Study on Alkaline Flooding System with Antiscaling Effect

For scaling problem in the alkaline flooding, the alkali with anti scaling effect was researched. The results show that scale inhibition effect of PAPEMP alkaline system (containing polyamino polyether methylene phosphonae, NaOH, NaBO 2) is better than PASP alkaline system (containing sodium of polyaspartic acid, NaOH, NaBO 2), When the concentration of the PAPEMP alkaline system is larger than 4%, it could tolerate the solution with calcium ion concentration of 500mg/L without scaling; both NaBO 2 and PAPEMP alkaline system have good displacement efficiency. During the displacement process, a large differential pressure response appears when alkali concentration is high, and the incremental oil recovery increases with the increase of alkaline concentration. Microscopic mechanisms show that the alkaline solution penetrates into the crude oil and water drops are formed inside the oil phase, subsequently, to turn into the W/O emulsion, which could block the water channel and inhibit the viscous fingering, leading to the improvement of sweep efficiency.