Mixed scaling control technology of produced water in different layers of the Dingbian oil production plant

Water injection is a common method for enhancing oil recovery in oilfield production processes. However, in the process of water injection development, the incompatibility between injected and formation water can easily cause formation pores and wellbore scaling problems, which compromise the oilfield production process. Considering a scaling well area in northern Shaanxi as example, scaling mechanism analysis and scale inhibition technology research were performed. The scale samples were subjected to water quality testing by total ion analysis and static compatibility experiment, in addition to scaling trend prediction and X-ray diffraction analysis. The calcium carbonate scale was found to be the main scale in this region and the main reasons for scale formation were: high content of CO32- and HCO3- in reinjection wastewater, high content of Ca2+ and Mg2+ in the produced water of the oil well, and poor compatibility between the formation water and reinjection wastewater. The formation of calcium carbonate scale was prevented by chemical scale inhibitor compounding and good chelation. Hence, the screened inhibitor showed good scale inhibitory effect and can provided technical support for the water injection process.