论文部分内容阅读
地层评价专家在通过电缆测井资料解释来评价砂岩—页岩层序中储层流体(油/气/水)的类型时一般没有多大的困难。这种评价一般是用检测象征含气带的低氢、低电子密度的综合中子—密度仪和重复地层测试器(RFT) 来完成,后者利用压力梯度和采样技术评价储层流体。然而在尼日尔三角洲,许多砂岩层均表现为其天然气的中子密度响应较弱,且重复地层测试器基本上一直都不使用。因为井眼条件差,常常导致工具被卡。而井壁取心抽提物中残余烃的油“指纹”则能为识别储层流体类型提供一种独立评价工具。我们与尼日利亚国家石油公司合作,对尼日尔三角洲西海岸Mefa油田上不同井中的井壁取心样品的溶剂抽提物作了大量的色谱分析。井壁岩心抽提物的油“指纹”清楚地展示了储层中烃的类型。油饱和砂层的“指纹”一般均以C_(15)打头,而以含气为主的砂岩抽提烃的“指纹”显示了较典型凝析气的简化烃分布模式。产水层抽提物的“指纹”显示更简化的图象,这表明较高分子量的烃没有运移到这些水层。尽管样品储臧长达3年,但这些特征还很明显且完整未缺。另外,该技术的其他应用包括对缺少现代化电缆测井数据但有井壁或常规岩心的老井的重新评价,以及对没有清晰的RFT和电缆测井响应的薄层或低渗透率砂岩进行了评价。该技术的应用遍布全世界,如美国的墨西哥湾沿岸、加拿大、印度尼西亚和巴布亚新几内亚。
Stratigraphic evaluation experts generally do not have much difficulty in assessing the type of reservoir fluids (oil / gas / water) in sandstone-shale sequences by cable logging interpretation. This evaluation is generally done using integrated neutron-densitometer and repeat formation tester (RFT), which detect low-hydrogen, low-electron density of the gas bearing bands, which evaluates reservoir fluids using pressure gradients and sampling techniques. In the Niger Delta, however, many sandstone formations show a weak neutron density response to their natural gas and the repeated formation testers are essentially not used at all. Poor borehole conditions often result in tools getting stuck. However, the “fingerprints” of residual hydrocarbon in the coring extract of the well wall can provide an independent evaluation tool for identifying reservoir fluid types. In collaboration with Nigerian National Oil Company, we conducted a large number of chromatographic analyzes of the solvent extract of wellbore coring samples in different wells in the Mefa field on the west coast of the Niger Delta. The oil “fingerprint ” of the core extract from the wellbore clearly shows the type of hydrocarbon in the reservoir. The “fingerprints” of oil-saturated sand generally begin with C_ (15), whereas the “fingerprints” of hydrocarbons extracted from gas-dominated sandstones show simplified hydrocarbon distribution patterns compared to typical condensates. The “fingerprint” of the aquifer extract shows a more simplified image, indicating that higher molecular weight hydrocarbons did not migrate to these aquifers. Although the sample is stored for up to three years, these features are still clear and intact. In addition, other applications of this technology include the reevaluation of old wells lacking modern cable log data but with wellbore or conventional core, and thin or low permeability sandstones without clear RFT and cable log responses Evaluation. The technology is used throughout the world, such as the Gulf Coast of the United States, Canada, Indonesia and Papua New Guinea.