C6 subsurface envirt exercise

Exercise chapter 6 SUBSURFACE ENVIRONMENT 1/ List the four types of subsurface waters, and give a one sentence definition for each 2/ a ) How does salinity vary with depth? b ) What causes reversals o[.]

Exercise chapter 6: SUBSURFACE ENVIRONMENT 1/ List the four types of subsurface waters, and give a one sentence definition for each 2/ a.) How does salinity vary with depth? b.) What causes reversals of this vertical salinity trend? 3/ Below is a listing of rock types or groups, label each according to their thermal conductivity characteristics Use the terms "high" , "variable" , or "low" Sandstone Coal Limestone Rock salt Anhydrite Dolomite Shale - normal pressured Shale - overpressured What are the three main causes of regional variations in geothermal gradients? 5/ Why high geothermal gradients favor oil production? 6/ There are two basic types of subsurface pressures which together constitute the total overburden pressure What are they? 7/ Below is a listing of causes of subnormal (under) or supernormal (over) pressures Label each with either the "underpressure" or overpressure" which they would cause _ is caused by an artesian water system _ is caused by diagenesis, where water is expelled _ is caused by thermal expansion of water _ is caused by an increase in pore volume by decompression or fracturing _ is caused by under compaction of shale _ is caused by an increase in pore volume due to dissolution of mineral cements _ is caused by a lowering of reservoir temperature 8*/ Sketch the potentiometric surface on the cross section ( Figure 1) Figure 9*/ On this pressure/temperature graph for a crude oil/gas system, indicate the areas occupied by liquid, vapor, and liquid & vapor phase(s) Label the critical point, the bubble-point curve and the dew-point curve (Figure 2) Figure 10*/ Below is a listing of basin characteristics, each belonging to either a "juvenile", "intermediate", or "senile" basin Mark each with a J for juvenile, I for intermediate, S for senile _ dynamic fluid system, strong marine influences _ widespread meteoric water in subsurface _ meteoric water invasion at margins of basins _ fluid pressures mostly hydrostatic, some artesian water systems _ generally only hydrostatic pressure gradients _ fluid movement compaction-induced, moving outwards towards margins _ invasion of meteoric water unimportant _ compaction of shales nearly complete _ overpressured shales common _ still actively receiving sediments _ mostly removed from marine influences _ oil beginning to be degraded at basin margins _ extensive degradation of oil 11/ There are 04 chemical composition relationships of ground water (classificated by Sulin-Russia) Determine the type and origin of them, What type would have most indication that relate to petroleum accumulation? >1; < and 1; > and 1; 1 and