Page 384 - Fundamentals of Gas Shale Reservoirs

364 GAS SHALE CHALLENGES OVER THE ASSET LIFE CYCLE

Fracture
Porosity
Natural
Correlation Resistivity grain density porosity Gas in Rockview Frac zones migration Anisotropy Anisotropy fracture
NMR
map
GR–KTH 0.2 M2R1 2000 place mineral weights Barrier Delta pressure count
Caliper (OHMM) 0 2500
6 16 M2R2 (pu) Perf
(in) 0.2 (OHMM) 2000 (psi) [F2]
GR
0 200 M2R3 2000 (pu) [F2]
(gapi) 0.2 (OHMM) 2 Grain density 3
0 KTH 200 M2R6 (g/cc)
(gapi) 0.2 2000
(OHMM)
M2R9
0.2 2000
(OHMM)
0.2 M2RX 2000
(OHMM)

Track Nos.1 2 3 4 5 6 7 8 9 10 11 12 13 14

Mineralogy

Illite Smectite Kaolinite Chlorite Glauconite Apatite
Zeolites Anhydrite Salt Hematite Pyrite Organic C
Siderite Dolomite Calcite K–feldspar Plogioclase Quartz

FIGURE 17.2 Integrated shale analysis plot with mineralogy/lithology legend (Source: Baker Hughes).

favorable facies as the best intervals to initiate a fracture. along the horizontal lateral, and this topic is discussed later
Likewise, the most unfavorable sections of the most unfa- in this chapter. It is recommended that the logs and cores
vorable facies are also identified. The method classifies also be run and obtained from vertical appraisal wells and
zones for unfavorable frac intervals and for favorable frac that the characterization of the reservoir continue through
intervals. A similar criterion is applied for identifying the the appraisal phase.
optimum location to place the horizontal lateral. Conventional whole cores or sidewall cores and analysis
These types of logging surveys and cores are normally are required for calibrating logs and obtaining true mea-
only run or taken in vertical wells. From the numerous sured properties. Recommended analyses should include
mineral spectroscopy logs that have been run in shale porosity, permeability, saturations, gas analysis to include
wells, it is known that geochemistry (primarily TOC), adsorption/desorption isotherms and isotopes, triaxial com-
lithology, and mineralogy can vary foot by foot both verti- pression testing for static elastic properties, and thin section
cally and laterally in shale reservoirs. This author recom- studies. A wide variety of technologies are used to examine
mends that reservoir characteristics should be determined the lithology and mineral composition of shale. “Sample”