高含硫环空带压井液面监测技术

MONITORING TECHNIQUE OF THE LIQUID LEVEL FOR THE WELL WITH HIGH SULFUR AND HIGH PRESSURE IN THE ANNULUS

普光气田高含硫化氢、二氧化碳,腐蚀环境恶劣,对井筒完整性技术要求高。气井主要采用"井下安全阀+循环滑套+永久式封隔器+坐落短节"一体化高抗硫材质管柱,永久式油套环空加注保护液确保井筒完整性。在生产过程中部分井环空带压套压达到35 MPa,且环空中渗漏有H2S,严重影响井筒安全,需准确测取环空液面,以便及时补充加注环空保护液。现有国产气液界面监测仪材质不抗硫化氢、仪器整体耐压低、变通径声波衰减快、测试精度差,同时也缺乏配套的测试工艺,无法探测带压井环空液面。针对这一难题,研制了高抗H_2S、耐压40 MPa的高精度液面测试仪,配套形成了高含硫环空带压井液面监测工艺,成功应用于普光多口高含硫环空带压井液面监测,并拓展解决了小井眼(套管直径10.16 cm)抽油井环空液面无法准确测取的难题,为高含硫气井环空保护液加注和小井眼抽油井合理工作制度制定提供了依据。

Puguang Gasfield is characterized by high hydrogen sulfide and middle carbon dioxide,because of the rather serious corrosive environment,the technical requirement in the borehole completeness or integrality is pretty high. The completeness of the gas well is ensured mainly by the integrated pipe string with high-anti sulfide material quality,permanent string-casing annulus injected by the protecting liquid,the former is composed of downhole safety valve,circling sliding sleeve,permanent packer and seating pup joint. In the process of the production,the casing pressure of the partial annulus can reach 35 MPa,and moreover H2S is leaked in the annulus,thus the borehole safety is seriously influenced,so it is needed to accurately measure the annular liquid level so as to add the protecting liquid in time. At present,the home-made gas-liquid level monitoring instrument cannot resist hydrogen sulfide,the complete pressure resistance of the instrument is rather lower,the sonic attenuation of the alternative path logging unit is rather fast,the test precision is rather lower,and furthermore the matched testing technology is absent,so the liquid level cannot be measured for the wells with high pressure. In the light of the problems stated above,the high-precision liquid-level testing instrument with high H2S resistance and 40 MPa pressure resistancewas developed,and moreover matched into the liquid level testing technology for the wells with high pressure and high-sulfide annular belt. The technology was applied successfully in many wells of the gasfield,and furthermore expanded and solved the problem that has no way to accurate measure the annular liquid level for the slim-hole oil pumping wells,thus the evidences have provided for the injection of the annular protecting liquid for the high-sulfur gas wells and establishment of the reasonable operation system for the slim-hole oil pumping wells.