The sectional view of three different damaged regions (marked P, Q and R) near the vicinity of a perforation is shown in the figure above. Choose the correct option matching the entries in GROUP X with the corresponding terms in GROUP Y.
GROUP X P Q R
GROUP Y (I) Grain fracturing (II) Charge and core debris (III) Compacted pulverized zone
Show Hint
Move outward from the tunnel tip: debris packed at the very tip, cracked individual grains right against the tunnel wall, and a wider crushed/compacted halo farther into the rock.
Step 1: Recall the physics of perforation damage in order of severity: When a shaped charge jet perforates casing, cement and formation rock, it leaves behind a graded pattern of rock damage rather than a single uniform effect. Right where the jet's energy is spent, solid debris from the charge and the excavated core material accumulates and can plug the channel. Around the channel, the intense but very brief shock wave fractures individual mineral grains. Farther out, where the shock has decayed somewhat but still exceeds the rock's strength, the pore network itself gets crushed and packed with fine particles, lowering permeability over a broader zone. Step 2: Map this order onto the arrow positions P, Q, R in the figure: Following the arrows in the figure from the innermost feature outward, P points at the very tip of the tunnel where solid material is trapped, so P corresponds to the charge and core debris, item (II). Q points to the band immediately touching the tunnel wall where the rock shows cracked grains, so Q corresponds to grain fracturing, item (I). R points to the outer, larger shaded region that extends farther into the formation, so R corresponds to the compacted pulverized zone, item (III). Step 3: Eliminate the other options using this mapping: Option (A) wrongly places grain fracturing at P instead of debris. Option (B) wrongly places compacted pulverized zone at Q. Option (C) wrongly swaps Q and R. Only option (D), P-II, Q-I, R-III, agrees with the physically graded damage pattern. Step 4: State the confirmed match: The matching P-II, Q-I, R-III is therefore the correct one. Final Answer: \[ \boxed{P-II;\ Q-I;\ R-III\ \text{(Option D)}} \]
