Method Research Of Combining In-depth Huff And Puff With Plugging In Horizontal Wells Of High-temperature And High-salinity Reservoirs

This paper takes the main oil layer of HD4CIII of Hadson Oilfield as the theme to study.In view of two world-level difficult problems of the difficult conditions of high temperature?115°C?,high salinity?26.9×10⁴mg/L?and high calcium and magnesium ions?2.02×10⁴mg/L?in Hadson Oilfield and water shutoff in horizontal wells,the methods of physical simulation experiment are used to study the stabilizing oil production and controlling the water in horizontal wells of high-temperature and high-salinity reservoirs systematically.Aiming at the special requirements of the high temperature,high salinity and high calcium and magnesium ion conditions in the Hadson Oilfield,plugging agents of DCA microspheres,flexible microspheres and cationic microspheres were synthesized in order to solve the contradiction between the injection and the ability of deep plugging.The formulation and process of DCA microspheres were optimized.Nanometer and micron DCA microspheres were produced by emulsion polymerization using very safe water instead of ethanol as solvent.By changing the amount of acrylamide monomer,the change of hydrophilic and self-aggregation properties of DCA microspheres was carried out.DCA microspheres had the self-aggregation.In the simulated formation water containing 20000mg/L of calcium ions,DCA microspheres began to appear in order after 8.5 hours to form larger“microspheres cluster”.The particle size of DCA microspheres can be controlled from 200 nm to 10²?m by changing the amount of A agent in the oil phase.The industrial production of microspheres was realized to meet the needs of pilot testing.The basic performance of three kinds of microspheres was systematically evaluated.DCA microspheres were placed at 115°C for 180 days and 150°C for 103 days.The microstructure did not degrade with good high temperature thermal stability.The longer the microsphere material was placed at the reservoir temperature,the higher the plugging strength of the pore and the throat.It can be seen that the three kinds of microspheres can be injected into the deep layer of the reservoir by the micrographs of the microspheres from the outlet of the core and the scanning electron microscopy at different positions of the core.The total amount of microspheres used to plug the three types of microspheres were less than 10^-3PV of the water channel.The injection capacities of the three types of microspheres were evaluated by the resistance coefficient at the injection end of the core and the distribution of the resistance coefficient and were not ideal.The“pollution”of the plugging of the inlet end was serious.The technical idea of in situ polymerized DCA?ISP-DCA?microspheres was proposed.The residual resistance coefficient of 0-5cm and the residual resistance coefficient along the core were taken as an index.The three types of microspheres were used to control the water channel.The order of plugging ability of three types of microspheres to the water channel was DCA microspheres,cationic microspheres and flexible microspheres.The residual resistance non-uniformity coefficient of three kinds of microspheres was greater than 1.The injection end were more serious pollution.The system of improved ISP-DCA microsphere had more good injection.The residual resistance non-uniformity coefficient was less than 1.There was almost no“pollution”at the injection end.The ISP-DCA microspheres had a stable plugging capacity along the core and the property of scour resistance.The bottleneck technology of high-temperature emulsification performance evaluation was overcome and high-temperature emulsification dynamic tester was improved and produced.The evaluation index of emulsifying capacity of oil and water was established and was the emulsification coefficient EI.The evaluation index of emulsion stability was established and was half-life(t_1/2).At the same time,the test method of high temperature emulsification dynamic tester was put forward.Under the condition of high-temperature and high-salinity reservoirs,the emulsification coefficient EI of the emulsifier HA was 0.783.In order to challenge the temperature limit and the temperature was 130°C,the emulsifier HA still had good emulsifying ability.The emulsifier HA had a good injection in the water flow channel of the reservoir.The HA,HA-I,RA-B,and RA-WT of the emulsifier had the potential to be used in the in situ emulsification of the Hadson Oilfield.In order to achieve the in situ emulsification in the reservoir,improving the emulsifying capacity of surfactant solution and crude oil was more important than interfacial tension and emulsion stability.The remaining oil saturation,the injection rate and the permeability were the main factors that affected the in situ emulsification of the emulsifier in the reservoir.As long as the injected emulsifier RA-WT was in full contact with the remaining oil in the reservoir,the emulsifier with strong emulsifying ability could form emulsion with crude oil under the disturbance conditions of its migration and reach the high resistance coefficient.After the core was saturated with oil and was followed by emulsifier flooding.The maximum resistance coefficient along the core was 75.In order to resolve the contradiction between avoiding pollution in production wells and expanding the plugging area,the technical direction of stabilizing oil production and controlling the water is combining in-depth huff and puff with plugging in horizontal wells of high-temperature and high-salinity reservoirs.The simulation device of the high temperature and high pressure was developed in horizontal wells.The effect of increasing oil production and decreasing water cut was obvious with temporarily plugging of emulsifier.The effective range of water shutoff was expanded by temporarily plugging of emulsifier.The maximum value of enhanced oil recovery was 24.88%by combining carbon dioxide in-depth huff and puff with auxiliary plugging of strong emulsifier slug and plugging of ISP-DCA microsphere slug.It was recommended that this technology should be the technical direction of the priority development of the horizontal wells in the Hadson Oilfield for controlling water cut and increasing oil recovery.The program of pilot testing was completed on combining in-depth huff and puff with plugging in horizontal wells of high-temperature and high-salinity reservoirs.