Lab-9 Interpretation of Gas Shows The following parameters are used to the analysis of gas logs, wetness (Wh), Balance (Bh), Character (Ch), BAR2 (C₁B/C₂). The Wetness, Balance, and Character ratios come from the interpretation of hydrocarbon shows using light (C₁-Cs) hydrocarbon gases from mud log data. Wetness (Wh): geochemical parameter serving to the quantitative representation of the component ratios in proportion to C₁. The ratios are calculated as follows: Wh- C2 + C3+ IC4+ NC4+ICS+ NCS C1 + C2+ C3 + IC4 + NC4+ ICS+ NCS . 100 Balance (Bh): geochemical parameter which expresses the relation of the light components to the heavy ones. If the Bh value is high the HC (gas) is dominant, if it is low the heavy components (oil) to be plotted along with Wh. The approximation between them and the cross-over mean transition from the light HC (gas, gas precipitation) toward the heavy one (oil). C1 + CZ Bh= C3+1C4+NC4 +ICS + NCS Character (Ch): If 0.5 <Wh and a Bh<Wh and Ch>0.5 wet or condensate If 0.5 <Wh <17.5 and Bh, Wh and Ch>0.5 oil reservoir of high API density and / or high GOR Ch- IC4+ NC4+ICS + NCS C3 BAR2 (Baroid, C₁/C₂): empirical parameter and it can be used to the interpretation of HC origin. Beside the Wh, Bh interpretation, it can be used to indicate productive zone or wet zone as well. - If BAR2 <2, non-production zone, if Wh indicates that as well, then oil residue - If2<BAR2 <10, gas coming from oil reservoir - 10 <BAR2< 35, gas coming from gas reservoir - If 35< BAR2 gas in contact with water nonproductive The Wetness, Balance, ratios Interpretation Wetness Ratio Balance Ratio Reservoir Fluid / Production Potential > 100 Very Light, Dry Gas. Typically non-associated and non- productive such as the occurrence of high pressured methane, metagenic cracking below the oil window, bacterial methane, etc <100 <0.5 Possible production of light, dry gas Wetness < Balance < 100 0.5-17.5 Productive gas, increasing in wetness as the curves are closer together <Wetness 0.5-17.5 Productive, very wet gas or condensate or high gravity oil with high GOR (Balance < Wetness indicates liquid, but Wetness still indicates gas) <Wetness 17.5-40 Productive oil with decreasing gravity as the curve separation increases << Wetness 17.5-40 Lower production potential of low gravity, low gas saturation oil > 40 Very low gravity or residual oil
Ex-1: The light hydrocarbon gases (C₁-Cs) from mud log data's reading 50% C₁. 20% C₂, 10% C₁, 15% IC+, 4% NC+, 0.5% ICs, and 0.5% NCs. Calculate, Wetness (Wh), Balance (Bh), Character (Ch) and BAR2. then interpret the production potential for these data's Ex-2: The figure below represents the light hydrocarbon gases (C₁-C₁) from gas log 1- Descript the reservoir fluid in the interval (4360-4400 m) depending on the (Wh) & (Bh) 2- Descript the reservoir fluid in the interval (4310-4360 m) depending on the (BAR2) 3- Calculate wetness, balance & character in the depth (4250 m) then describe ROP GAS RATIO 1:30 1009 (M./M) CO2 (ppm) 100 10 10000 Depth (m) LITHOLOGY B 4040 1 1 1 **** 303 I PE WETHESS
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