Experimental Study On The Damage Of Reservoirs In The Conglomerate Reservoir Of QD1 Area By Weak Alkali Ternary System

ASP compound flooding was a tertiary oil recovery technology which had higher recovery efficiency than others chemical floodings. Its application had slowed down the speed of oilfield production decline and brought good economic benefit for oil fields. However, ASP compound flooding also could cause considerable damage to reservoir and bring many problems. This paper had carried out some experiments about influence that weak base ASP system on conglomerate reservoir of Xinjiang oilfield. The concrete work was as follows:Firstly, combination the rock and fluid characteristics of QD1 area conglomerate reservoir, this paper had analyzered the potential damage and reviewed the damage mechanism. Secondly, this paper had respectively studyed the compatibility about weak base sodium system, weak base ternary compound system with formation fluid by using the method of chemical and instruments such as laser granulometer, examined the carbonate scale forming rules and then studied the laws of clay swelling, siliceous scale formation, rock cuttings static corrosion. Lastly, this paper had studied the dynamic dissolution of conglomerate cores in weak base sodium system, binary system, and the ternary system.Experimental results showed that the potential physical and chemical damage caused by weak base ASP system were carbonate scale, dissolution of rock skeleton and clay mineral particles migration, clay swelling, the adsorption and retention of polymer. Polymer and surfactant could play a role in restraining the formation of carbonate scale, which particle size was smaller in weak base system than in weak base sodium system. The law of clay swelling was influenced by the concentration of alkali, polymer and surfactant, which all promoted the clay swelling in a certain extent. The polymerization of silicate was greatly influenced by pH and with the decrease of pH, the trend of polymerization was more and more serious. However, the polymer and surfactant could restrain formation of silicon scale, which was about 10%?45%. Static dissolution results showed that the consumption of carbonate ions in ASP compound system and the concentration of silicon/aluminiun ions which were dissolved were smaller than alkali system, showed that polymer and surfactant can reduce the corrosion of alkali on rock minerals. Dynamic dissolution results showed that the more concentration of alkali, the severer of damage to core, the main damage were the dissolution of rock or clay particle loss, migration and carbonate scale precipitation. The adsorption of polymer and surfactant can reduce the corrosion of alkali on rock minerals.This paper studied the damage rule about the weak base ASP system on conglomerate reservoir, which had a certain theoretical guidance for the Xinjiang oilfield.