富液页岩中挥发油和凝析气产量分析

Advances in Geo-Energy Research, 2019, 3(1): 29-42

原文网址: http://www.astp-agr.com/index.php/Index/Index/detail?id=91  

       近年来，从致密层（页岩）开采出来的液体烃类产量增长明显。在液体烃类（石油和凝析油）开采期间，大量的相关气体也被产出。挖一口井的经济可行性取决于能够保持合理的液体比例。在美国，比如德克萨斯州伊格福特、科罗拉多怀俄明奈厄布拉勒和北达科塔的巴肯，液体储层的成分和状态对从致密层或页岩中开采液体烃类十分重要。储层临界温度上一点点偏差可以改变液体的状态（挥发油或者凝析油），进而导致液体产量受到影响。最近，美国犹他大学的Palash Panja等人研究了液体（挥发油或者凝析油）的影响、储层渗透率、最终采收的操作条件和产出的气体-液体比例。在他们的论文中，从低到高的液体烃类，选取五个不同液体储层。最富足的液体储层（液体5）的渗透率是100mD，相对于1000psia，当在3000psia井中操作时，十年间凝析油的产量增加了2%。相同条件下，在匮乏的液体（液体1）储层中，十年间凝析油的产量增加了9.3%。因此，在低渗透性（100mD）储层中井底压力更高时操作能使挥发油或者凝析油能是液体的采收最大化。然而，在高渗透性储层中，更低的操作压力能更好的增加采收效果。最后，井底压力对富液高渗透性储层有很小的影响。在高于3000psia压力下操作抑制了气体的产生，相对提高了液体的产量。相对于渗透率为1000mD井底压力为1000psia的储层，100mD渗透率储层中液气比下降的更快。高断裂渗透率（1000mD或者更高）对更高井底压力的液体采收产生不好的影响，导致采收的产量减少2%。最佳断裂渗透率应该基于储层渗透率、操作压力和液体类型。

Productions of volatile oil and gas-condensate from liquid rich shales

Palash Panja, Manas Pathak, Milind Deo

(Published: 2018-09-05)

CorrespondingAuthor and Email: 

Palash Panja, ppanja@egi.utah.edu; ORCID: https://orcid.org/0000-0002-0631-9907

Citation: Panja, P., Pathak, M., Deo, M. Productions of volatile oil and gas-condensate from liquid rich shales. Advances in Geo-Energy Research, 2019, 3(1): 29-42, doi: 10.26804/ager.2019.01.02.

ArticleType: Original article

Abstract：

   The growth in productions of liquid hydrocarbons from tight formations (shales) has been phenomenal in recent years. During the production of liquids (oil and condensate), large amounts of associated gas are also produced. The economic viability of a producing well depends on maintaining a reasonable proportion of liquid. The compositions and state of reservoir fluid play an important role in producing liquids from tight formations or shales in the USA such as Eagle Ford in Texas, Niobrara in Wyoming-Colorado, and Bakken in North Dakota. Small deviation in reservoir temperature around the critical point changes the state of the fluid (volatile oil or condensate) and as a result, the production of liquid is affected. Impacts of the state of the fluid (volatile oil or condensate), reservoir permeability and operating conditions on ultimate recoveries and produced gas liquid ratio are studied here. Five different reservoir fluids representing low to high liquid hydrocarbon contents are considered. Around 2% increment in condensate recovery after 10 years of production is observed from 100 nD permeability reservoir filled with the richest fluid (fluid 5) when the well is operated at 3000 psia compared to 1000 psia. At the same conditions, 9.3% more condensate is recovered for the leanest fluid (fluid 1). Therefore, operating the well at higher flowing bottom hole pressure (BHP) maximized the liquid recoveries of volatile oils and condensates in case of low permeability reservoirs (100 nD). However, in case of higher permeability (1000 nD) reservoir, lower operating pressure was preferable to increase the recovery. Conclusively, bottom hole pressure has less impact on the richer fluids and higher permeability reservoir. Operating well at higher BHP (3000 psia) also suppresses the production of gas and relatively enhances the production of liquid. Liquid to gas ratio (LGR) declines more rapidly for 100 nD permeability reservoirs compared to 1000 nD at BHP of 1000 psia. High fracture permeability (1000mD and above) appeared to negatively affect liquid recoveries at higher BHP resulting in reduction of recovery by around 2%. An optimum fracture permeability may be necessary based on reservoir permeability, operating pressure and type of fluid.

Keywords: Volatile oil, gas-condensate, critical temperature, liquid recovery, production optimization.

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