Stimulation of Seawater Injectors by GLDA (Glutamic-Di Acetic Acid)

Abstract

Seawater is injected to maintain the reservoir pressure that supports the oil production from carbonate and sandstone reservoirs. In certain regions, the seawater contains more than 4,000 ppm sulfate, and the formation contains more than 19,000 ppm calcium; this will cause calcium sulfate precipitation at the reservoir conditions. The precipitate at the reservoir conditions will be anhydrite, and it will cause formation damage that will reduce the well injectivity. Stimulation treatments are required to recover the well injectivity; this requires stopping water injection to perform the stimulation treatments, and also it requires flowing back the well after stimulation treatment.In this study, we are proposing a new method that we can use to stimulate water injectors without stopping the water injection. The new method includes adding a chelating agent to the injected seawater at the wellhead at 15 wt% concentration. The fluid will be injected at the surface with the seawater with a specific dose to achieve the required concentration. Several solubility and coreflooding tests were performed with actual carbonate cores and GLDA (glutamic-di acetic acid) chelating agent at different temperatures. The chemical injection does not need coiled tubing and can be injected at the surface with the seawater. The chelating agents will sequester all calcium in solution and will prevent the calcium sulfate precipitation. GLDA chelating agent will be used with seawater, with no need to use treated or fresh water. Also, flowing back the well is not required because the fate of GLDA in the aquifer is soluble.Solubility tests up to 250 F at high pressure showed that the GLDA is stable with seawater. Coreflood experiments and computed-tomography scans showed the ability of GLDA in the creation of dominant wormholes through 6-and 1.5-in. carbonate cores at 212 and 150 F, respectively. GLDA chelating agent can be used to stimulate seawater injectors without additives because this chemical is stable and mild with the well tubulars. Previous corrosion studies on GLDA showed that its corrosion rate is in the allowable range without adding corrosion inhibitors.

Applications of Chelating Agents in the Upstream Oil and Gas Industry: A Review

“…Mahmoud et al used seawater and GLDA injection to treat sandstone formations. HCl-based formulations caused damage because of the compatibility with seawater and formation water as well.…”

Reaction Kinetics and Coreflooding Study of High-Temperature Carbonate Reservoir Stimulation Using GLDA in Seawater

“…The low corrosiveness nature of chelating agents enables using it in different aspects of the oil and gas industry including scale removal from electrical submersible pumps in oil production wells [18], Scale inhibition [19][20], Filter cake removal after drilling operations [21]. In addition, aminocarboxylic acids were used to improve oil recovery from subsurface hydrocarbon reservoirs [22][23].…”

Development of Chelating Agent-Based Polymeric Gel System for Hydraulic Fracturing

“…The results clearly indicate that the viscosity thickening effect can be controlled with the concentration of GLDA, and for optimum conditions, it should not be more than 30 wt %. All of the stimulation operations in the field are performed with a concentration of 20 wt % because it was found to be the optimum in case of stimulation [37][38][39]. In this case, 20% of GLDA also showed the optimum results.…”