"this is a pretty important section. @afawcett, also alluded to one of the key points here. Here it is again...All the blue bits could be a connected, fractured rock, reservoir. Unlike primary porosity, fracture porosity is not exclusively related to rock type alone. And the thrust faults may not in themselves form seals along the entirety of the plane."
Significant in the sense that early on (2016) an article appeared claiming 8.2B barrels of oil had been discovered at Motembo hypothetically by MEO at the time.. However this claim soon met with some conjecture and a slight retraction was issued which stated the discovery was subject to future project developments, including interpretation of all the seismic data and geochemical (Microseep) samples. !
Does oil exist in Motembo? During July 2016 international media publicised a report published by the Australian firm MEO on the hypothetical discovery of high quality, light crude oil reserves of about 8200 million barrels in a zone known as Motembo, a 2380 km2 area located in the central province of Villa Clara, which is the first region in Cuba where oil was obtained. Logically, this notice generated great expectations both in Cuba and the rest of the world. However, some CUPET authorities declared in a press conference some weeks later that there had been erroneous misrepresentation of the note published by the Australian company, which did not use the terms “confirmed discovery” or “finding”, but only the “identification of potential, important amounts of oil which can be recovered under the application of future development projects”. According to announcements by MEO, confirmation and further validation that there are thousands of millions of barrels of oil at this site requires supplementary evaluation, exploration and analysis operations distributed in different phases: 2D seismic operations, profitability and prospective studies, deep drilling and oil quality testing. MEO signed a shared production agreement with CUPET in September 2015, and is carrying out oil exploration studies at Block 9 in Motembo region (see Figure 4), including review and reprocessing of the existing 2D seismic data; geochemical samples acquisition and evaluation; and completing new 2D seismic operations in an additional 200 km zone.
As to the real figures, it seemed they ranged from 1.1 to 44 billion barrels potential reserves of oip, with a best case scenario of 12.7B.
McDaniels seemed to then scale back the wild assessment ranges when in 2018 they completed a review of the data presented and came to agreement on an increase from 12.7 to 15.7B barrels over block 9 which can be assumed to still be the best case scenario.
That earlier estimate, or at least a portion of it, was later increased again on discovery at Alameda whereby 6.4b barrels oip were assessed by McDaniels of which 362 MMBO was deemed recoverable using the historical Cuban heavy oil field recovery factor of 5%. Of which the actual value likely to be achieved is up for debate. Ref below.
Now if we take the pic of the seizmic at Alameda as released in the last resource update and compare that to the one released on Zapato last week we might well assume they know a lot more downhole now than they did previously. And whilst it aint to scale I don't imagine, the potential does appear huge on first glance that Zapato eclipses Alameda and maybe that 8.2B barrels isn't beyond scope, all things considered?
You would have also have to think that the seizmic above, taken from verified logs, is similar to that below from the last ann and therefore it's possible, if not reasonable, to think they were at least deep enough into or through any seizmic reflector for it not to have a bearing on the newly depicted schematic?
"Based on interpretation of the available information, the well is now possibly immediately above the seismic reflector which represents the base of the ophiolite sequence".
Hence "We continue to persist with the drilling of Zapato-1 as we believe there must be a productive hydrocarbon zone underneath the volcanics we’re drilling through" & "We chose the Zapato structure for our second exploration well not just for its potential in its own right but because establishing the validity of this thesis unlocks the potential for similar and multiple very large plays in adjacent structures in Block 9, such as the A2 lead. As previously flagged, the massive adjacent Varadero field that has been in production since the late 70s was drilled on a similar gravity anomaly and that those rocks are the same as what has been thrust deeper at Zapato"
Allude to just how significant it may be.. Time will tell so GLTAH and here's hoping they get to flow Zapato cause that will really light things up IMO.
Ref. Field planning & recovery etc below & if I may ask;
The other consideration is of course the recovery factor and on this we have some guidance perhaps? N section at 2950-3000m deep and for the most part all of Alameda was a continuation of a fractured carbonate lithology which is handy because there have been at least 310 of those studied globally so we can draw some parallels at least. The first point of note is that 230 BBOE in recoverable reserves have been drawn from the 310 reservoirs at an average of 740 MBOE each so we aint talking anything less than globally significant here.
And whilst recovery factors vary it is important to note that none were below 7% (which is a 20% increase on current estimates) and of those lower figures, out of 54 wells examined, there were only 2 in single digits (7 & 8%) 1 at 10% and another 2 at 15% and another at 17%.. The rest were closer to the global average at around 20% using modern recovery techniques, including horizontal drilling.
Sherritt.. The main non-Cuban operator in Cuba is Sherritt International, a Toronto mining company which has been active in Cuba for more than 20 years. This firm operates Puerto Escondido, Yumuri, and Varadero West oil fields under two production-sharing contracts (PSC). In May 2014 the company negotiated a 10-year extension to the Puerto Escondido-Yumuri PSC. It has drilled eight wells, one more than required by the extension terms, and has ended the extension drilling programme. Six of the wells produce oil, one is suspended, and one has been abandoned.
"Since 1992, the Corporation’s Cuban Oil operations have produced over 226 million barrels of heavy oil on a gross workinginterest basis. The Corporation has a strong track record in directional drilling in the fold and thrust belt located along the northcoast of Cuba. All of the Corporation’s producing wells are directionally drilled from onshore locations along the north coast ofCuba between Havana and C´ardenas. These directional wells target oil reservoirs situated offshore below the adjacent seabed.These oil bearing reservoirs typically produce at depths ranging from 1,200 metres to 2,000 metres below sea level. Using currentequipment and technology, the Corporation has drilled directional wells up to 5,660 metres in length, extending laterally up to4,700 metres from the surface location".
The 310 fractured reservoirs examined in this study havecombined recoverable reserves of 230 BBOE. For those fieldswhere ultimate recovery can be reliably determined, ultimaterecovery factors can be said to range 7–65% with a mean average of33% (Fig. 2). Initial well rates range from 100 to 8000 BOPD (meanaverage 3700 BOPD) and well EUR ranges from 0.32 to 15 MMBO(mean average 8 MMBO). As most fractured reservoirs haverelatively low primary recovery factors, Improved Oil Recovery(IOR) and Enhanced Oil Recovery (EOR) techniques are widelyemployed within this dataset as a means to improve recoveryefficiency, but the results are highly variable with both low- andhigh-side outcomes occurring (Fig. 3). This dataset therefore coversa broad spectrum of available data on fractured reservoirs and istaken to be representative of both the natural variability inherent tothese reservoirs, and of the variability of outcomes when IOR andEOR methods are applied
This study categorises fractured reservoirs in three groups: (1) Type 1: characterized by a tight matrix where fractures andsolution-enhanced fracture porosity provide both storage capacity and fluid-flow pathways; (2) Type 2: characterized by amacroporous matrix which provides the primary storage capacity where fractures and solution-enhanced fracture porosityprovide essential fluid-flow pathways; and (3) Type 3: characterized by a microporous matrix which provides all storagecapacity where fractures only provide essential fluid-flow pathways. Differentiation is made between controls imparted byinherent natural conditions, such as rock and fluid properties and natural drive mechanisms, and human controls, such as choiceof development scheme and reservoir management practices.
Now I'm going out on a limb here and happy to be corrected but I believe the two discoveries will fall into the Type 11 category, although possibly type 1? What do people think?
Which gives a Recovery Factor (RF) plot as per the distribution below.. Because the classification es muy importante Senor.. Si.!
Implications for development strategy The fractured reservoir classification scheme presented here haswide implications for field development strategy. While permeability enhancement by natural fractures is critical to defining a fracturedreservoir, it is matrix properties that define the various fracturedreservoir types. Using an objective and consistent definition of rockmatrix properties, such as porosity type and poroperm characteristics (Fig. 6), this study categorises fractured reservoirs as Type 1(tight matrix), Type 2 (macroporous matrix) and Type 3(microporous matrix). This classification scheme describes theunique behaviour of the 310 fractured reservoirs examined by thisstudy into discrete groups that perform similarly within theconstraints of the definition. This forms the basis for the ‘Types’and while it is possible to sub-divide these types further (forinstance, into Type 1 basement and Type 1 carbonate), thisclassification scheme attempts to make the subdivision of fracturedreservoirs at the highest possible level, in order to have the widestpractical application. Existing fractured reservoir classifications do not adequatelydifferentiate certain types of fractured reservoirs as the definitionand delineation for the different types of fractured reservoirs isqualitative in nature, relying on arbitrary porosity-permeability cutoffs and subjective judgement of commerciality. Consequently, it isdifficult to apply these classification schemes for the understandingof fundamental controls on reservoir performance and recoveryefficiency. The fractured reservoir classification scheme presentedin this study is based on reservoir and production characteristics,including rock matrix properties and fractures in the capacity of bothstorage and fluid conduit. As there is little overlap between thevarious types of fractured reservoirs (Fig. 6), it can be easilyimplemented to optimize development and production in naturallyfractured reservoirs, particularly during the early stage of a fielddevelopment when direct measurement information is limited.
Numerous fractured reservoir examples from around the worldindicate that Type 1, Type 2 and Type 3 fractured reservoirs definedin this study are comprised of fundamentally different rock typesand characterized by different natural drive mechanisms, and hencerender different development scheme choices. Within this newclassification scheme differentiation is made between controlsimparted by inherent natural conditions, such as rock and fluidproperties and natural drive mechanisms, v. human controls, such aschoice of development schemes and reservoir managementpractices. Differentiation of these controls allows reservoirperformance and recovery efficiency to be understood in context,and for fractured reservoirs to be classified in term of their intrinsicwhole-rock properties. Best practices and lessons learned from theglobal analogues for each of the fractured reservoir types can beused to validate development concepts, quantify resource assessments, and calibrate production performance.
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