Investigating the Performance of Paraffin Inhibitors under Different Operating Conditions

Abstract

Mitigating paraffin deposition in production lines has remained a critical issue for the oil industry to control the associated production and transportation cost. Recently, injection of paraffin inhibitors in the transportation pipelines has been widely used along with other strategies to improve production. This study investigates the effect of operating temperatures and geometries on the performance of paraffin inhibitors. Moreover, the experimental temperature differences (i.e. changes in coolant temperature and bulk oil temperature) strongly influence the inhibitor efficacy indicating that these conditions must be optimized prior to field applications. The experiments were conducted with a Caspian Sea (CS) condensate at different temperature conditions using two paraffin inhibitors (Maleic anhydride co-polymers: PI-B and PI-C, where PI-B has a higher carbon chain length than PI-C). The inhibitor concentration of 500PPM and a 24h time duration is maintained for all the experiments. The deposit mass and wax content were analyzed. Wax mass flux increases with the increasing temperature difference in constant bulk oil temperature experiments. In contrast, the mass flux increases first and then decreases with the decrease in the temperature difference in constant coolant temperature experiments. Hence, it is important to consider the influence of operating conditions that may change the oil properties significantly and ultimately the magnitude of the paraffin deposition. Deposit mass (decreased) and wax content (increased) are significantly influenced by the presence of inhibitors. The inhibitor efficacy, that incorporates both deposit mass and wax content, is calculated at different operating temperature differences. It has been observed that the efficacy strongly varies with the operating region. Hence, it is necessary to select proper inhibitors based on the local operating temperature conditions during injection. This study provides a fundamental understanding between operating parameters and inhibitor efficacy. The usage of inhibitors is highly complicated and the knowledge obtained through this investigation disseminates crucial information on selecting proper inhibitor for field applications.

Wax Formation Mechanisms, Wax Chemical Inhibitors and Factors Affecting Chemical Inhibition

“…When the temperature increases, the deposited wax mass reduces while the critical carbon number increases. The increment in the critical carbon number is due to the longer paraffin inhibitor chain used, which hinders the lower n-paraffin components but leads to the increase in the deposition of higher n-paraffin components [113]. The critical carbon number determines the hardness of the wax deposition [114].…”

Substantiation and Selection of an Inhibitor for Preventing the Formation of Asphalt-Resin-Paraffin Deposits

“…The composition and strength of deposits depend on the composition and properties of reservoir fluid, geological, physical, and technological conditions of an oil field development. In oil production, the composition of ARPD mainly consists of 40 -60% solid paraffin and less than 10% microcrystalline paraffin, 10 -56% resins and asphaltenes, water, sand, and inorganic salts (Dubey et al,2017). ARPD, in well equipped and the BHFZ, are formed at the change in thermobaric conditions when the reservoir is cooled, resulting from the injection of cold water.…”

“…Reservoir water often has a high content of alkaline-earth metal chlorides (calcium, magnesium). Therefore, in contrast to anionic surfactants, non-ionic surfactants, which do not chemically react with alkaline-earth metal salts, are often used in oil fields (Dubey et al, 2017;Fang et al, 2014).…”

Study on wax precipitation characteristics of wax deposit in pipes

“…This deposition can create numerous problems of a wide variety such as reduced flow area, decreased transportation efficiency, increased pressure drop, and increased power consumption. In worst‐case scenarios, the pipe can be completely blocked, resulting in prohibitively expensive economic damages . Mechanical pigging is a widely used approach for wax remediation in the field .…”