目前长庆油田有8000余口油井的套管采用内涂层防腐技术,有效缓解了套管内腐蚀问题.为评价井下套管内涂层质量,以及套管防腐材质受井下介质影响的长期动态变化,针对井下套管内壁薄涂层(＜0.3 mm)的检测问题,研制了一种井下套管内涂层检测仪,成功测得井下套管内涂层特征曲线,实现了井下内涂层质量检测和电阻变化的定量分析,为井筒管柱防腐设计、涂层质量监控和井筒全生命周期管理决策提供依据.

To control the casing's severe CO2 inner corrosion and minimize damage to oil wells drilled into the Yan'an formation of Jurassic reservoirs; internal plastic coating was applied to the portion of the casing below the dynamic liquid level (nearly 700 m) for each of the more than 4000 wells drilled over the last 10 years. Considering the cost factor, it was not economic for the whole wellbore to have internal coating, so only the section with serious internal corrosion was internally coated with a modified epoxy-phenolic. This kind of modified epoxy-phenolic coating has excellent mechanical and anti-corrosion performance. But it’s difficult to analyze the long term aging or local mechanical damage of downhole inner coating. New approaches by electrode logging tools have been studied for monitoring the inner coating.

针对井下套管内涂层缺乏有效检测和变化监测手段的问题,创新开展微电极法和单电极法两种套管内涂层检测技术现场试验,并建立不同矿化度介质下与微电阻与内涂层损失率之间的数学模型,两种方法互补,较清晰反应出涂层套管配套情况及涂层变化趋势,为新井内防腐工艺配套执行情况核查和防腐工艺适应性评价提供有效途径.

鄂尔多斯盆地内广泛分布着厚度达数百米的洛河水层，存在多种腐蚀介质，导致早期油水井生产套管腐蚀严重，影响和制约着长庆油田油水井正常生产。2003年来在陇东老区陆续规模推广应用环氧冷缠带牺牲阳极套管外防腐和套管改性环氧酚醛喷涂热固化涂层内防腐等工艺措施，极大的缓解了套管的腐蚀损坏。通过长庆油田陇东老区防腐前后套损率对比，表明完井数年后套损率大幅降低，防腐效果非常明显。同时提出了防腐面临的新问题及应对措施，为低渗透油田井筒腐蚀防护工艺技术优化提出探索方向。

苏里格气田井间串接集输模式下,多数管道为湿气输送,管内积液量变化大且成份复杂.以某406.4 mm ×7.1 mm,长31.7 km输气干线为例,通过清管液、固形物分析,实物腐蚀测试及腐蚀软件预测评价了平均内腐蚀程度.借鉴ICDA方法,通过临界倾角计算对比查找出36处易积液段腐蚀风险点以支持开展后续监测评价.结合该两项工作基本掌握此管道内腐蚀状况,且该方法可对苏里格气田此类管道的内腐蚀评价提供一定参考.

Material testing Technical Field The present invention pertains to an anode of metal corrosion, in particular to provide a method for detection and evaluation of the remaining amount of anode aluminum outer casing of an oil well, mainly including aluminum anode downhole detection, and processing the raw data life calculation: First, a test Usui operating parameters, downhole measurements anodic aluminum outer casing; Secondly, data processing the measured values, to eliminate outliers anode, the second measured value obtained; finally, the use of anodized aluminum and the second remaining life measurements relational expression calculated an outer sleeve anodized aluminum corrosion remaining life consumption rate to achieve a downhole anodized aluminum outer sleeve is quantified judgment. This evaluation method has high accuracy, able to evaluate the effect of anti-corrosion aluminum anode online, optimization, and provide the basis for the safety assessment of corrosion casing design, with the value of the wellbore early warning management of production safety.

The present invention belongs to the field of detecting anti-corrosion coating, a single electrode current detection method of downhole oil casing inner coating, the lower the positive electrode and the auxiliary supporting equipment in the oil casing string, through the positive electrode at a constant voltage, lifting the tool string downhole current from the positive electrode, the electrolyte, the coating composition and the ground electrode breakage during acquisition circuit, the current reflects the quality of the oil casing coating. The present invention provides a downhole oil single electrode current detection method of coating the inner sleeve may have conductive medium where the oil, water and the like in oil wells, processing and interpretation of the data collected, to achieve coated casing downhole oil layer accurate qualitative and quantitative determination of the determination, with good accuracy, fast logging, easy and safe operation, low cost detector.

The invention belongs to the field of corrosion-resistant coating detection and provides a single-electrode current type detection method of a downhole oil casing inner coating. A positive electrode and an assistant and matched instrument string are lowered into an oil casing, constant voltage is fed to the positive electrode, the instrument string collects current of a circuit composed of the positive electrode, electrolyte, a broken position of the coating and a grounding electrode in the process of being lifted from the bottom of a well, and the current reflects quality of the coating in the oil casing. By the single-electrode current type detection method, the oil casing inner coating in the well can be qualitatively and quantitatively judged accurately by processing and explaining collected data under the circumstance that conductive media like oil and water exist in an oil-water well; the single-electrode current type detection method is higher in accuracy, quick in well logging, convenient and safe to operate and low in detection cost.

Casing corrosion damage was a main technical difficult problem affecting the normal exploitation of Longdong oil area for a long time. In allusion to the exploitation and corrosion fact of this oil area, the cold epoxyn-bond trap plus zinc anode technology suited for casing protection in Xifeng Oilfield of Longdong oil area was expatiated. Through application of this technology in the domestic equipped oilfield for the first time, the effect and benefit obtained were evaluated, it was worth popularizing and applying.

近20年来,在国内外H2S/CO2共存环境、高含Cl-的深井或复杂水平井中,为保障井筒寿命并控制耐蚀合金管柱成本,超级13Cr不锈钢油套管的应用逐步增多,而ISO等标准中对于超级13Cr油套管的适用条件规定严格,特别是在超级13Cr的抗硫化物应力开裂影响因素方面,不同学者研究认识不统一.为此,模拟陕北某区块含H2S气井腐蚀环境,利用电化学系统和高压腐蚀测试系统,评价了超级13Cr油套管的电化学和抗硫化物应力开裂能力.结果表明,在模拟环境下的超级13Cr电化学腐蚀速率为0.01mm/a,而传统13Cr的腐蚀速率为0.26 mm/a.同时在抗硫化物应力开裂试验中,加载80％ AYS和90％ AYS下的超级13Cr没有出现NACE标准溶液试验下的开裂问题.该结果为类似气井环境下的超级13Cr应用提供了一定的参考.

Over the past two decades, Super 13Cr (Super Martensitic Stainless Steel) tubing and casing have been widely applied for the equilibrium of a gas well's lifetime and tubular goods inputs in the H2S/CO2 coexistence environment or high Cl- deep wells or complex horizontal wells, However, the application conditions for Super 13Cr steel are strictly limited in the description of the international standards like ISO; especially concerning its resistance to sulfide stress cracking (SSC) and the related influencing factors, different scholars always dispute with each other. In view of this, simulating the corrosion environment of a H2S gas well in a block in north Shaanxi province, China, we conducted laboratory tests to evaluate the resistance of Super 13Cr tubular goods to electrochemical corrosion and SSC by using the electrochemical system and high-pressure corrosion testing system. Under such simulated corrosion environment, the electrochemical corrosion rate of Super 13Cr steel was 0. 01 mm/a, while that of the conventional 13Cr steel was 0. 26 mm/a; unlike that in the NACE's standard solution test, there is no SSC sensitivity found when the test pressure reached 80% or 90% of AYS (Applied Yielding Strength). This study provides reference for the application of Super 13Cr tubular goods in such a similar sour downhole environment.

For outer corrosion of casing of single or double well cluster in loess plateau area,the CP technology of outdoor removable deep well anodic in Changqing Oilfield was tested.When the CP system operating voltage of the composite anode of MMO and silicon cast iron was less than 16 V and the anodic well depth was more than 200 m,the depth of casings protected was more than 1 400 m and the MMO anode was removable.This technology offers an economic and suitable way to protect the casings of complete single or double well clusters in the oilfield similar to that in loess plateau area.

油水井套管腐蚀破损一直是严重困扰长庆油田正常生产的技术难题。该油田通过多年艰苦探索和实践,在油田套管腐蚀方面取得了重要的认识突破,形成了适合长庆环境特点的两项套管外防腐主体工艺技术和二项内防腐技术,积累了套损井防治的经验。套管防腐技术的大量应用,为油田大发展提供了技术保障。

Some annular oil well pipes of PetroChina Changqing Oil Field Company suffered from severe corrosion. The main performances of the internal DPC coating are studied, which show that the coating can effectively control the internal corrosion. The application process is proposed and coating has been successfully applied in 35 oil wells.

自长庆靖边气田大规模开发以来,气井井筒的腐蚀和防腐工艺一直是采气工艺中的重要问题.通过对几种腐蚀预测模型的分析,结合长庆气田腐蚀现状,将引进的腐蚀预测软件技术与同一气井不同段、多口井特定段失重挂片和措施井起出油管柱进行腐蚀分析对比,验证预测的可行性和不足处.在实践基础上探讨了在缓蚀剂加注方式和制度方面研究的一些结论和存在的问题.最后提出了靖边气田井筒防腐的几个针对性研究方向.