Abstract: Due to curved wellbore design and tubing-casing isolation by packers in horizontal gas wells,foamers are difficult to be delivered to the bottom of the wells,and large volumes of accumulated liquid in horizontal sections cannot be effectively removed.Therefore,based on the principle of synergistic foam drainage with sodium nitrite-ammonium chloride self-generated nitrogen,a split-type spherical chemical power ball was developed by mixing ammonium chloride,sodium nitrite,and a slow-release acid catalyst separately with a foamer,and fabricating them into split-type spherical balls via high-pressure stamping.A split-type chemical power ball dewatering and gas production technology for horizontal gas wells was formed;the formulation and performance of the foaming system were optimized and evaluated,construction parameters were optimized,and field tests were conducted.The results show that the basic formulation of the split-type chemical power ball foaming system(mass fraction)is 45% ammonium chloride+35% sodium nitrite+10% foamer (including foam stabilizer)+5% slow-release acid catalyst+5% high-density filler.The split-type and spherical design solves the problem of foamer placement and avoids the risk of premature reaction triggering.Each gram of reactants(45% ammonium chloride+35% sodium nitrite)can generate 108~147 mL of foam and 4.9~5.9 mL of liquid-carrying capacity.The test well exhibits pronounced slug-flow liquid unloading characteristics,the liquid production increases significantly,and the average daily gas production increases by 6.66 times.These results provide a new solution for liquid loading control in horizontal gas wells.

Key words: horizontal gas well, split-type chemical power ball, self-generated nitrogen, dewatering and gas production