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坎贝盆地的北部位于古吉拉特省的梅萨那,周围有许多稠油油田,原始石油地质储量约150×106t。Balol和Santhal油田就位于这个稠油带,其API重度为15°～18°。在油藏压力9.8MPa、温度70℃时,原油黏度的范围是50～450mPa.s。黏油和水之间的高流度差导致一次采油采收率很低。后续的人工举升方式导致产水量高于产油量。因此,采用火烧油层工艺成为必然。火烧油层是在油井中点火,并注入空气维持火焰前缘。在此过程中,有一小部分地层中的原油开始燃烧,产生CO2、水蒸气和热量。它有助于降低原油黏度,从而增加原油的流动性,并驱动原油流向近井地带。印度石油天然气公司(ONGC)在梅萨那油田成功地实施了火烧油层工艺。该公司于1991年在Balol油田进行了区块试验,取得了令人满意的效果,基于此,Balol和Santhal油田于1997年开始商业规模实施火烧油层工艺。这项工艺的实施不仅赋予了这些油田新的生命,而且原油开采系数也从6%～12%提高到了39%～45%。要成功实施火烧油层工艺,需要仔细地规划和调控采油工程。根据现场经验,本文总结了实施过程中遇到的一些主要问题,这有助于今后新项目的成功规划和实施。
The northern Cambrian basin is located in Mesana, Gujarat Province, surrounded by many heavy oil fields with an original petroleum reserve of about 150 × 106t. The Balol and Santhal fields are located on this heavy oil zone with API repeatability of 15 ° to 18 °. In the reservoir pressure of 9.8MPa, the temperature of 70 ℃, the range of crude oil viscosity is 50 ~ 450mPa.s. The high flow rate difference between the viscous oil and water results in a low oil recovery. Subsequent manual lifting led to higher water production than oil production. Therefore, using the process of burning the oil layer becomes inevitable. Burning oil is ignited in the well and air is injected to maintain the flame front. During this process, a small portion of the crude oil in the formation began to burn, producing CO2, water vapor and heat. It helps to reduce the viscosity of crude oil, thereby increasing the mobility of crude oil and driving crude oil to the near-wellbore. Indian Oil and Natural Gas Corporation (ONGC) has successfully implemented a firebed process at the Mesana oilfield. The company conducted block tests in the Balol field in 1991 and achieved satisfactory results. Based on this, the Balol and Santhal fields started the commercial scale fire burning process in 1997. The implementation of this process not only gave new life to these fields, but also increased the crude oil recovery factor from 6% to 12% to 39% to 45%. Successful implementation of a firebed process requires careful planning and control of the recovery project. Based on the field experience, this article summarizes some of the major problems encountered in the implementation process, which will help the successful planning and implementation of new projects in the future.