空气钻井替换过程中防止地层损害对策

空气钻井采用空气作为循环介质，最适低压和低渗透储层的开采。由于空气钻井方法最大限度地减小了环空液柱压力，所以能获得较高的机械钻速，并且对地层无损害。但限于目前的钻井、测井、固井等一系列油、气井开发工艺技术条件以及地层条件，对采用空气作循环介质所钻的井，往往都必须把工作液（或钻井液）替入井内。在替换过程中，原来没有受到损害的地层，会因工作液中的液相和固相侵入地层，造成地层损害。而且，如果低压、低渗储

Countermeasure of Preventing Formation from Damage During Replacement Process in Air Drilling

The use of air as a circulating medium for drilling is the best way for the development of low pressure and low permeable formation. As air drilling will reduce the pressure of annulus liquid column to the smallest degree, it can acquire a greater penetration rate without any damage to the pay zones. However, because of the limitation of the drilling logging, and cementing technologies as well as the formation conditions, the well drilled by air has to be replaced by work fluid (drilling fluids). During the replacenent process, the liquid and solids in the work may invade the formation, and cause the formation damage. Furthermore, once the low pressure and low permeable formation is damaged, it is difficult to restore the primary formation permeability. on the basis of the experiments, and by using the shielding temporary plugging technique, the technical measures of preventing formation from damage during the replacement process in air drilling are put forward in this paper. the experimental results show that the temporary plugging effect is relative to the annulus fluid column pressure and plugging agent concentration in work fluid. The annulus pressure controlling method in the process of replacement discussed in thes paper is able to plug the formation in a short period, and to prevent the fluid and solids from invading the formation. The temporary plugged particles can be easily removed since they do not enter the formation deeply, and the primary formation permeability can be restored.