The First Successful Chemical EOR Pilot in the UAE: One Spot Pilot in High Temperature, High Salinity Carbonate Reservoir

Abstract

In 2014, Total performed a surfactant-polymer single-well pilot to test the effectiveness of a surfactant formulation developed in-house, and including a new proprietary class of surfactants with improved temperature- and salinity-tolerance characteristics. This paper unveils the results of this pilot which targeted a high temperature, high salinity carbonate reservoir. The operations were performed on an oil bearing reservoir of Lower Cretaceous age, in an offshore field operated by Total since 1974 and located 180 km offshore Abu Dhabi. Dedicated topsides were designed and installed for this EOR project. Extensive in-house laboratory studies were performed to select and synthesize the chemicals. Specific simulations, using laboratory results as input, were carried out to predict the pilot performance, design the Single Well Tracer Tests (SWTTs), and size the equipment. In this paper we will discuss the workflow used to select the most appropriate well and present the methods and results used to characterize the reservoir. Then we will relate it to the surfactant-polymer injection field operations. Finally the reservoir monitoring activities that were necessary to preserve reservoir integrity and demonstrate the pilot efficiency will be described. The strong decrease in remaining oil saturation measured after the chemical EOR pilot clearly proves the effectiveness of the chemicals synthesized by Total to mobilize the remaining immobile oil after water-flood. These positive outcomes change the perception of CEOR in hot, saline Middle-East carbonate reservoirs, and could be a "game changer".

Optimization and comparison between polymer, surfactant-polymer and water flooding recoveries in a pre-salt carbonate reservoir considering uncertainties.

“…The results of this research for the Cerena-I model can be compared to findings of real field applications (the Lula model had an EMV lower for SP and PF than WF, therefore, is not compared). The most recent report of SP injection was the Single Well Tracer Test of an offshore carbonate reservoir in Abu Dhabi (AL-AMRIE et al, 2015). Both, their research and the present agreed on: salinity brine for the chemical injection lower than the one encountered at reservoir conditions it is preferential.…”

“…As an example, Dickson (2010) do not include the SP injection, Taber (1997) and Al Adasani (2011) proposed screenings recompiling several parameters from other authors, where they recommend sandstones as reservoir rocks. The fact there is little report of field scale application on SP flooding, strictly speaking (no alkali injection), most of them were done before 1990, none in Latin America and only four applications on carbonate reservoirs successfully carried out in the literature between 1970 to 2018 (FOSTER, 1973;RICHMOND, 1978;WKFMNYER, 1982;TALASH;STRANGE, 1982;THOMAS et al, 1982;RATERMAN, 1990;HOLLEY;CAYLAS, 1992;BOU-MIKAEL et al, 2000;GURFINKEL, 2007a;ZHU et al, 2012;ZHENQUAN et al, 2013;SHENG, 2013a;AL-AMRIE et al, 2015).…”

“…Concluding, new technologies regarding water treatment, capable of reducing water and energy consumption; a single chemical formulation is preferable, so no additional storage facilities are needed, currently polymer makes 10% of the chemical cost, while surfactant and alkaline cover the other 90% which brings cost issues deepen if the design does not cover the possible adsorption of the chemicals on the rock.Another field test was performed by Total S.A in the Middle East in 2014, which was the first offshore pilot on an offshore carbonate reservoir with high salinity formation brine of 230g/L, high temperature (80-90°C) and low permeability ranging from 30-100 mD(AL-AMRIE et al, 2015;MOREL et al, 2016). The formulation employed consisted of an SP slug of 1.35%w active surfactant in an 80 g/l brine and a polymer drive with softened seawater.…”

Co-Deposition Mechanisms of Calcium Sulfate and Calcium Carbonate Scale in Produced Water

“…− and H + combine to generate water and carbon dioxide gas Equation (5). Therefore, when the mixed scale is co-deposited, the pH value of the solution immediately decreases significantly at the beginning of the reaction, and a large number of small bubbles are generated.…”

“…The scaling problem caused by poor water stability and compatibility qualities can occur during fluid flow in a reservoir or wellbore as well as in the wellhead in petroleum operations [1][2][3]. Scale formation has been recognized as a major operational problem [4][5][6], which causes extremely serious consequences, such as reducing the oil production rate, oil well productivity, and turnover time of electric submersible pumps as well as plugging the perforations, premature failure of downhole equipment, and damage to the formation [7][8][9]. Frequent pipeline cleaning and replacement have increased the production and maintenance costs of oil and gas fields [10,11].…”