Novel Water Shutoff Treatments in Gas Wells Using Petroleum External Solutions and Microemulsions

Abstract

The different water shutoff treatments based on in-situ gelation are attractive technologies; however, the field results often fall short of expectation. Reason of unsuccessful treatments might be that the flow resistance against water often develops not in the right time and reservoir space. Therefore, the primary aim of the research project was to develop such chemical systems, which will form the blocking phase triggered by mixing with water. As a novelty, water sensitive petroleum solutions and external microemulsions were developed, which are stable until they are diluted with water forming thus stable water external macroemulsions. Phase inversion of such metastable systems to stable ones in reservoir may radically restrict the water flow through their high viscosity and entrapment of the dispersed particles by the pores. The transformation and structure of phases were analyzed by photon correlation spectrometry, rheometry. The core studies confirmed that all metastable systems reduce the flow of water by 80-90% in water-saturated sandstone. Using chemical-free postflush the flow resistance remains substantial against water; meanwhile the permeability deterioration against gas is negligible.The petroleum microemulsions are in phase of pilot test in two gas wells in the largest Hungarian oil/gas reservoir (Algyő field) with the aim at restricting the substantial water production. The concept and the developed technology is similar to the earlier silicon microemulsion field test, which yielded 3 106 m3 incremental gas production in the same reservoir and measurable decrease in water production. The metastable systems may offer an excellent opportunity for water shutoff in matured gas fields and gas storage facilities. The unique properties of the techniques are that flow resistance may occur only in water saturated reservoir space and in case of technical failure; the flow barrier can be eliminated by oil and gas injection.

Specifics of Well Killing Technology During Well Service Operation in Complicated Conditions

“…Calculation of the stress state of the rock in the near-wellbore zone based on geomechanical modeling can make a significant contribution to the optimization of well killing processes. Among the works on the assessment of the stress state in the near-wellbore zone can be distinguished (Elchin et al, 2019;Lakatos et al, 2013;Fischer et al, 1973;Dorman and Udvary, 1996;Bouts et al, 1997;Orlov et al, 1991;Musabirov et al, 2019).…”

Comparative Study on Surfactants Mixtures in Aqueous Solution at Atmospheric Pressure and 10 bar Reservoir Atmosphere

“…Our research was dealt with the examination of emulsions which may occur during enhancement of petroleum exploitation [5,6]. In this process, the aqueous solution and the crude oil mixture get various stable emulsions.…”

Performance Evaluation of Water Control with Nanoemulsion as Pre-pad Fluid in Hydraulically Fracturing Tight Gas Formations

“…The experimental results indicated that water permeability dramatically declined, though gas permeability was slightly affected due to polymer adsorption on the pore surface . The traditional water shutoff agents including inorganic substances, polymers, or cross-linking agent–polymers for oil wells are found to impose a great negative impact on gas wells, especially for tight gas formations. − Subsequently, a modified polymer–cross-linking process was developed to not only induce gas channels within gel, but also re-establish gas permeability near the wellbore, selectively reducing water permeability . Another sequential gel/gas slug injection process was also proposed to perform water control in gas wells only in medium or high permeable porous media, which can significantly reduce the water–gas ratio .…”