干法压裂技术在实施中的经济分析

干法压裂采用了无水无伤害性液体CO₂作为挟砂剂，避免了对地层渗透率的负面影响，无需担心对地层的潜在伤害。其中CO₂在泵入过程中为液态，可以携带砂子，而在返排的过程中完全气化，不会在地层中造成水或其它化学有害物质的遗留，所以干法压裂特别适合于低渗水敏储层的开发，但是由于干法压裂过程中的费用较大，而且所用二氧化碳量大，其压裂投资大于氮气压裂和氮气泡沫压裂工艺。文章对干法压裂、氮气压裂和氮气泡沫压裂三者之间在开发低渗水敏气层时的净现值进行了比较，研究结果表明，虽然干法压裂初期投资较大，但由于干法压裂可提高通流能力，产量高，且井维护费用较低，使干法压裂比另外两者的经济性更高。从压裂完成后5年内的产量可以看出，实施干法压裂的井累积产量依然是最高的，分别为N₂气压裂、N₂泡沫压裂累积产量的2倍和4倍。

Economic Analysis of CO2/Sand Fracturing Technology for Water Sensitivity and Low-permeability Gas Reservoirs

The CO_2/sand stimulation process is a dry fracturing that uses an anhydrous, no-damage liquid, CO_2 as CO_2 is sand carrying agent, eliminating the effect on the formation permeability and potential damages,The working fluid, carbon dioxide (CO_2) is pumped as a liquid and then vaporizes at reservoir conditions, which no chemicals, gels, or water remain in the formation . So it is particularly useful for stimulating water-sensitive and low-permeability gas reservoirs. But the cost of this dry fracturing is much higher than the nitrogen fracturing and nitrogen foam fracturing because CO_2 is more expensive than the water and chemicals and the volume of CO_2 is much higher. This paper compares the net present values (NPV) of gas wells stimulated with CO_2/sand stimulation with those treated with N_2 gas stimulation and water-based stimulation(N_2 foam). The results of the study show that of the dry fracturing, CO_2/sand stimulation technology is more benefits than both N_2 gas stimulation and water-based stimulation(N_2 foam) resulting from an increase in the production by conductivity flow increase and a decrease in the maintenance in despite of its more initial costs. From the 5-year production after the fracturing, we can see the gas productions of the wells stimulated by CO_2/sand are four times those stimulated by foam and twice those completed by nitrogen.