Competent Persons or Spin Doctors14 Jan 2019 10:28
gypsum. Gulf Keystone’s presentation at last year’s Finding Petroleum event in January was sandwiched between that of Hurricane and Cambridge Carbonates. Of particular interest, to GKP, were these two presentations made by the Hurricane Energy CEO, Dr Robert Trice, and Jo Garland’s colleague from Cambridge Carbonates. Indeed, Dr Trice has also included reference to the presentation on the Hurricane Energy website and has helpfully included a direct link to his presentation and the CC presentation can be found on FP. Sadly, however, Gulf Keystone Petroleum only seem to be in the habit of preventing access to such material.
How can Shaikan have such a huge Radius of Investigation (Transient Drainage Radius), world-class Productivity Indexes and high Permeability with a Fracture Porosity of just 0.4%, as has been claimed by ERCE in both CPRs. My belief is that there is some form of Secondary Fracture Porosity present in Shaikan that is not represented in the CPRs. Dr Trice said that the Lancaster Field’s 4% fracture porosity was seen, by comparison with global analogues, as ‘the average’ and, in his answer to Jo Garland, of Cambridge Carbonates, confirmed that the dissolution slots followed the micro fractures and that this formed a key and important contributing element to the total Fracture Porosity. Of course, dissolution slots following the fractures within the Shaikan Sargelu were evidenced by Mr Stafford in the AAPG Fracture Presentation April 2014. Furthermore, reviewing the Cambridge Carbonates presentation it seems quite clear that Shaikan does, indeed, show the hallmarks of karst dissolution. Cambridge Carbonates described the key evidence of karst as being ‘mud losses and bit drops’ both of which are evidenced in the now removed presentation material from GKP’s website. John Gerstenlauer even made an explicit public presentational reference to a Shaikan drill bit drop of three metres and huge mud losses. A carbonate reservoir specialist in the United States has said that such drill bit drops do not occur from fractures.
Karst, cavernous or large vugular dissolution would have a massive effect upon the Fracture Porosity of Shaikan. I would suggest, therefore, that the 0.4% Fracture Porosity figure, ‘adopted’ by ERCE is perhaps only for the Primary (tectonic) Fractures, which has an industry average 0.5% as stated by Cambridge Carbonates. That is why ERCE are comfortable in saying it’s the highest they’ve ever seen! Total Fracture Porosity, however, is the sum of (a) Primary Fracture Porosity, (b) Secondary Fracture Porosity resulting from dissolution, (c) Secondary Fracture Porosity resulting from vugs and (d) Secondary Fracture Porosity resulting from cavernous porosity or karst. The total Fracture Porosity depends upon the presence, and contribution of, those Secondary components.