ADCO has drilled a number of wells and evaluated hydrocarbon potential of the Middle Cretaceous Wasia Group Unconventional reservoirs onshore Abu Dhabi since 2012. Latest logging and core analysis technologies were applied to assess key parameters such as Total Organic Carbon (TOC), source rock maturity, mineral compositions and fluid saturations, as well as geomechanical parameters such as Young's modulus, Poisson's ratio and minimum horizontal stresses. To date more than 2500ft of core has been extracted, described and analysed. We understand that ADCO has, by far, the largest data base among all the OPCOS with regards to unconventional play and has gained a significant local learning curve ahieved over the last 3 years. In addition to triple combo data, log data acquired consists of NMR, high resolution lateralog, dielectric logs, and mineral spectroscopy, cross dipole sonic, borehole imaging and sonic scanner, routine and advanced mudlogging. Core analysis consists of crushed rock analysis, pyrolysis and rock mechanics testing. Significantly high mud gas readings, observation of oil staining, odor, and fluorescence under UV light indicate presence of oil over large sections of the acquired cores and side wall cores from various geographically spread wells. Recently, we have conducted 5000 TOC and 1500 Pyrolysis measurements from core and cuttings samples in 110 wells spread all over Abu Dhabi. This data clearly demonstrate that large sections of Wasia Group bear excellent source rock quality in several wells located in large segments of onshore Abu Dhabi. Visual inspection of core and TOC measurements indicate that high frequency jet black centimeter scale organically rich lamellae often exceeding 20% TOC in several wells are not uncommon. The unconventional reservoir rocks are composed of predominantly clean and tight matrix carbonate mudstones and wackestones. Preliminary results of the current exploration campaign within the ADCO concession are very encouraging, showing indications of hydrocarbon presence. Formation testing is planned in the near future to confirm the Unconventional play in Abu Dhabi. The paper focuses on an integrated multi-disciplinary approach covering petrophysical, geological, geochemical and geomechanical assessment with the ultimate goal to determine optimal parameters for formation testing and production.

Fluid identification is an important step in reservoir characterization and hydrocarbon volume estimation of an exploratory target. Volatile oil / Gas condensate reservoirs are well known for complex behavior due to near critical fluid nature. Objective of this study was to identify fluid nature in a low permeability reservoir where a single phase PVT fluid could not be obtained. This study describes a carefully designed analytical and interpretive workflow that utilized analyses of the separator samples and integration of the data from G&G sources to discern fluid nature. This paper describes the methodology of identifying fluid nature of collected separator samples from ADCO's exploratory reservoir in a field that has potential to add significant reserves to its portfolio. Due to high pressure encountered during drilling of the exploration target reservoir, Wireline Formation Tester (WFT) pressure gradient and bottom-hole samples were not acquired. Wireline logs were acquired after several weeks and consequently did not help in distinguishing the hydrocarbon type. Production test conducted across the 6 ft thick top layer resulted in 49° API oil with GOR varying from 3000 – 4000 scf/bbl. Three (03) sets of oil and gas separator samples were acquired and physical recombination was performed in the PVT laboratory at reservoir conditions using two different GOR values. Composition analysis of separator liquid was also performed and compared to the same reservoir in analogue fields at comparable depth. Physical recombination at GOR values of 3000 and 3759 scf/stb exhibited oil and gas-condensate behavior at respective GORs. Composition analysis of separator liquid also indicated significant amount of heavy components (C7+: 65.5% and C12+: 23.6%). Reservoir compositional data was plotted and compared to similar oil / gas-condensate reservoirs from nearby fields. Fluid was identified to be of volatile nature based on PVT study as bubble and dew points pressures were very close in recombined samples. The mud log data showed high total gas reading of 17% in the zone of interest. An assessment of hydrocarbon phase at this high total gas reading based on Wetness (Wh) and Balance (Bh) ratios already indicates presence of light oil. Further PVT work including an attempt to acquire WFT sampling of a single phase fluid is recommended in appraisal wells to thoroughly understand the near critical hydrocarbon phase in the reservoir of interest.

Kadanwari field in Middle Indus Basin (Pakistan) was discovered in 1989 and brought on stream in 1995. The producing reservoirs are Cretaceous Lower Goru sands D-E-F-G. The gas production started from better quality E and F sands; after 2004 layer G started to drain western block of the field, with the first hydraulic fracture job made in Pakistan (well A). Layer G represents a complex target for petrophysical characterization; reservoir sandstones are micro-porosity rich, with variable presence of Chlorite affecting flow properties. Positive results encouraged the operator to drill & frac well B and to consider possibility to extend gas production throughout western block, including sand reservoirs of variable quality, from moderate to tight. The paper describes how reservoir study faced layer G complexity and how production data of wells A and B allowed a post fracjob evaluation integrating well-test data and frac-job interpretations into 3D dynamic model. After history match, the computed GOIP suggested an infilling program in G sand reservoir, with side-tracks of existing wells and new wells, all hydraulically fractured. So far, one sidetrack and one new well have been drilled; results fully confirmed the complexity of local geological setting. The sidetrack revealed rock quality slightly better than expected (frac not necessary). Pilot well C targeted G-Sand in a sweet seismic anomaly in western area, a gas flare was observed during DST pre-frac. Mini-Fall Off was conducted to estimate closure pressure and effective mobility, but permeability computed from MFO was not conclusive due to important filtrate invasion. DST post hydraulic fracture job confirmed commercial gas rate production higher than 1 MMscfd with a peak of 3.5 MMscfd. The successful pilot well results open new horizon to improve reserve from tight sand of Lower Goru formation.