Clean Up Water Blocking in Gas Reservoirs by Microwave Heating: Laboratory Studies

摘要

Water blocking caused by fluids invasion during drilling,rncompletion and stimulation has been suspected to reduce gasrnwell deliverability or even result in no gas productivity. Torndate, an effective method has not been reported to eliminaternsuch water blocking after many studies and trials conductedrnworldwide. In this paper, a new technique that utilizesrnmicrowave (MW) heating to clean up water blocking inrnsandstone gas reservoir was presented. First, the feasibility ofrnthis new method was discussed, and then the pilot experimentrnaimed to investigate the efficiency of water blockingrnmitigation by MW was described in details including corernsample preparation, experiment equipment, method,rnconditions, procedures as well as data analysis, etc. Next, thernresult from the experiment was also given which shows: afterrnMW heating(2450MHz, 600W, 40minutes), 1) no obviousrnchange occurred in both composition and crystal structure forrnthose samples without crystal water, while samples containedrncrystal water such as gypsum and smectite dehydrated rapidlyrnin about 2min and their microstructures have been changed; 2)rnrandom micro-fractures are likely to be induced by MWrnheating in low permeability sandstones and larger pores havernbeen produced; 3) water saturations of watered samples haverndecreased rapidly and consequently their gas deliverabilityrnincreases greatly. At last, it is concluded that water blockingrnclean up by MW heating has encouraging future in fieldrnapplication, further laboratory studies for the next phase ofrnthis project was also stated in this paper.