准噶尔盆地超稠油成因及开发对策

Origin of Super Heavy Oil in Junggar Basin and Development Strategy

准噶尔盆地西缘的春风油田是一个"油层薄、地温低、黏度大"的超稠油油田,应用常规蒸汽吞吐工艺时井筒、地层热损失大,蒸汽热波及范围小,直井蒸汽吞吐无法突破产能关。文章研究了春风油田超稠油的形成机理,指出沙湾组原油遭受过强烈的生物降解作用,油藏温度仅为26℃,对应原油黏度为70000mPa·s,60℃条件下稠油转变成牛顿流体。稠油中的沥青质相对分子质量大、极性强,原油中C+H含量达到95%以上,杂原子含量较低,加热时,烃类裂解需要的能量较低,胶质与沥青质之和低于20%,较容易降黏。以此油田物性分析为基础,提出了适合该油田特点的开发方案,发展了水平井+蒸汽吞吐+注氮气+注油溶性降黏剂的集成技术,实现了油田高速高效开发,建成年产61×104t原油的能力,采油速度为3.0%。截至2013年3月,HDNS技术已在春风油田257口井应用,均获得成功,累计增油65.4×104t。

Chunfeng Oilfield on the western periphery of Junggar Basin is a super heavy oil field with 'thin oil layer, low ground temperature and high viscosity.' If conventional steam stimulation technology is used, a lot of heat will be lost in the wellbore and the ground with steam heat limited in a small scope. Steam stimulation of straight well cannot make a breakthrough in productivity. This article studies the genesis mechanism of super heavy oil in Chunfeng Oilfield, pointing out that crude oil from Shawan formation came under strong biodegradation. The temperature of oil reservoir is only 26℃ with the crude viscosity 70000mPa·s. Under the condition of 60℃, heavy oil turns into Newtonian fluid. Asphaltene in heavy oil is relatively high in molecular quality and strong in polarity. The C+H content in crude oil exceeds 95 percent while the impure atom content is relatively low. Cracking of hydrocarbons, when heated, calls for relatively low energy with the total of gum and asphaltene is lower than 20 percent, easy to reduce the viscosity. Based on this analysis of physical properties of the oil field, a development plan suitable for the characteristics of the oil field was formulated while the integrated technology, such as the horizontal well+steam stimulation+injection of nitrogen+injection of oil insoluble viscosity reducer, was developed for high-efficiency oilfield development. An annual crude oil productivity of 610,000 tons was constructed at a 3.0 percent oil production rate. As of March 2013, the HDNS technology has been successfully used for 257 wells of Chunfeng Oilfield with the additional oil output accumulated to 654,000 tons.