东海地区低孔低渗透气田完井液优化技术

针对东海地区高温、低压、低渗透油气藏常规完井液技术当前存在的问题,基于有机物高温碳化理论,用有机高分子吸水材料研制出了满足该地区完井作业的一种尺寸分布广泛的软颗粒状无(低)渗漏完井液体系,基本配方为:淡水+0.5%螯合剂YF-1+1%~2%胶凝剂SW-1+0.5%稳定剂WDJ-1。体系黏度在常温下(25~120 mPa.s)可调,与地层水配伍性好,对管材具低腐蚀性。完井液在120~130℃高温动态污染实验中可发生碳化反应,在岩心端面可生成一种致密黄、黑色黏稠状胶质暂堵层,有效地避免了工作液的滤失,岩心中黏土矿物对有机高分子吸水材料起到了一定的热催化作用。目的层岩心动态污染后,自然返排渗透率恢复率可超过90%。现场应用表明,该体系在东海地区天外天高温低渗透砂岩油气藏具有优异的保护储层效果,提高了低压产层的承压能力,极大地降低了水相圈闭损害,并促使了A7s等气井获得高产。

Technology of optimized completion fluid in low-porosity and low-permeability gas fields at the East China Sea

In order to solve the problems currently existing in conventional completion fluid technologies used at high temperature, low pressure, and low permeability reservoirs at the East China Sea area, a completion fluid system is developed based on the theory of high temperature carbonization of organic matters. This non/low filtration completion fluid system with soft particles is developed from organic high molecular water absorbing materials, with a wide grain size range. Its basic formula is fresh water + 0.5% chelant YF-1 + 1~ 2% gelling agent SW01 + 0.5% stabilizer WDJ-1. This completion fluid system has an adjustable viscosity within the range of 25 ~ 120 mPa·s at normal temperatures, being in good compatibility with formation water and low corrosive to tubulars. Carbonization can be observed during a high temperature (120 ~ 130℃) dynamic contamination experiment, a layer of viscous tight yellow and black gel is formed at the core ends, which can effectively avoid the filtration of working fluids. And the clays inside the core have thermal catalytic effects on organic high molecular water absorbing materials. And the experiment shows that the permeability recovery after flowback exceeds 90%. The field application also proves that this completion fluid system is excellent in reservoir protection when used at Tianwaitian high temperature and low permeability sandstone reservoirs at the East China Sea. The system has also improved the pressurization capability of the low pressure payzones, significantly reduced the water phase trap damage, and thus resulted in high production rates from gas wells like A7s, etc.