Page 240 - Origin and Prediction of Abnormal Formation Pressures

212 V.I. ZILBERMAN, V.A. SEREBRYAKOV, M.V. GORFUNKEL, G.V. CHILINGAR AND J.O. ROBERTSON JR.

,_ lz a)>" Resistivity Log Drilling Rate
O s:~ O M2AO.25B Mud Log
"'--0 ~ r'O Ohm-m i min/m 0 2 4%
-1-- c~ "~ 5 10 15 20 40 60 80 0 20 40%
_ L LI'L hLl" ~ I I I ~ I ' i
L. t. L L
I. L L,
L, L, e. ~,
155o
L L, ~. i.
L L L,
L I, ~,
svt ~'-'4~"~-
Pl

_--__--_._=-J~

'
1600__I~_ 3
~
~
~

LIIlllIIlIII
~-zz ~-~ c..- ~ - - -
1650 :~o

:! 2--

Lithological barrier ~ Gypsum [-~ Kartamysh Formation
~-~ Gas clay ~ Siltstone [-~ Svyatogor Formation
Rock salt ~ Shale I~] Commercial gas-saturated
portion of Svyatogor Formation
Anhydrite ~ Dolomite
Limestone ~ Sandstone
Fig. 9-2. Position of the lithologic barrier and the 'gas clay' in the type section of the Svyatogor Formation,
Shebelinka Field. (Modified after Zilberman et al., 1971.)

accumulation with AHFP. The drilling rate increases upon entering the 'gas clay', which
ranges from 3 to 10 m in thickness. The gas-clay and lithologic barrier are present in
the other fields adjacent to the Shebelinka Field (Efremov, Melikhov, Medvedov and