Due to maturity inversion from shallower west to the deeper east in Delaware basin, the shallower western slope of Delaware basin features higher GOR than the deeper eastern part of the sub-basin. This poses risk of higher GOR yet low oil production in the Northern part which already happened in the southern paleo-high block of the Delaware sub-basin. We report our extensive integrated/interdisciplinary analysis of the block around the Potash Lake area in Eddy co. (PLE).
In Permian basin two surprise reversals of maturity relative to depth of burial are revealed, i.e. basin wide shallow-deep reversal (ManosTA, 2018), and possible single spot vertical reversal as we will discuss here in details. These reversals coupled with faults linked migrations and ground water issues, cause complications for oil production in the Permian basin, Delaware Sub-basin in particular. The resulting huge variations of GOR and earlier appearance of bubble point during production will significantly affect final value of the assets. Mitigation and optimization of oil asset and production through oil high resolution GC, mud gas isotope logging, as well as source rock maturity identification through Raman and semi-empirical HI index are discussed. We discussed the gas isotope-maturity model specific to Permian marine kerogens, and also approximate GOR-maturity template, and use NOVO's GOR characterization in NorthWestern shelf of the Delware sub-basin as a case study.
When textbook teaches about maturity model, graphs of Permian basin like below are often used. Note the oil-wet gas windows are horizontal lines indicating maturity is proportional to depth of burial in a single sub-basin in the textbook model; and the Delaware and Midland sub-basins and central platform have different level of maturity but the trend is same, i.e. getting more mature with depth of burial at each single location.
And carbon isotope trends of methane, ethane & propane follow the maturity plot, i.e. 3 straight lines, as shown in Figure 2. If all follow such maturity trends, life in the Delaware or Permian basin will be boring indeed.