On the primary and secondary petroleum generating characteristics of the Bowland Shale, northern England

Abstract

The Carboniferous Bowland Shale of northern England has drawn considerable attention because it has been estimated to have 1329 trillion cubic feet hydrocarbons in-place (gas and liquids) resource potential (Andrews 2013). Here we report on the oil and gas generation characteristics of three selected Bowland Shale whole-rock samples taken from cores and their respective kerogen concentrates. Compositional kinetics and phase properties of the primary and secondary fluids were calculated through the PhaseKinetics and GOR-Fit approaches and PVT modelling software. The three Bowland Shale samples contain immature, marine type II kerogen. Pyrolysate compositions imply primary generation of paraffinic–naphthenic–aromatic (PNA) oil with low contents of wax and sulphur. Bulk kinetic parameters have many similarities to those of productive American Palaeozoic marine shale plays. The secondary gas generation potential of Bowland Shale is greater than the primary gas potential although it requires a 10 kcal mol −1 higher activation energy to achieve peak production. Primary oil, primary gas and secondary gas reach their maximum generation at 137, 150 and 200°C respectively for a 3°C Ma −1 heating rate. Different driving forces of expulsion including the generation of hydrocarbon and overpressure caused by phase separation during sequential periods of subsidence and uplift could be inferred.

Can One-Run-Fixed-Arrhenius Kerogen Analysis Provide Comparable Organofacies Results to Detailed Palynological Analysis? A Case Study from a Prospective Mississippian Source Rock Reservoir (Bowland Shale, UK)

“…1 and 2); contain high organic matter richness (TOC o ; 3.78 to 11.16 wt%; average 5.83 wt%); have high pyrolysate yield (7.63 to 32.60; average 15.66); have low production indices (0.07 to 0.12; average 0.09); have moderate hydrogen indices (HI o ; 253 to 505; average 389); and contain predominantly Type II/III kerogen (constrained by transmitted white light observations; a significant portion of Type I kerogen is also assigned when data based on autofluorescence properties of the kerogen fraction is included; Tables 1, 2 and 3). These results demonstrate that organofacies A and intermediate, when sufficiently thermally mature, do have the potential to be a good source rock reservoir but the kerogen type (containing significant proportion of AOM/Type I and Type II) suggests that primary generation may result in higher oil yields rather than gas, but secondary gas generational potential is likely to be significant similar to that described by Yang et al (2015). However, the studied interval is not thermally mature and as such, it cannot be considered prospective but holds key information to predict prospective intervals within contemporaneous successions within the Bowland Basin, which have reached the thermal maturity required.…”

Deformation Experiments on Bowland and Posidonia Shale—Part I: Strength and Young’s Modulus at Ambient and In Situ pc–T Conditions

“…Alum shale (ALS) is highly overmature and was recovered from fresh cores of the Skelbro-2 well (Ghanizadeh et al 2014). Mature to overmature Bowland (BOS) shales are divided into Upper (BOS1-7, BOS11-14, BOS_OC) and Lower Bowland shales (BOS8-10) (Yang et al 2015). Samples BOS1-10 (z ≈ 2076-2719 m) were recovered from drill cores from the Preese Hall 1 well (PH1) drilled in 2010 (Green et al 2012) and samples BOS11-14 (z ≈ 32-80 m) were derived from the MHD13 well drilled in Marl Hill Moor (MHM).…”

Shale gas reserve evaluation by laboratory pyrolysis and gas holding capacity consistent with field data

“…Although hydrocarbon gases are not measured, an empirical relationship based on the S1 and S2 parameters (free and potential for generated hydrocarbons, respectively) to estimate shale gas yields has been developed 6 . Closed system pyrolysis uses micro-scale sealed-vessels (MSSV) where all volatiles are retained within the system 14,15 . The drawback with both techniques is that they do not replicate oil expulsion during maturation.…”