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Collaborating Authors
Development and Evaluation of Ultra-High Temperature Resistant Preformed Particle Gels for Conformance Control in North Sea Reservoirs
Schuman, Thomas (Chemistry, Missouri University of Science and Technology, Rolla, MO 65409, USA) | Salunkhe, Buddhabhushan (Chemistry, Missouri University of Science and Technology, Rolla, MO 65409, USA) | Al Brahim, Ali (Petroleum Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA) | Bai, Baojun (Petroleum Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA)
Abstract Preformed particle gels (PPGs), a type of hydrogel, have been widely applied to control the conformance of reservoirs owing to their robust gel chemistries. Traditional PPGs are polyacrylamide-based hydrogel compositions which can withstand neither higher temperatures nor high salinity conditions. There are many deep oilfield reservoirs worldwide which demand PPG products with a long term hydrolytic and thermal stability at the temperatures of higher than 120 °C. Current PPGs neither remain hydrated nor retain polymer integrity at these temperatures. A unique high temperature-resistant hydrogel composition (HT-PPG) was developed with exceptional thermal stability for greater than 18 months in North Sea formation temperature (~130 °C) and formation water environments. HT-PPG described herein can swell up to 30 times its initial volume in brines of different salinity for North Sea. The effects of salinity and temperature on swelling, swelling rate, and rheological behavior was studied. These HT-PPGs exhibit excellent strength with storage modulus (G’) of over 3,000 Pa at the swelling ratio of 10. Thermostability evaluations were performed in North Sea brines with variable salinity at temperatures of 130 °C and 150 °C and found to be stable for 18 months with no loss of molecular integrity at the higher temperature. Laboratory core flooding tests were conducted to test its plugging efficiency to fracture. HT-PPGs showed good plugging efficiency by reducing the permeability of open fracture and did not wash out during waterflooding. Overall, HT-PPG is a novel product with excellent hydrothermal stability that make it an ideal candidate for conformance problems associated with reservoirs of high temperature and salinity conditions.
- North America > United States (1.00)
- Europe > United Kingdom > North Sea (1.00)
- Europe > Norway > North Sea (1.00)
- (4 more...)
Evaluation of a Novel Recrosslinkable Hyperbranched Preformed Particle Gel for the Conformance Control of High-Temperature Reservoirs with Fractures
Song, Tao (Missouri University of Science and Technology) | Ahdaya, Mohamed (Missouri University of Science and Technology) | Zhao, Shuda (Missouri University of Science and Technology) | Zhao, Yang (Missouri University of Science and Technology) | Schuman, Thomas (Department of Chemistry, Missouri University of Science and Technology) | Bai, Baojun (Missouri University of Science and Technology (Corresponding author))
Summary The existence of high conductivity features such as fractures, karst zones, and void space conduits can severely restrict the sweep efficiency of waterflooding or polymer flooding. Preformed particle gel (PPG), as a cost-effective technology, has been applied to control excessive water production. However, conventional PPG has limited plugging efficiency in high-temperature reservoirs with large fractures or void space conduits. After water breakthrough, gel particles can easily be washed out from the fractures because of the lack of particle-particle association and particle-rock adhesion. This paper presents a comprehensive laboratory evaluation of a novel water-swellable high-temperature resistant hyperbranched recrosslinkable PPG (HT-BRPPG) designed for North Sea high-temperature sandstone reservoirs (130°C), which can recrosslink to form a rubber-like bulk gel to plug such high conductivity features. This paper systematically evaluated the swelling kinetics, long-term thermal stability, and plugging performance of the HT-BRPPG. Bottle tests were used to test the swelling kinetic and recrosslinking behavior. High-pressure-resistant glass tubes were used to test the long-term thermal stability of the HT-BRPPG at different temperatures, and the testing lasted for more than 1 year. The plugging efficiency was evaluated by using a fractured model. Results showed that this novel HT-BRPPG could recrosslink and form a rubber-like bulky gel with temperature ranges from 80 to 130°C. The elastic modulus of the recrosslinked gel can reach up to 830 Pa with a swelling ratio (SR) of 10. In addition, the HT-BRPPG with an SR of 10 has been stable for over 15 months at 130°C. The core flooding test proved that the HT-BRPPG could efficiently plug the open fractures, and the breakthrough pressure is 388 psi/ft. Therefore, this novel HT-BRPPG could provide a solution to improve the conformance of high-temperature reservoirs with large fractures or void space conduits.
- Europe > Norway > North Sea (0.34)
- North America > United States > Oklahoma (0.29)
- North America > United States > Texas (0.28)
- (3 more...)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.93)
- Europe > United Kingdom > North Sea > Central North Sea > Utsira High > PL 006 > Ekofisk Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Tor Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Ekofisk Formation (0.99)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Conformance improvement (1.00)
A New Method for Fast Screening of Long Term Thermal Stability of Water-Soluble Polymers For Reservoir Conformance Control
Wu, Yongfu | Wang, Kang-Shi (California Inst. of Technology) | Hu, Zimeng (California Inst. of Technology) | Bai, Baojun (Missouri U of Science & Tech) | Shuler, Patrick J. (California Inst. of Technology) | Tang, Yongchun (California Inst. of Technology)
Abstract This paper presents a new convenient screening method to study the long-term thermal stability of water soluble polymers in the absence of oxygen. The polymer products are used for improved sweep efficiency by reducing the mobility ratio between injected and displaced fluids. The use of polymers as conformance control agents at low temperature and low salinity is quite common and many polymers are commercially available for this purpose. However, many reservoirs have extremely harsh conditions such as high temperature and high salinity, which are well outside the limits of many water-soluble polymer applications due to polymer degradation. There is a need for polymers that will remain stable in reservoirs with high temperature, e.g. 90 °C (194 °F) or higher and high salnity. Therefore, long-term thermal stability is critically important to such polymers used for conformance control to improve sweep efficiency. Due to the large number of polymers requiring testing and the very low level of oxygen in the reservoirs, a novel method for screening long-term thermal stability of water soluble polymers at ultra-low oxygen levels and in a time-effective manner is necessary. The thermal stability of the polymers was evaluated in terms of viscosity of their solutions in various brines containing Na, Mg and Ca cations. Viscosity measurements have been performed for a matrix of conditions of temperature and salinity. These include temperature of 90 and 120 ºC, and salinities ranging from low salinity case (TDS <3000 mg/L), to synthetic sea water (TDS ~ 35,000 mg/L), to a so-called high salinity case (TDS about 180,000 mg/L). Results show that some products at dilute concentration can create substantial initial viscosity even at temperatures as high as 90 ºC. Not surprisingly, the viscosity performance is generally much better in the low salinity brines than the higher salt brines. The better products attain a target viscosity (10~20 cp at a shear rate of several sec at 90 ºC) with polymer concentrations of less than 3,000 ppm. The best product for efficiency in creating solution viscosity differs depending on the temperature and the brine salinity. The second part of the study has been to create solutions at near zero oxygen concentrations of candidate polymer solutions in sealed ampoules. Furthermore, this near zero oxygen condition is accomplished without adding oxygen scavengers to the polymer solutions. This allows the measurement of the inherent thermal stability of the different polymers without having possibly confounding results due to the effect of any other chemical. These sealed ampoule polymer sample solutions are placed in an oven held at the test temperature (focus on 90 ºC, and some samples tested at 120 ºC) to determine any loss of solution viscosity with time. After a significant effort to fine-tune the experimental procedures, we have made such samples that reliably have a dissolved oxygen concentration of less than 10 ppb, and usually less than 5 ppb without oxygen scavengers. Results to date (some samples aged for 17 months or more) indicate polymer viscosity stability is possible for an extended period of time for some products when aged at 90 ºC. These data also demonstrate that the stability of the polymers included in this study is better in the low salinity brine than the synthetic sea water, or high salt brine. Among the many polymers screened, detailed results are presented for a representative suite of 4 different polymers. Of these, only Polymer 3 and possibly Polymer 1 demonstrate stable viscosity at 90 ºC in sea salt or high salt brine for several months or more. In the low salt brine at 90 ºC, Polymers 3 and 1 were still more stable than Polymers 2 and 4.
- North America > United States > California (0.28)
- North America > United States > Texas (0.28)
- Research Report > New Finding (0.54)
- Overview > Innovation (0.40)
A recently enacted law in Texas, which went into effect in mid-June, declares the landowner or the owner of surface rights as the holder of subsurface geothermal energy and associated resources. If the surface and mineral rights of the land have been separated, the owner of the surface estate prevails. Senate Bill 785 amended a section of the Natural Resources Code to define heat as a byproduct of geothermal energy and associated resources, but excludes mineral, oil, gas, or any product of oil or gas. It also excludes "the ownership and use of groundwater," including "minerals dissolved or otherwise contained in groundwater, including hot brines." The law entitles the owner "to drill for and produce the geothermal energy and associated resources."
- North America > United States > California (0.40)
- North America > United States > Texas (0.26)
- Energy > Renewable > Geothermal (1.00)
- Government > Regional Government > North America Government > United States Government (0.75)
The TETRA CS Neptune family of novel completion fluids are environmentally friendly, cost-effective alternatives to zinc brines (which the U.S. classifies as marine pollutants and the North Sea bans outright), or cesium formates, which replaced zinc brines in the North Sea. In this SPE Tech talk, Robert Baffoe, Operations Engineer at TETRA Technologies, explores TETRA CS Neptune fluids as monovalent and divalent brines and discusses a proven field application in the North Sea. He also reviews other formulations of this family of fluids that include reservoir drill-in fluids. Register below to watch the Tech Talk.
- Europe > United Kingdom > North Sea (0.90)
- Europe > Norway > North Sea (0.90)
- Europe > North Sea (0.90)
- (2 more...)