Comprehensive Research On Acidification And Plugging Technology In Nanpu Oilfield

The Nanpu oilfield regional structure belongs to the Nanpu Depression in the northern part of the Huanghua Depression of the Bohai Bay Basin.It mainly develops five structures,such as Nanpu 1,Nanpu 2,Nanpu 3,Nanpu 4 and Nanpu 5,and includes Nm,Ng,Ed 1,Ed2,Ed3,Esl,Es2+3 and 0 eight sets of oil-bearing systems.Industrial oil streams have been obtained at Nm,Ng,Edl,Ed3 and 0.Nanpu 1,Nanpu 2,Nanpu 3,Nanpu 4,Nm,Ng,Ed reservoir are the Jidong Oilfield independent exploration and development blocks.The Dongying Formation in Nanpu Oilfield is complete and the main lithology is gray-dark gray mudstone and sandstone,and the gravel sandstone is not equal.According to its characteristics of the cycle can be divided into the eastern section,the second and third section of the East.Edl in the development process,the energy decline faster,the wells in the workover during the work of a large number of wells into the reservoir leakage of oil pollution,resulting in pollution wells and wells after the low volume,need to plug to restore normal production.Because the reservoir water sensitivity index and salt sensitivity index are high,the reservoir is unavoidably polluted during the injection of different injected water(well water,sea water and sewage),and the acidizing and increasing process is needed to improve the water absorption capacity.Therefore,it is necessary to study the cause of plugging,plugging mechanism and acidizing plugging technology in the eastern section of Nanpu oilfield.In this paper,the reason of acid sensitivity mechanism is proved,and the reason of strong acidity of Edl core in Nanpu oilfield is clarified.First,the excessive dissolution of high concentration acid solution makes the core skeleton damage serious,causing the internal particles to move and clog the seepage channel.Second,the high concentration of HF and the core of the reaction,resulting in a certain amount of secondary precipitation,mainly including calcium fluoride and fluorosilicic acid or aluminum aluminate precipitation,blocking the formation.Which the impact of iron precipitation is limited.Based on the analysis of the damage mechanism of sandstone reservoir,the type of damage and the potential damage factors of reservoirs,the acid liquid formula system of Ed1 sandstone reservoir in Nanpu Oilfield was formed by the screening test of acid and its additives.Acidification of the implementation of the program and supporting technology,and ultimately developed for the Nanpu oilfield carbonate rock acidification(pressure)to increase production of the initial technical program.