always in order to test the chemicals in more representative field conditions, within the injection lines. The afore mentioned hypotheses also show that there is no holistic view of the problem, since it involves everything from the chemical composition of used commercial products (which are not known about formulations), to the mechanics of the injection system itself, making the problem even more challenging. With this guidance, the present proposal is integrated with the other research works that are under development within EPIC, such as master's dissertations, doctoral and postdoctoral thesesin the area of emulsions. The postdoc will initially raise, based on the literature review, the main hypotheses that may be causing the failure of the valve by the injected chemicals, and devising and planning experiments to validate these hypotheses, and from there propose answers to avoid the failures injection system. With this it is expected that this work will contribute to reduce the operational costs and maintenance requirements of the pumping system, since with the continuous injection of chemicals, the pumping system will work in a stable manner. (AU)