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An integrated approach was taken to utilize geochemistry information extracted from cuttings and produced oil samples to monitor vertical drainage between stacked reservoirs as well as to optimize well density in multi-bench cube development in the Montney play.Oil extracts from cuttings were profiled using high-resolution multi-dimensional gas chromatography (GCXGC) identifying 2,000+ compounds. Key reservoir properties such as indicators of oil saturation and matrix permeability were calculated using oil signatures extracted from cuttings. Subsequently produced oil were profiled using the same GCXGC method. Drainage frac height (DFH) and quantitative vertical production allocation by zone was conducted by building a geochemistry-based model and correlating the produced oils back to their contributing intervals represented by the cuttings.In this Montney case study, two neighboring pads with different cube designs were investigated. Pad 1 is a 12-well pad with 4 target benches and a stacked wellbore placement pattern, whereas Pad 2 is a 6-well pad with 3 target benches and a staggered wellbore placement pattern. Cuttings and produced oil samples were collected from both pads at every development bench, and geochemical DFHs and production allocations were estimated. The geochemical index from cuttings were in-line with the porosity log and wetness balance log collected while drilling. Based on the geochemical production allocation, both Pad 1 and Pad 2 showed vertical fracture growth was not constrained within the target bench. As a result, more vertical overlaps were detected which leads to a more severe vertical communication problem observed on Pad 1 where wellbores were vertically stacked above or below each other.In this study, the geochemical fingerprinting result was used to calibrate microseismic events. The quantitative production allocation allowed us to filter out any non-effective events and realistically capture the productive stimulated rock volume for optimizing well spacing and landing depth. Last but not least, the geochemical production allocation was successfully integrated with other reservoir surveillance data such as interference well testing.

This study integrates microseismic hydraulic fracture mapping with geochemical production profiling to understand the interaction between mechanical stratigraphy, fracture geometry, and effective drainage for wells landed in different benches of the STACK play in Oklahoma. Microseismic monitoring was used to map the extents of the hydraulic fracture system contacted during stimulation, while high resolution geochemical analysis or ‘fingerprinting’ was used to assess how different formations in the reservoir were draining. Microseismicity showed that hydraulic fracture growth from an Upper Meramec well rapidly cover the entire Meramec interval with some growth downward into the Woodford. Conversely, microseismicity initiating from a Woodford well clustered in that layer and grew upward into the Lower Meramec with time. Geochemical profiling closely matched the microseismic depth distributions for the associated well landing zones. Similar to the microseismic hydraulic heights from both Upper and Lower Meramec wells consistently produced from the entire Meramec, with additional recovery from the Woodford. Woodford landed wells produced Woodford oil with some production also coming from the Lower Meramec, also consistent with the microseismic depths. These production profiling trends were found to be very consistent across multiple sets of wells drilled into the same target formations. Integrating mapping of hydraulic fracture growth with geochemical assessment of the effective drainage within the hydraulically contacted zones provides unique insights into the reservoir contact and drainage. Understanding the mechanical stratigraphic controls on hydraulic fracture height growth relative to the reservoir drainage is key to informed decisions on wine-rack configurations for optimal reservoir drainage.

In this study, we present a method to monitor inter-well communication and drainage frac height through time based on unique geochemical fingerprint data collected from oils. This method does not require expensive instruments or interfere with production and its results were integrated with independent pressure gauge and well performance data to enable data-driven decisions on well spacing, well stacking and completion designs with different subsurface configurations. Produced oils of 9 horizontal wells over ~20 months and cuttings samples from the vertical section of an adjacent well were collected in the study area located in Midland Basin, Texas. The 9 producing wells were in two DSUs with two different well configurations, one drilled with two landing targets while the other with three. Thousands of chemical compounds that are naturally occurring in the produced oils and oils extracted from the cuttings, were profiled and interpreted geochemically. Drainage frac heights and quantitative production allocation by zone were conducted by building a geochemistry-based model correlating the produced oils back to their contributing intervals represented by the cuttings samples and their vertical depths. The probability of inter-well fluid communication between each of the well pairs was calculated based on the similarity of the geochemical fingerprints in the produced oils of the corresponding wells. Our data showed that the three targets scenario generated significantly more overlapped drainage vertically and vertical well communication than the two targets scenario. Up to ~60% of the drainage frac height of the Middle well in the three targets scenario overlapped with the Upper wells and ~20% overlapped with the Lower wells, while in the two targets scenario the Upper and Lower wells only showed ~40% overlapped vertical drainage. The lateral geochemical similarity index (SIL) calculation showed correlation between higher SIL (stronger lateral well communication) and poorer oil production rates, indicating well communication could impair well performance. The data also showed significant variation of lateral communication through time which was strongest about a month into production and then reduced through time. Even with the same spacing and completion design, the Upper wells showed higher SIL (i.e., more communication) than the Lower wells, indicating geology and completion design parameters such as sand and fluid volume, and clusters should be taken into consideration for future planning. Independent pressure data also supported these observations, providing critical evidence for optimizing the stacking, spacing, and completion designs of future development wells. Geochemical data in the produced oils carry significant information to reveal subsurface fluid flow and well interaction through time. It provides actionable data to support various field development decisions such as well spacing, well stacking, landing target optimization, well sequencing, and completion designs.