Streaming Potential Measurement to Quantify Wetting State of Rocks for Water Based EOR, In-house Novel Setup Experience
M. Rahbar, A. Jafarlou, M. Nejadali, S. Esmaeili, H. Pahlavanzadeh and S. Ayatollahi
Event name: IOR 2017 - 19th European Symposium on Improved Oil Recovery
Session: Low Salinity
Publication date: 24 April 2017
Info: Extended abstract, PDF ( 1.67Mb )
Price: € 20
The wetting condition of the reservoir rock is the key to the success of any EOR technique and the ultimate oil recovery. Wettability is dictated by the surface chemistry related to the interactions between the fluids and the rock surface which determines the stability of the water film between the rock and the oil phase. Streaming potential measurement is one of the electrokinetic techniques used to determine the average zeta potential of porous rock which can provide reliable information on fluid-rock interaction and wettability state of the rock surface. Streaming potential measurement has recently been introduced in the oil reservoirs applications and there are still significant uncertainties during the measurements and interpretation of streaming potential results. The primary purpose of this work was to establish a setup to measure the streaming potential of porous media and evaluate voltage measurements that could be used at different conditions. Moreover, according to significant differences of reported zeta potential (depending on measurement methods, measurement conditions and nature of minerals), comprehensive investigations were performed on zeta potential measurements of carbonate samples adjacent to the potential determining ions-PDI by streaming potential technique. Streaming potential coupling coefficients have been measured for 60 samples of calcite and quartz sandpack in adjacent to the fluid with different concentration of PDI and in the pH range of 1.5 to 11. The next step was to develop an understanding of the behavior of coupling coefficient under condition of brine salinity and pH to determine the rock fluid interactions and wettability alteration mechanism. To achieve this goal, the measured streaming potential and zeta potential of each test was compared to the results of adhesion test as experimental measurement of wettability and analysis of equilibrium solution. The experimental setup proposed in this study permits accurate measurements of streaming potential without any effect of polarization. The paired-stabilization and the pressure-ramping methods validate the voltage measurements obtained from the setup. The results showed that the wettability is directly and quantitatively affected by streaming potential measurements and the electrical properties interpreted from these measurements can predict wettability alteration mechanisms such as double layer expansion and ion exchange for various fluids. In addition, an accurate empirical expression is proposed for the measured coupling coefficients which predict streaming potential coupling coefficients and zeta potential of quartz sample in the salinity range from 0.0001 M to 5.5 M of NaCl.