High Resolution Mud Gas Isotopic Logging (HRMGIL) is a technique developed by IPEX and its partner Isotech Laboratories that utilizes gas samples taken from gas flow lines (after dryer) to quantify the yield of various gases and measure carbon isotopes on methane, ethane, propane and butane (C1-C4), whenever possible (Isotech 2000).
These are basically atmospheric samples of gas that are taken at broad intervals (ranging from 30 to 40m) throughout drilling, but at much narrower intervals in the reservoir zone, show (10-20m), or seal intervals (9-9m). The goal of HRMGIL is to aid assessment of gas and oil reservoirs particularly those drilled with oil based muds (OBM). This technique utilizes well known geochemical techniques applied toward formation evaluation, bypassed pay zones, and reservoir compartmentalization issues. Samples are collected using impermeable bottles (IsojarsŪ) or special stainless steel tubes (IsotubesŪ) under ambient pressure conditions.
Thus, these data may be used to determine and assess:
- Whether gas is thermogenic (economic) or biogenic (usu. non-economic)
- Possibility of down-dip pay
- Whether shows are "true" or "false" (e.g., gas kicks due to overpressure)
- Reservoir compartments
- Efficacy of seals
- Extent of thermogenic gas mixing
- Extent of biogenic-thermogenic gas mixing
- Gas thermal evolution