gas in the elang-plover, gas in sandstone abov, page-84

Ort,

First of all thanks for your kind post and acknowledgement yesterday. It was most appreciated.

I thought that I would add some comments regarding reservoir development, porosity, gas shows and logs which you and many others have raised in relation to HS-1 drilling. I have attached Ort's post in full below.

Before I go on however, I have found it rather mystifying why MEO hasn't been more informative about the well and what it might mean in a structural sense and for the overall prospect. They have provided only the barest amount of information from drilling reports - and then sometimes that has not been accurate (i.e. their first call on the top of the Elang/Plover reservoir which later had to be amended). We have relied on informal summaries and explanatory figures from such people as Dr Daz to inform us and tell us what is happening (as other correspondents have also noted).

Yes you are correct Ort. Although encouraging as several correspondents have noted, in looking back at MEO's presentation material about the Heron reservoirs, the sandstone reservoirs are relatively tight - not unexpected at these depths and temperatures. I assume that Eni are running with a standard Logging While Drilling (LWD) log that comprises a GR (used for determining lithology) and a Resistivity log (used for determining formation fluid based on resistivity). They are probably not running with a Porosity log (generally a Sonic log) which is used to measure porosity. High formation resistivity is not by itself an indicator of gas saturation in reservoir. Sandstones that are tight (with little or no porosity - often due to silica or carbonate cement in the taking over the pore space) will also give high resistivity responses. So a porosity measurement is also required to more precisely estimate water, oil or gas saturation. High resistivities by themselves may mean nothing at all.

It would seem from presentation material put out by MEO that relatively low porosity reservoirs are expected at HS-1. Some porosity is required because that is what is needed to provide the "tank" for any hydrocarbons trapped. But what MEO seems to be looking at to make these reservoirs flow is natural fracture porosity and permeability. If there is sufficient porosity present together with fractures, then the well should flow gangbusters on test. I do note that there has been nothing put out whether fractures are present or not at HS-1

At this depth and temperature (thanks Dr Daz for this information) I don't expect oil to be present. But condensate and gas liquids could certainly be there. The CO2 content is difficult to determine from mud gas unless it is particularly high (it tends to dissolve in the mud and won't come out easily).

What is there and is it commercial? Well that has to wait until drilling is completed (it is very encouraging that it is still continuing presumably because gas shows are persisting and a GWC hasn't been encountered), the well logged and based on those evaluations, hopefully tested.


From Ort:
Indeed very positive data trickiling our way but shouldn't we maybe be leaving the champagne on ice till Meo present a more clear definitive result.....I recall that Dave Maughan had much to say about the porosity of the reservoirs at Heron ( I imagine this is what SS is hinting at re " being tight.." ) - at the last Agm

For laymen like myself here a quick dummies guide to porosity:


http://www.geomore.com/porosity-and-permeability-2/

As this has generally been viewed as an appraisal well ( which some have never quite understood ) the gas shows are indeed no surprise though the quantity may show considerable upside.....but shouldn't we be more concerned re flow tests , Co2 content, ......L like what I'm reading, and don't get me wrong, but for mine not done and dusted just yet. Anyway, hopefully the truth and nothing but the truth to be unveiled in the coming week or so that will be concrete and unequivocal . Regardless of results you've more than earned the bottle of RS I've got tucked away

Cheers Ort