Chapter 3 Reserve Estimation. Lecture notes for PET 370 Spring 2012 Prepared by: Thomas W. Engler, Ph.D., P.E.

Transcription

1 Chapter 3 Reserve Estmaton Lecture notes for PET 370 prng 2012 Prepared by: Thomas W. Engler, Ph.D., P.E.

2 Volumetrc N ol n 7758A B o place, n h f (1 1 ) here, N = ol n place, stb A = dranage area, acres B o = ntal formaton volume factor,rb/stb h = ndvdual zone thckness, ft f = porosty, fracton = ater saturaton, fracton Reserves are defned by: R = N * (E r ) E r = recovery factor

3 Depth merge & correlate onc Measured Water ample Densty Neutron others Lthology Gas/Lqud Publshed Water Tables R = R o /F P log P a F f m Vsh F * R Rt Inducton log GR Laterologs Porosty logs o = 1 Volumetrc ol n place, 7758A n N hf (1 ) Bo 1 Reserves, R = N * RF Flochart for Well Log Interpretaton

4 Defnton of Reservor Intervals

5 Cutoff Values 1. hale content (Vsh) elmnate the porton of the formaton hch contans large quanttes of shale. Vshcutoff 20 to 30 % (Note: shale plays up to 40 to 50%) GRO AND 2. Porosty elmnate the porton of the formaton hch s lo porosty (and lo permeablty) and therefore ould be nonproductve. andstones fcutoff 5% to 15% consoldated frable, unconsoldated Carbonates fcutoff 4% (Note: shale plays ~ 3 to 4%) NET AND 3. Water saturaton elmnate the porton of the formaton hch contans large volumes of ater n the pore space. andstones cutoff 60% Carbonates cutoff 50% NET PAY

6 Cutoff Values pecfc Correlaton Applcable to U.. gulf coast sands Correlaton beteen k, f, and Assumes ol/ater vscosty rato = 2.0

7 Averagng Porosty thckness eghted average f n f h 1 n h 1 h 1 h 2 h 3 f 1 f 2 f 3 Water saturaton volume eghted average n 1 n φ 1 φ h h

8 Reservor Volume V b V b h A 1 * 3 n A n A n A n1 or h A A 2 n n1

9 Recovery Factor Determned from: 1. dsplacement effcency studes 2. correlatons based on statstcal studes of partcular types of reservor mechansms OIL volumetrc reservors E r 1 g 1 1 Total free gas saturaton at abandonment by core analyss. Assumes core fluds (ol and ater) are dsplaced by expanson of the lberated gas hle removng the core to the surface smlar process to depleton. B o B o hydraulc reservors E r 1 1 or Estmate or from the remanng ol n the cores after flushed by mud fltrate and expanson of gas dsplacement process

10 Recovery Factor GA Volumetrc Reservors E r 1 B g B ga Hydraulc Reservors E r 1 B g gr 1 B ga

11 Recovery Factor From dsplacement of reservor fluds (nvason) usng ell logs

12 Recovery Factor From dsplacement of reservor fluds (nvason) usng ell logs Dfference beteen ntal ol saturaton, o and the resdual ol saturaton, or, that remans after the formaton s nvaded by ater: om = o or Inferrng mud fltrate nvason as an effcent dsplacement mechansm, then om = xo Recovery factor for ater drve reservors, E r d xo 1...for depleton drve, use rule of thumb of 1/2 of (RF) d

13 Recovery Factor tatstcal Performance oln Gor Ol gravty maxmum andstones average mnmum maxmum Carbonates average mnmum oluton Gas Drve Reservors (Arps, 1962) Drve andstones Carbonates mnmum average maxmum mnmum average maxmum Water drve oluton gas drve thout supplemental drves oluton gas drve th supplemental drves Gas cap drve Combned th sandstone Gravty dranage Data not avalable Gas depleton Gas ater drve Recovery factor for dfferent drve mechansms

14 Electrcal Propertes of Rocks References Chapter 11, ec , Bassoun, Z: Theory, Measurement, and Interpretaton of Well Logs, PE Textbook eres, Vol. 4, (1994) Corelab, Fundamentals of Core Analyss, Houston, TX (1983), Chapter 7