This document is an expanded abstract.
Summary
In this paper we focus on the design and testing of a graphene based sensor for applications in oil industry. The sensor is designed to target the specific need of the oil industry related to monitoring and preventing scale formation in oil pipes. This causes drastic oil production losses and cleaning costs. The strontium ions are the key elements in the formation of the strontium sulfate scale on the inner wall of the oil pipes in certain oil wells. A specially designed graphene based sensor for scale monitoring is designed and tested with different strontium ion concentrations. The sensor showed a good wide sensitivity range from 2.5 kO to 18 kO resistance change in response to a strontium concentration ranging from 0.01 m/L to 0.25 m/L strontium concentrations. The sensor readings were consistent for a reference solution of deionized water with no strontium ions. The repeatability tests of the sensor were conducted successful and show good results even after a few days.
Introduction
In recent years, there was a continuous demand for scale monitoring in the oil pipelines. This is becoming a serious issue due to the high costs related to oil well maintenance for scale prevention. This is even worse at a later stage if the scaling has already started. In this case a much higher budget is required for cleaning the downhole oil pipelines in addition to the loss in oil production due to the well shutdown.
Graphene is one of the recent advanced materials with unique properties [1-3]. Its sensitivity is based on its structure and the fact that it is a single layer of carbon atoms. This unique structure makes it very sensitive to the environment and gives it many possible applications as a sensor for different ions and physical properties [4-7].
In this paper we focus on the application of this material to design a unique sensor for different ions in a water solution. This research is strongly driven by the oil industry needs for online monitoring of specific ions responsible for pipeline scale deposition [8-10]. This is such a challenge for the industry as most of the available sensors are not suitable for such harsh environment with high temperatures and high pressures. Currently there is no online continuous scale monitoring and the industry only rely on periodic oil well fluid sample testing and the injection of scale inhibitor chemicals as needed. In this project we have designed and tested a new graphene sensor for scale condition monitoring. This is done by monitoring the strontium ions that are responsible for scaling in some specific wells. The results of this work are discussed in details in the following paragraphs.
