典型小储量气井井控技术难点及处理实践

TECHNICAL PROBLEMS AND HANDLING METHOD OF WELL-CONTROL TECHNIQUES FOR A TYPICAL GAS WELL WITH SMALL RESERVES

通过对典型小储量气井阳79井又漏又喷的处理情况分析,从储层模型着手阐述,归纳出了小储量气井在井漏后,随着漏入钻井液量的增大,而表现出地层压力不断升高和循环正常后停泵又会出现井口溢流现象的两大特征,指出了井漏、溢流、提高密度、井漏的恶性循环是处理这类井的技术难点。提出了用放喷泄压技术处理小储量气井的井控问题是经济而有效的方法,并指明了应用放喷泄压技术从安全的角度考虑应注意的主要问题:①出现又漏又喷的气井,及时诊断是否属于小储量气井对选择处理方法很重要;②针对小储量气井出现又漏又喷情况,只要满足安全条件,采取放喷泄压处理的方法是经济有效的;③含硫化氢较高,而套管或钻具的材质抗硫化氢性能差时,不宜采用放喷泄压技术。应用放喷泄压技术前需考虑井口装置、套管抗内压强度和套管鞋附近地层的破裂压力是否满足安全要求。

The activities to handle both circulation loss and blowout are analyzed for Well Yang 79-a typical gas well with small reserves. According to the reservoir model, it is summed the 2 major features of the reservoir pressure increasing constantly after circulation loss as the mud leaking volume increases and the overflow happening at the wellhead when the pump stops after circulation normal. It is pointed out the vicious circle of circulation loss-overflow-increasing density-circulation loss is the technical problem to handle this kind of wells. Applying the technique of blowout to relieve pressure is the economic and effective method to handle the well control problem for the gas wells with small reserves. Meantime, the following major issues should be paid more attention for safety to apply the technique of blowout to relieve pressure: (1) It is very important to judge whether or not a gas well is small reserves timely for choosing the handling method when both circulation loss and blowout happen; (2) When both circulation loss and blowout happen at a gas well with small reserves, under the conditions to guarantee safety, applying the method of blowout to relieve pressure is economic and effective; (3) When H2S content is high and the material performance of casing or drilling tools is poor against H2S, the technique of blowout to relieve pressure should not be used. Before applying the technique of blowout to relieve pressure, it should be considered if the wellhead devices, the internal pressure strength of casings and the formation breakdown pressure near the casing shoe meet the safety requirements.