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Structures hidden at depth can be assessed through drill cores recovered from them. A crucial part of petroleum geology study is to interpret structures from these cores collected from vertical and inclined drilling operations reaching different depths. We deduce analytically ideal structures in unrolled/unwrapped images of cylindrical drill cores. These structures are: (i) orthogonal and conjugate fractures, (ii) single generation periodic folds and type-1 and type-2 superposed folds, (iii) listric faults and (iv) different types of angular unconformities. The sinuous curves as found in unrolled images are not always characteristic of the structures. Therefore accurate identification of structures would require additional information, such as the drill core itself. • Unrolled images of ideal structures in unwrapped/unrolled images of drill cores are presented. • Correct identification of structures, however, would require other sources of geological information. • The work has direct bearing in petroleum geoscience. [ABSTRACT FROM AUTHOR]

Studying the kinematics of listric faults is of great importance in petroleum geology and seismicity. The deformation related to listric faults differ from the planar fault plane case. This study involves 3-D co-ordinate geometry with spherical co-ordinates to deduce the effective-slip (e s) and the net-slip (n s) of listric faults of three ideal geometries: spherical, paraboloid and ellipsoidal. We perform 3D slip analyses on two types of listric faults (Type-1 and 2). Previous authors have considered these shapes of fault planes in their modeling. Using these e s , one can track material points before and after faulting, similar to Mukherjee (2019) applied on translational faults with planar fault planes. The n s can be divided into a strike-slip ( s n s ) and a dip-slip component ( d n s ). This resolution being done on the listric fault plane itself, n s ≠ ( s n s 2 + d n s 2 ) 0.5 . This is unlike the planar fault plane case. The purpose of 3D-geometric analysis of listric faults could be, in long run, the restoration of rock blocks that underwent listric faulting. • Kinematics of listric faults with ideal geometries are analyzes using 3-D co-ordinate geometry. • "Effective slip" is defined and its expressions for listric faults are deduced. • This work will be important in fault block restoration and modeling. [ABSTRACT FROM AUTHOR]