ASSUMED HYDROCARBON TYPE - Sweet, high gravity, volatile Oil

ROCK CHARACTERISTIC           DRILLING MUD SHOW

I  POROSITY
   A. TYPE
      1. INTERGRANULAR        MODERATE   
         INTERCRYSTAL-
         LINE, OR
         INTERFRAGMENTA;
      2. VUGGY                MODERATE-LARGE  
      3. FRACTURED            LARGE
B. QUALITY
      1. HIGH                 LARGE
      2. LOW                  SMALL
II PERMEABILITY
   A. HIGH
      1. MATRIX               LARGE
      2. FRACTURE             LARGE
   B. LOW-DENSITY             VERY SMALL
III DRILLABILITY
   A. HIGH                    LARGE
   B. LOW                     SMALL
IV COMPOSITION
   A. CARBONACEOUS  SH        
      PETROLIFEROUS SH        LARGE
   B. COAL                    LARGE
   C. SALT                    NIL
   D. ANHYDRITE               NIL (USUALLY)

MUD    HYDROCARBON          MUD SHOW
       & ROCK TYPES

HI
       HI PERM. - GAS       LO    LIB. & NO PROD. GAS
D      HI PERM. - OIL       MOD.  LIB. & NO PROD. GAS
E      LO PERM. - GAS       NORM. LIB. & NO PROD. GAS
N      LO PERM. - OIL       NORM. LIB. & NO PROD. GAS
S
I      HI PERM. - GAS       NORMAL LIB.& PROB. PROD. GAS
T      HI PERM. - OIL       NORMAL LIB.& POSS. PROD. GAS
Y      LO PERM. - GAS       NORMAL LIB.& POSS. PROD. GAS
       LO PERM. - OIL       NORMAL LIB.& DBTFUL PROD. GAS
LO

HI

W      HI PERM. - GAS       V/LO    LIB.  N. EFFECT
A      HI PERM. - OIL       LO      LIB.  N. EFFECT
T      LO PERM. - GAS       MOD.LO  LIB.  N. EFFECT
E      LO PERM. - OIL       NORMAL  LIB.  N. EFFECT
R
       (assume small overbalance)
L
O      HI PERM. - GAS         NORMAL EFFECT
S      HI PERM. - OIL         NORMAL EFFECT
S      LO PERM. - GAS         NORMAL EFFECT
       LO PERM. - OIL         NORMAL EFFECT
LO

HI

V                             LOWER TRAP EFFICIENCY
I                             INCREASES RECYCLED GAS
S
C
O
S
I
T                             ENHANCES TRAP EFFICIENCY
Y                             MINIMIZES RECYCLED GAS

LO

                                                                   TABLE NUMBER 3

TABLE 10-8. Classification of limestones according to depositional texture
********************************************************************************************
                                                   *                   *Depositional texture
              Depositional texture recognizable    *                   *not recognizable
********************************************************************************************
                                                   *Original components* 
                                                   *bound together dur-*
Original components not bound during deposition    *ing deposition     *
****************************************************                   *
Contains mud(fine silt and            *Lacks       *                   *
             clay size particles)     *mud         *                   *
****************************************************                   *
       Mud-supported       *     Grain-supported   *                   * Crystalline carbonate
****************************************************                   * (subdivide according
Less than    *   More than *          *            *                   * to physical or dia-
10 percent   *   10 percent*          *            *                   * genetic texture)
grains       *   grains    *          *            *                   *
****************************          *            *                   *
Mudstone     *   Wackestone*Packstone * Grainstone * Boundstone        *  
*********************************************************************************************
Source: After Dunham (1962), Table 1. by permission Amer. Assoc. Petrol. Geol.