tag:blogger.com,1999:blog-6938338130090013295.post8448497043003917619..comments2018-07-04T10:08:54.017-07:00Comments on The Petroleum System Blog: The limits of oil vs gas prediction and the relationship to migration range and charge riskThe Beta Factorhttp://www.blogger.com/profile/15140907074119678762noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-6938338130090013295.post-10534582177129509532016-04-25T06:43:36.916-07:002016-04-25T06:43:36.916-07:00Thanks for all the enthusiasm to offer such helpfu...Thanks for all the enthusiasm to offer such helpful information here however it proved to be Very helpful to me thank for sharing<br /><a href="http://www.ogknowledgeshare.com/" rel="nofollow"><b>Petroleum Training Institute Courses</b></a> | <a href="http://www.tripathlogistics.com/" rel="nofollow"><b> Drilling Engineering Courses</b></a><br /><br />Ogknowledge Sharehttps://www.blogger.com/profile/13236251277358479403noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-48799502754313861632016-01-12T21:20:53.212-08:002016-01-12T21:20:53.212-08:00No doubt that is true, and that perception will be...No doubt that is true, and that perception will be influenced by both experience and (as you have noted) by the scale of the observation. In the Vincent Field mixing model the lower perm (by only one order of mag) intervals were modelled as only 10 cm thick. It is almost independent of thickness as modelled as it is lateral continuity that is important, but in reality a thinner unit means more chance there are holes in it (less continuity). <br /><br />Not to be pedantic but 6 orders of magnitude is the difference between a million and a TRILLION ! (unless you were referring to the English "Billion"). Andrew Murrayhttps://www.blogger.com/profile/04205524696368921072noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-59532587020992797082016-01-12T07:01:28.880-08:002016-01-12T07:01:28.880-08:00I suspect different people have different percepti...I suspect different people have different perceptions of what is reasonable range of permeability and diffusivity variations. Vertically I could imagine centimeter, or millimeter scale barriers (note this is well below log resolution) down to 1 micro Darcy in most reservoirs. We just don't know the input for any of these models. <br /><br />If viscosity has a range of 3 orders of magnitude, and permeability has a range of 3 orders of magnitude, the range of rates are 6 orders of magnitude. So it could take one million years, or one billion years. <br /><br />As for flow simulations, model builders like to use average properties. That is fine for volume/storage calculations, but not for flow rates, which is limited by the end member values. So vertically the flow rate is limited by the least permeable barrier. <br />The Beta Factorhttps://www.blogger.com/profile/15140907074119678762noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-75789520505174857042016-01-12T06:51:43.931-08:002016-01-12T06:51:43.931-08:00I suspect different people have different percepti...I suspect different people have different perceptions of what is reasonable range of permeability and diffusivity variations. Vertically I could imagine centimeter, or millimeter scale barriers (note this is well below log resolution) down to 1 micro Darcy in most reservoirs. We just don't know the input for any of these models. <br /><br />If viscosity has a range of 3 orders of magnitude, and permeability has a range of 3 orders of magnitude, the range of rates are 6 orders of magnitude. So it could take one million years, or one billion years. <br /><br />As for flow simulations, model builders like to use average properties. That is fine for volume/storage calculations, but not for flow rates, which is limited by the end member values. So vertically the flow rate is limited by the least permeable barrier. <br />The Beta Factorhttps://www.blogger.com/profile/15140907074119678762noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-4610356300982395982016-01-11T22:29:34.048-08:002016-01-11T22:29:34.048-08:00Sorry, I meant "the time required for spread ...Sorry, I meant "the time required for spread of solution as through heavy oil is increased by 3 orders of magnitude.."Andrew Murrayhttps://www.blogger.com/profile/04205524696368921072noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-52340690301558746292016-01-11T21:07:27.516-08:002016-01-11T21:07:27.516-08:00Just to add to that comment: Heterogeneity in perm...Just to add to that comment: Heterogeneity in permeability - especially if laterally continuous thereby creating tortuousity in particle movement pathways - has a huge impact on mixing times, much more than the absolute perm values. For example, in the Vincent Field the spread of solution gas through a heavy oil column is increased by 3 orders of magnitude if one puts thin silty stringers at regular intervals among the otherwise multi-Darcy sand tank. These stringers are thin and only need to be one order of magnitude lower perm than the matrix to have this impact.Andrew Murrayhttps://www.blogger.com/profile/04205524696368921072noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-2206121198000745792016-01-11T21:00:56.697-08:002016-01-11T21:00:56.697-08:00Yes, using the analytical approximations in Smalle...Yes, using the analytical approximations in Smalley et al. (2004) the rate of density driven fluid pool homogenisation is a linear function of the initial density difference and permeability and an inverse function of viscosity. So we are indeed going to see large variations in the time required for GOR of an oil column reach the gravity stable condition. This does not explain all the variations between fields I referred to however. We have done these calculations using the analytical equations and also numerically modelled mixing times using the Permedia simulator. Within reasonable ranges of values for perm and viscosity we still see widely varying degrees of mixing among fields and I think this must relate to different initial states (i.e. fluid composition being "averaged" on the way into the trap, not just within the trap and post-emplacement.Andrew Murrayhttps://www.blogger.com/profile/04205524696368921072noreply@blogger.comtag:blogger.com,1999:blog-6938338130090013295.post-44458371144872562132016-01-11T05:08:14.250-08:002016-01-11T05:08:14.250-08:00Andrew, flow rates in porous media are mainly a fu...Andrew, flow rates in porous media are mainly a function of permeability and viscosity, both of which vary by several orders of magnitude, so mixing time scales should naturally vary by several orders of magnitude. In addition, we are always underestimating the degree of reservoir compartmentalization. We cannot see faults with less than 10 meter throws on seismic. We look at a well log, or a core section, what do we see in terms of permeability variation? Perhaps these can partially explain the variation in degree of mixing? The Beta Factorhttps://www.blogger.com/profile/15140907074119678762noreply@blogger.com