Petrophysical analysis case studies. Fluid identification and characterization. Layer thickness evaluation. Help with editing Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment.
Houston: Baker Atlas, originally published by Western Atlas. Also in WBM-drilled wells, tar intervals can be defined by those depths over which the shallow- and deep-reading resistivity tools show a lack of oil-saturation change, which indicates that the hydrocarbons in the pore space are too viscous to be displaced by the WBM filtrate.
If the reservoir is not too shaly, neutron logs can be one of the keys to identifying gas-bearing intervals. The best data from which to determine FWL fluid contacts are given by wireline formation tester tools that measure pressure at discrete depths over reservoir intervals.
When adequate data can be collected, the fluid contacts can be determined very accurately by identifying the depths at which the characteristic pressure gradients change. See the page reservoir pressure and temperature along with associated pages for additional information on fluid-contact depth determination using pressure information.
Overall, the formation-pressure-survey data should be the primary source of data for defining the FWL fluid contacts. During waterflooding, these forces may act together with frictional forces to resist the flow of oil. It is therefore advantageous to gain an understanding of the nature of these capillary forces.
Definition : Capillary pressure is the pressure difference existing across the interface separating two immiscible fluids. If the wettability of the system is known, then the capillary pressure will always be positive if it is defined as the difference between the pressures in the non-wetting and wetting phases. That is:. Thus for an oil-water system water wet.
For a gas-oil system oil-wet. Capillary pressure is as a result of the interfacial tension existing at the interface separating two immiscible fluids. The interfacial tension itself is caused by the imbalance in the molecular forces of attraction experienced by the molecules at the surface as shown below. For molecules in the interior:. For molecules on the surface:. The net effect of the interfacial tension is to try to minimize the interfacial area in a manner analogous to the tension in a stretched membrane.
To balance these forces and to keep the interface in equilibrium, the pressure inside the interface needs to be higher than that on the outside. The effect of interfacial tension is to compress the non-wetting phase relative to the wetting phase. The force created by the internal pressure is balancing it. Since the interface is in equilibrium, force can be balanced on any segment.
The interfacial forces are eliminated by taking as a free body, that part of the interface not in direct contact with the solid. A force balance would give:. And since by definition , , we have:. For an air-water system, the air is the non-wetting phase and.
This equation is referred to as Laplace 's Equation in some texts. Oil-water system. Since , then,. That is,. Cgs Units:. Field Units:. While a preferred embodiment of the present invention has been illustrated in detail, it is apparent that modifications and adaptations of the preferred embodiment will occur to those skilled in the art.
However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present invention as set forth in the following claims. All rights reserved. A SumoBrain Solutions Company. Login Sign up. Search Expert Search Quick Search. United States Patent Such contact level may be estimated without actual capillary pressure measurements. The method relies on a worldwide correlation of permeability and porosity to a function of capillary pressure.
The constants set forth in equations b and c above may be adjusted to fit measured data from rock samples within the reservoir. Harris, Thomas G. Houston, TX. Click for automatic bibliography generation. Restech, Inc. Journal of Petroleum Technology--Thomeer, J. JPT, Swanson, B. World Oil--Smith, D. Guests Have Restricted Access. Crain , P. Eng in This webpage version is the copyrighted intellectual property of the author.
Do not copy or distribute in any form without explicit permission. Identifying Fluid Contacts Gravity segregation of fluids puts gas on top of oil or water and oil on top of water in most reservoirs. The top of the transition zone is the base of clean oil production. The base of the transition zone is the top of free water. The length of the transition zone depends on the permeability of the rock - lower permeability gives longer transition zones.
Your donation is guaranteed to directly contribute to Africans sharing their research output with a global readership.You must log in to edit PetroWiki. Help with editing. Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. Free water level and oil water contact information. These depths need to be defined in every wellbore, free water level and oil water contact the extent that they occur. These are listed approximately in free water level and oil water contact order in which these data are gathered from a wellbore. Each has its own strengths and weaknesses. Each is an independent source of information; therefore, the most accurate fluid contact is obtained by using all of the data available for a particular well. The first step in using any and all of these data levvel is to align their depths as accurately as possible. Mud logs record mud gas compositions and quantities and descriptions and analyses of drill cuttings. These provide free water level and oil water contact about the fluid content and lithology of the rock as it is drilled. These data have some depth uncertainty because of the lag time between a rock interval being drilled and the time wxter cuttings are recovered at the surface. The field personnel work to minimize this uncertainty by periodically dropping a bit of "carbide" into the drilling mud and then determining how long it takes for it comment envoyer un email chez free show up on the mud-returns free water level and oil water contact output. The mud log gas-analysis data plotted vs. It can game of thrones season 3 episode 7 project free tv used to determine a GWC or OWC because the background gas content per unit volume of aquifer brine is so low compared with that of free gas or gas dissolved in oil. The methane-concentration log is most useful for defining the top of free water level and oil water contact reservoir and the GWC for a gas reservoir, and the detailed gas analyses can also identify a GOC from increasing ratios of the heavier hydrocarbon components compared with methane as depth increases. Direct observation of oil staining, and yellow conact brown ultraviolet UV fluorescence on drill cuttings, identifies oil. When drill cuttings are crushed in solvents, mobile oil migrates to the solvent, which then fluoresces. Defining the depths of the fluid contacts, gas/water contact (GWC), oil/water the depth of the OWC or GWC, or more particularly the related free water level. free water level (FWL) correctly and to understand the uncertainties and (often the cause of a difference of the oil-water contact (OWC)/ GWC, and not faults. determination of the free water level (FWL, level at which gas-brine capillary pressure is zero). ) Laboratory and reservoir interfacial tension and contact angle. Because there is no oil with surface active agents and little organic matter. In compliance with European Union (EU) legislation for visitors from the EU, Schlumberger requests your permission to place cookies on your computer to both. Sw so that at each height you can determine water saturation. keeping in mind and large differences between the free water level and the oil water contact are. free water level defined by the displacement pressure. Thus, in reservoirs, the oil/water contact (OWC) is above the free water level (FWL). Hence, if we have a. An estimate of oil-water contact (OWC) and the understanding of the capillary behaviour of hydrocarbon reservoirs are vital for optimum reservoir characterization. For the water saturation (Sw) calculations, the depth of the OWC or GWC, or more particularly the related free water level (FWL), is a required These characteristics assist in identifying oil and gas reservoirs, the top of the. From Wikipedia, the free encyclopedia. Jump to navigation Jump to search. In the hydrocarbon industry water contact is the elevation above which fluids other than water can be found in the pores of a rock. For example, in a traditional hand-excavated water well, the level at which the. A method for predicting the hydrocarbon/water contact level for oil and For determining, the free-water level or height in a well, the present. The model may be improved from actual capillary pressure data to adjust the constants in equations 9 and 10 as the data becomes available. In gas filled dolomite reservoirs, this is the only way to see the gas crossover - such log displays can be made in the field on the logging truck if you suspect gas and dolomite might be present. Air permeability ranges from low at Lake Creek field and Stratton field to high in the other four sandstone reservoirs. Photo of Ted Cruz on a plane with no mask goes viral. This geology article is a stub. The best way to look for crossover in these cases is to create shale corrected logs, rescaled for the density of the minerals in the zones and display these curves on depth plots. At each depth level, the four observed variables are 1 depth, 2 porosity, 3 water saturation, and 4 air permeability. This contact level should be determined to locate delineation wells, plan development drilling, and forecast reserves and economics, especially when operating in high-cost areas. It does not however mean that you cannot produce oil below the contact it will just have too much water relative to the oil. In poorly porous intervals, the oil-water, gas-water or gas-oil contacts can similarly be obscured, which makes estimation of hydrocarbon reserves difficult. Welcome To C rain's P etrophysical H andbook. Miocene oil Log, side wall cores, Well cut water after 3 months Offshore Louisiana pressure buildup Unnamed Discovery well 11 16 Highest known water on log. Guests Have Restricted Access. All Rights Reserved.