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Abstract Low Salinity Waterflooding is one of the emerging oil recovery techniques which has gained its popularity in the past decade. Many experiments and laboratory works have been conducted since its oil recovery potential was discovered in late 1960s. Wettability alteration in the reservoir is said to be the main cause in enhancing oil recovery. Nevertheless, the effectiveness of this type of oil recovery is very much dependent on the initial reservoir conditions, in particular, the connate water saturation, rock physics and connate water salinity. This work is to run simulations on ECLIPSE 100 simulator to show the effect of injecting low salinity water into a reservoir. A simple static model was created to mimic a real reservoir. Reservoir is of three phase with oil, gas and water and consists of one injector and one producer just to simulate the effect of injecting a low salinity water and a normal salinity, or seawater. Effect on oil recovery was observed by conducting sensitivity studies on rock physics; both injection and reservoir brine salinity; tertiary recovery option; polymer injection using low salinity water solution; and grid refinement. A difference of 14% in oil recovery is observed when lower salinity water is used to inject compared with normal salinity water. The effect on oil recovery also showed distinct difference when the connate water salinity is changed with difference up to 28% with low saline reservoir water. Polymer injection with low salinity water gave 4% increment in recovery compared to injecting with higher salinity water for the same concentration of polymer. This can indeed give better cost savings when opting for polymer injection, where a lower concentration or amount of polymer is needed with the use of low salinity water.
- Energy > Oil & Gas > Upstream (1.00)
- Water & Waste Management > Water Management > Lifecycle > Disposal/Injection (0.44)
Coupling Low Salinity Water Flooding and Preformed Particle Gel to Enhance Oil Recovery for Fractured Carbonate Reservoirs
Alhuraishawy, Ali K. (Missouri University of Science and Technology, Missan Oil Company) | Imqam, Abdulmohsin (Missouri University of Science and Technology) | Wei, Mingzhen (Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology)
Abstract The recovery of oil from carbonate reservoirs is usually low due to their extreme heterogeneity caused by natural fractures and the nature of the oil-wet matrix. Low salinity water flooding (LSWF) and preformed particle gels (PPGs) control conformance are two novel technologies that have recently drawn great interest by the oil industry. We developed a cost- effective, novel, enhanced oil recovery (EOR) technology for carbonate reservoirs by coupling the two technologies into one process. The objective of this paper is to provide a comprehensive understanding of the combined technology and to test through laboratory experiments the extent to which the coupling method can improve oil recovery. The laboratory experiments showed that the optimum water salinity for the application of the coupled method was 0.1 wt. % NaCl under experimental conditions. The water residual resistance factor (Frrw) increased as the water salinity and the fracture width decreased. The oil- wet carbonate cores provided a higher improved oil recovery than a water-wet carbonate cores during LSWF. The decrease in fracture width resulted in a higher oil recovery factor. Compared to traditional bulk gel treatments, PPG forms stronger plugging but will not form an impermeable cake in the fracture surface; therefore, PPG allows low salinity water to penetrate into the matrix to modify its wettability, thus producing more oil from the matrix. Results also show that oil recovery increased by 10 % during LSWF after the second waterflooding. Additionally, when PPG was injected, another 8 % of oil recovery was gained. As a result, combined the LSWF and PPG increased oil recovery by 18%. LSWF can increase only displacement efficiency but has little or no effect on sweep efficiency, while particle gels can plug fractures or in high-permeable channels to improve sweep efficiency but have little effect on displacement efficiency. The coupled method bypasses the limitations of each method when used individually and improve both the displacement and the sweep efficiency.
- Geology > Rock Type > Sedimentary Rock (0.70)
- Geology > Mineral (0.46)
- Geology > Petroleum Play Type > Unconventional Play > Fractured Carbonate Reservoir Play (0.40)
Abstract Optimization of any oil recovery process is based on understanding of recovery mechanisms, though the underlying mechanisms of improving oil recovery by low salinity water injection are still debated. Wettability alteration is one of the dominant mechanisms of any IOR/EOR process. In this paper, wettability alteration by low salinity water in sandstone reservoirs is examined by using contact angle measurements. Moreover, the impact of changing ionic strength on the electrokinetic charge at oil/brine interface is investigated using zeta potential technique to explain the causes of wettability alteration by low salinity water. The behavior of wettability with pressure and temperature was studied by running contact angle measurements different ranges of pressure and temperature (500-1000 psi, and 140-250°F). Sandstone rock was represented by mica sheets to eliminate the influence of rock heterogeneity and hysteresis on the contact angle measurements. Effect of salinity on wettability alteration was studied by utilizing synthetic water at a wide range of salinity (from 0 to 174,000 mg/l). In addition, two different crude oils with different compositions were used to evaluate the effect of oil characteristics on low salinity water efficiency. Zeta potential test were conducted to measure the oil/brine interface electrokinetic charge for combinations between the two crude oils, and different brines. The contact angle increased with the increase of temperature, and pressure. High salinity water showed high contact angles, while low salinity water decreased the contact angles significantly for the two types of crude oil. This proves that low salinity water could alter the wettability to more water-wet. In addition, the electrokinetic charges at oil/brine interfaces were sensitive to the change of ionic strength. Oil/brine charges were highly negative with low salinity water, which resulted in repulsion forces between oil/brine and brine/rock surfaces and altered the wettability towards water-wet. This paper demonstrates the efficiency of low salinity water in improving oil recovery by altering rock wettability, and it contributes to the understandings of the main mechanism of low salinity water.
- Europe (0.93)
- North America > United States > Texas (0.47)
- North America > United States > California (0.28)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (1.00)
- Geology > Mineral > Silicate (0.69)
Abstract For over 10 years research has been carried out on the impact of low salinity waterflooding on oil recovery. Data derived from corefloods, single well tests, and log-inject-log tests have shown that injecting low salinity water into an oil reservoir should result in a substantial increase in oil recovery in many cases. The results varied from 2 to 40% increases in waterflood efficiency depending upon the reservoir and composition of the brine. In 2005, a hydraulic unit was converted to inject low salinity brine into an Alaskan reservoir, by switching a single injection pad to low salinity water from high salinity produced water. An injector well and 2 close production wells were selected within a reasonably well constrained area. A surveillance programme was devised which included capturing produced water samples at regular intervals for ion analysis and the capturing of production data. Detailed analysis of the production data, and the chemical composition of the produced water, demonstrated an increase in oil production and provided direct field evidence of the effectiveness of LoSal™ at inter-well scales. Additionally, the response of the reservoir to low salinity water injection was confirmed by single well chemical tracer test. In parallel, laboratory studies have led to mechanistic understanding of LoSal™ in terms of multiple-component ionic exchange (MIE) between adsorbed crude oil components, cations in the insitu brine and clay mineral surfaces. The results clearly show that the enhanced oil production and associated water chemistry response was consistent with the MIE mechanism proposed. The oil production data have been modeled using an in-house developed modification to Landmark's VIP reservoir simulation package. An excellent match for the timing of the oil response was obtained which provides a good basis for predicting the result for large scale application of LoSal™ flooding. Introduction It has been more than 10 years since Yildiz and Morrow (1996) pushed forward the research started by Jadhunandan(1990; 1991; 1995) and published their paper on the influence of brine composition on oil recovery. This paper showed that changes in injection brine composition can improve recovery. Since then, Tang & Morrow (1999) have progressed the research on the impact of brine salinity on oil recovery, followed by other researchers such as Webb et al. (2004) and McGuire et al. (2005); these authors performed an extensive research programme on low salinity injection (LoSal™). This programme included numerous core flood experiments performed at ambient and reservoir conditions (at high temperature and pressure, with 'live' fluids) both in secondary and tertiary mode, single well tracer tests (SWCTT) and log inject log tests, showed a significant increase in oil recovery due to low salinity brine injection.
- Geology > Mineral (0.73)
- Geology > Geological Subdiscipline (0.48)
Abstract Low salinity waterflooding is an emerging EOR technique in which the salinity of the injected water is controlled to improve oil recovery over conventional higher salinity waterflooding. Corefloods and single well chemical tracer tests have shown that low salinity waterflooding can improve basic waterflood performance by 5 to 38%. This paper describes a model of low salinity flooding that can be used to evaluate projects, shows the implications of that model, demonstrates its use to represent corefloods and single well tests as well as field scale simulations, and gives insight into the reservoir engineering of low salinity floods. The model represents low salinity flooding using salinity dependent oil/water relative permeability functions resulting from wettability change. This is similar to other EOR modelling and conventional fractional flow theory can be adapted to describe the process in one dimension for secondary and tertiary low salinity waterflooding. This simple analysis shows that while some degree of connate water banking occurs it need not hinder the process. Because mixing of injected water with in situ water delays the attainment of low salinity, potentially preventing attainment of low salinity all together if very small slugs of low salinity water are used, care must be taken in representing mixing appropriately in interpreting data and in constructing models. The use of numerical dispersion to represent physical dispersion in 1D, radial and pattern simulations of this process is demonstrated, i.e. coarse simulations are shown to give the same result as fine grid simulations with appropriately large physical dispersion. In many applications, the fine grid simulation necessary to represent appropriate levels of dispersion is not practical and pseudoization is necessary. We demonstrate that this can be done by changing the salinity dependence and shapes of relative permeability curves. Introduction Waterflooding is widely used to improve recovery from oil reservoirs but, except to avoid formation damage, is largely designed without regard to the composition of the brine injected. Yildiz and Morrow1 showed that showed that changes in injection brine composition can improve recovery, thereby, introducing the idea that the composition of the brine could be varied to optimize waterflood recovery. Tang and Morrow2–5 built on this idea by demonstrating the benefit lowering brine salinity has on oil recovery. BP has carried out an extensive research programme on low salinity injection which has thus far included more than 20 reservoir condition core floods on a range of sandstone reservoirs from its global portfolio both in secondary and tertiary mode, more than 10 single well chemical tracer tests (SWCTT), and a log inject log test. This program has resulted in a series of publications5–8 and the registration of the LoSal™ EOR process trademark. These tests have shown improvements of the oil recovery ofwaterflood process efficiency by 5% to 38% by using low salinity water of the waterflood reserves, or corresponding reductions in residual oil saturation of 3 to 17% pore-volume. The purpose of this work is to present a simple extension to waterflood simulators that can be used to translate corefloods or SWCTT into field scale estimates of low salinity waterflood oil recovery and demonstate this with examples from a sandstone reservoir.
- North America > United States > Texas (1.00)
- Europe (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.95)
- Geology > Mineral (0.94)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
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