mshoemaker@scicatoil.com | 713-515-1155 | Houston
Maximizing Fracture Stimulation for Enhanced Energy Production
SciCat Geo (or SciCat®) is a subsidiary of SciCat Oil LLC founded in 2011, and is a subsurface technology advisory company
3D Mechanical Earth Models Integrated with 3D Seismic Geomechanics for In-situ Stress Variability, Delaware Basin
Anisotropic Stress Measured at the Well Pad and Far Field in 3D Space for Stimulated Rock Volume, Midland Basin
Stress Variability from In-situ Seismic Geomechanics vs Interpolated Min Stress from Vertical Wells, Midland Basin
Strategic Partners for Subsurface / Completions Engineering
Geothermal Energy & CO2 Storage Using Seismic Geomechanics
Geological parameters that must be taken into consideration before the implementation of CO2 storage methods include porosity-permeability and the thickness and depth of the reservoir formation which speaks to the in-situ stress state of the Earth, in addition to cap rock integrity and sealing properties of faults (Koukouzas et al., 2020).
Additional factors that substantially affect the implementation of geological storage methods involve environmental issues (CO2 leakage) which speaks to the mechanical stress state of the Earth.
Like the conventional petroleum system, a Carbon Storage System (CSS) has essential subsurface elements with uncertainty and risk assigned to each element that must be investigated and defined, in this case for safe and efficient containment prior to application which speaks to integrity of the rock and minimal horizontal stress.
Emerging methods involve not only the artificial creation of storage space and confinement in tight rocks, but safe containment which requires measurement of rock properties and in-situ stress states of the Earth involving geomechanical stratigraphy and the Mechanical Earth Model (or MEM).
Such methods represent a similar approach with application of in-situ stress states and the MEM relative to the development of unconventional oil and gas resources and fracture stimulation of tight rocks, in this case for environmentally safe containment of CO2 with knowledge of geomechanics and subsequent fracture geometry in defining the CSS.
Permian Basin Case Study: Frac Design Using SciCat® Stress
Far-field stress variability from SciCat® is driven by in-situ 3D seismic geomechanics defined by lithofacies and mechanical stratigraphy of the rocks which ultimately governs fracture geometry including height and length.
For example, stacked horizontal wellbores landed in the Lower Spraberry formation, seen here from the Permian Basin, are typically separated vertically by just 200 ft. with stress differentials greater than 1,200 psi (red to purple). The black curves define individual vertical stress profiles extracted from the same section which are vertically sampled at 1 ft.
The upper landing is characteristic of higher stress rocks due to the addition of clay and organics by volume warranting a tighter spacing of 200 ft. totaling 22 stages. The lower "landing2" zone is characteristic of lower stress (more brittle) due to proportionally less clay and more carbonates, thus warranting a relatively wider spacing of 250 ft. totaling just 17 stages.
With less frac stages, the lower landing completion costs are reduced by ~$350,000 per well, a significant savings for a 12-well pad and without compromising production. Optimal stage spacing from stress heterogeneity can be confirmed using fracture modeling as seen below.
3D Fracture Geometry Modeling
Seismic-stress cubes are corrected for anisotropy using core integrated with mechanical earth models, and can be input directly into fracture geometry simulators like GOHFER® with the necessary stress variability at the area of interest, contrary to current methods that interpolate geomechanics from vertical wells.
Stress is Input Directly into Fracture Geometry Simulators
E&P’s operating tight oil and gas plays continue to implement development strategies that involve cookie-cutter completion designs that use identical geometric stage / cluster spacing. Such development strategies fail to account for changes in geology, specifically minimum stress heterogeneity near wellbore and far-field which governs stimulated fracture complexity. The measured stress can be input directly into 3D fracture geometry simulators like GOHFER® .
The same Lower Spraberry example from the Permian shows stacked horizontal wellbores with stress heterogeneity measured in-situ by seismic geomechanics (bottom section), contrary to interpolated stress from vertical logs without seismic which fails to account for the vertical stress differential separating the stacked wellbores (middle section). Without accounting for stress heterogeneity, modeled fracture lengths appear equal and the stacked wellbores would have otherwise been completed identically at significantly increased cost.
Stress Heterogeneity for Optimal Completions Design
Near wellbore minimum horizontal stress from SciCat® can be input directly into completion modeling software in 1D and 3D space for optimal stage and cluster spacing determined by stress differentials for enhanced treatment sensitivity analysis that is data driven, resulting in optimized fracture stimulation with mitigation of stage-to-stage and interwell frac hits. Example here is from CORDAX ® using stress input from SciCat.
Seismic Geomechanics for Frac Hit Mitigation
Changes in geology define intrinsic 3D seismic geomechanics or elastic properties of tight rock that are effectively measured by the seismic directly at the area of interest. SciCat integrates the seismic with mechanical earth models defining near wellbore and far field vertical and horizontal stress variability for interwell frac hit mitigation in 1D and 3D space.
Minimum Horizontal Stress for Landing and Trajectory Design
Lateral and vertical drilling markers for structural in-zone trajectory design and drilling can now be defined based on mineralogy contrasts that define the geomechanics and stress measured by the inverted 3D seismic geomechanics, representing a first step in minimizing drill time for cost reduction.
Mechanical Earth Solutions for Acreage High Grading
Quantitative mapping of stress heterogeneity allows for acreage high-grading ahead of the drill bit to identify completion quality "sweet spot" fairways and areas more prone to frac hits and parent-child issues. Cookie-cutter development strategies assume subsurface isotropy and fail to account for rock heterogeneity.
Mechanical Earth Solutions for Pad Design and Well Spacing
Pre-drill parameterization of fracture geometry models for horizontal landing, well spacing, and engineered treatment design requires an anisotropic in-situ stress measurement defining the vertical and lateral heterogeneity of geomechanical properties defined by the seismic, along horizontal and vertical wellbores.
Why SciCat?
Unconventional exploration and production (E&P) companies are now focused on strong balance sheets and free cash flows more so than ever. This speaks to capital efficiency across the value chain, involving key improvements in well spacing, completions design, and development planning (McKinsey & Company, 2020). This is particularly critical as E&P companies continue to assume isotropic subsurface geology, resulting in frac interference, parent-child phenomena, and overall marginal field development.
Hart Energy (2020) further emphasizes a necessity for optimal development and successful experimentation that is technology driven, involving technical managers, engineers, and geoscientists to identify transformation opportunities going forward. That said, SciCat® has developed proprietary and award winning seismic driven technology that measures in-situ 3D minimum horizontal stress which is the key rock parameter that governs hydraulic fracture stimulation of tight oil and gas formations.
Experience
After 20 years in the oil and gas E&P industry, Dr. Michael Shoemaker decided to change directions in early 2020, and share his passion and expertise by helping others, so he started SciCat®. Michael is a proven oil and gas finder in both unconventional and conventional plays worldwide with extensive Permian Basin experience.
SciCat's innovative technology and workflow were recently peer-reviewed and published in The Leading Edge (2019), and has been presented at numerous venues (2019) including URTeC, Permian Basin Completions Congress, GSH, SPE Permian, PBGS, and WTGS.
Dr. Shoemaker holds a PhD in Geophysics from the Missouri University of Science and Technology (formally the University of Missouri-Rolla), has authored over 60 publications and is the recipient of the 2020 Levorsen Memorial Award for innovation in subsurface exploration.