Minimizing the Barite Scale in Carbonate Formations during the Filter Cake Removal Process

Area of Science:

• Petroleum Engineering
• Materials Science
• Geochemistry

Background:

• Barite scale formation is a major challenge in the oil and gas industry, reducing well productivity and causing equipment erosion.
• Scale can form in reservoirs or production equipment due to incompatible brine mixing, drilling fluid invasion, or during filter cake removal processes.
• Secondary damage from chelating agents interacting with reservoir formations during filter cake removal is a critical concern.

Purpose of the Study:

• To evaluate a novel solution of diethylenetriamine pentaacetic acid (DTPA) and ethylenediamine tetraacetic acid (EDTA) for preventing barite scale formation in carbonate formations.
• To assess the effectiveness of the DTPA-EDTA solution during the filter cake removal process, specifically addressing secondary damage.
• To characterize barite scale and analyze the performance of the proposed scale prevention solution.

Main Methods:

• Laboratory experiments were conducted using carbonate core samples.
• Techniques included particle size distribution, scanning electron microscopy (SEM), X-ray diffraction (XRD), core flooding, Nuclear Magnetic Resonance (NMR) spectroscopy, solubility tests, and Inductively Coupled Plasma (ICP) spectroscopy.
• The study focused on evaluating the barium loading capacity and inhibition of barite deposition in the presence of calcite.

Main Results:

• The DTPA-EDTA solution demonstrated a high barium loading capacity of 35,000 ppm in the presence of calcite.
• EDTA addition inhibited barite deposition and enhanced calcite reaction rates.
• NMR analysis revealed that a 20% DTPA-EDTA mixture stimulated macropores, increasing return permeability by 1.4-1.8 times, with negligible precipitation in micropores.

Conclusions:

• The novel DTPA-EDTA solution effectively prevents barite scale formation in carbonate formations during filter cake removal.
• The solution enhances reservoir properties by increasing macroporosity and return permeability.
• This approach offers a promising method to mitigate well productivity loss and equipment damage caused by barite scaling.