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Некорректность определения Pн(Кв)
bne: Рассмотрение данных лабораторных исследований показывает, что зависимости Pн(Кв) как правило заментно ниже чем Pп(Кп) и идут почти без разброса Кроме того зависимости от Кв и Кво обычно близки или совпадают По частному сообщению Венера Мамяшева в этом случае нередко очень велика анизотропия сопротивления (что отвечает модели при которой пленки воды вытянуты вдоль направления вытеснения и меньше представлены в поперечном направлении) Есть подозрение, что причиной этого является неравновесный характер распределения воды в порах при таких определениях Это приводит к систематике, которую можно пытаться устранять только за счет усложнения и удорожания эксперимента (в частности обработки ультразвуком для искусственного старения распределения воды) Тема очень важная и практически (подсчет запасов!) и потому выделна в отдельный топик
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bne: SCA2005-10 1/12 WETTABILITY ALTERATION DURING AGING: THE APPLICATION OF NMR TO MONITOR FLUID REDISTRIBUTION S.H. Al-Mahrooqi, C.A. Grattoni, A. H. Muggeridge and X.D. Jing Petroleum Development of Oman (PDO), Muscat, Sultanate of Oman Department of Earth Science and Engineering, Imperial College London, SW7 2AZ Currently with Shell Representative Office Oman and JVR Centre for Carbonate Studies, Sultan Qaboos University This paper was prepared for presentation at the International Symposium of the Society of Core Analysts held in Toronto, Canada, 21-25 August 2005 ABSTRACT The changes occurring during aging of reservoir core samples in crude oil, which aims to restore the reservoir wettability, are complex. The dynamic mechanisms involved are still not entirely clear. Understanding the dynamics of wettability restoration in the laboratory will improve our ability to reproduce reservoir conditions before performing core tests and help to ensure that laboratory data are representative of the reservoir. This paper investigates the changes of fluid distribution occurring at the pore-scale during wettability restoration using a combination of NMR T2 relaxation data and electrical impedance measurements. Sandstone core plugs were aged in crude oil at various conditions. One sample was aged at atmospheric pressure and a temperature of 35 to 50° C, for more than 100 days while two other plugs were first aged at ambient conditions for 80 days and then at 85° C and 1.38 MPa for 50 more days. NMR relaxation and electrical measurements were performed on all the plugs at regular time intervals during aging. In addition, the Amott-Harvey wettability index was measured on clean and aged cores. The T2 distributions as a function of aging time clearly show changes in oil/water configuration at the pore scale. We infer that this can only be due to wettability changes resulting from interactions between the crude oil and the rock surface. Both NMR data and electrical measurements show that wettability alteration can occur before the 40 days traditionally used in the majority of studies, even at room temperature and pressure. These experiments demonstrate the ability of NMR to identify wettability changes and, under certain conditions, to infer the fluid distributions at pore level.
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