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This session will set the stage for what we can tell today between wells and what we want to be able to do in the future. The group will brainstorm at least two circumstances to initially attempt to determine the state of industry and identify topics for closing gaps in what we can know today. The group will frame our understanding in technical and commercial terms to highlight choices to be made, potential shortcomings, and aspects in regards to perfection and steps to potentially get there. The initial brainstorm will be blended topically into the remaining agenda as an initiation point of discussion. The information obtained from many oilfield measurements fall at the ends of a spectrum – as they are either obtained by probing or imaging the near-wellbore region at high vertical resolution or they illuminate large reservoir volumes at poor vertical resolution; and may be more sensitive to rock properties than to fluid behavior in the reservoir.
This work focuses on the development of specific methodologies to support managed-pressure-dilling (MPD) operations implemented on real-time diagnostic software. In hydraulic fracturing, the use of diagnostic-fracture-injection tests (DFITs) can provide valuable information. This paper offers an analytical model for estimating the transient temperature at a given depth and timestep, for computing the BHP. To achieve optimal production from unconventional reservoirs, it is useful to determine the permeability, pore pressure, and state of stress of rock strata. This paper attempts to describe some of the common problems and to help prevent some common errors often observed in diagnostic fracture injection tests (DFITs) execution and analysis.
Petroleum geomechanics is defined as the interaction between the evolving earth stresses and the overburden and reservoir rock mechanical properties. A comprehensive understanding of rock mechanical behaviour is key to successful field appraisal and development. For example, 70% of the world’s oil and gas reserves are contained in reservoirs where rock failure and sand production will become a problem at some point. Wellbore stability issues have been estimated to cost the industry USD 8 billion annually. Around 80%–90% of data comes from “traditional” core and log petrophysics, but the importance of data quality control and a rigorous and consistent petrophysical interpretation is often overlooked by well construction and production engineers.
The course addresses the holistic sand management strategy implementation from geomechanics perspectives, through evaluation and implementation of appropriate solutions for minimisation of well costs and maximisation of reservoir productivity. It will look at the inter-relationships between geomechanics and operations, application of geomechanics in relation to sand production and completions, and show how geomechanics can be best applied to provide maximum value in sand management and life-of-well and field operations. The course comprehensively covers geomechanics and operational-related sand production mechanisms, laboratory simulations of sand production to provide measurement data for model calibration and validation, state-of-the-art analytical and 4-D numerical sanding predictive methodologies for life-of-well and field including scale effect, rock strength properties reduction associated with water-cut and estimation of cumulative sand volume and rate of sand production, and optimal mitigation and management of sand production taking into consideration the feasibility of deferment or elimination of sand control installation. The course is illustrated with field examples. Application of geomechanics in relation to sand production and completions in order to provide maximum value in sand management and life-of-well and field operations.
Geomechanics for Conventional and Unconventional Resources Course Description Geomechanics is playing an increasingly important role in developing conventional and unconventional resources (Coal Seam Gas and Shale Gas). This course will help you understand the fundamentals of geomechanics and its applications to conventional and unconventional reservoirs (CSG and Shale Gas) which will enable better field development decisions. You will learn the essential data required to construct a 1D MEM (1 Dimensional Mechanical Earth Model), Rock Testing planning for a geomechanics study, calibration of the model and application to drilling, sanding and hydraulic fracturing in conventional and unconventional reservoirs. You will also learn about data requirement and workflow for constructing a 3D MEM and its applications with case studies. Daily Activities Agenda (pdf) Learning Level Intermediate Course Length 1 Day Why Attend This one day short course is intended to cover the fundamentals of geomechanics and its applications in conventional and unconventional resources (Coal Seam Gas and Shale Gas).
DFIT – The Unconventional Well Test course will review the theory of fracture-injection/falloff testing, the design of DFITs, and interpretation of DFIT data using both straight-line and type-curve methods. Design and interpretation methods will be illustrated with North American field examples, including horizontal and vertical well DFITs in unconventional reservoirs. Additionally, field case studies will be included to show how DFIT interpretations can be used in production data analysis of wells producing from unconventional reservoirs. Attendees will learn the basic theoretical foundation of diagnostic fracture-injection/falloff test implementation and analysis along with obtaining guidelines for implementing DFIT in field operations. Field guidelines for absolute beginners are provided.
Wellbore instability has been experienced in areas of the Marcellus Shale and can become particularly troublesome in the superlaterals that are becoming more prevalent in that play. Often the instability while drilling these very long lateral wells is minimal; problems are more likely to occur while tripping out after reaching TD. The most common instability events when pulling out of the hole appear to be tight hole, pack-off and stuck pipe. These problems often worsen with time, indicating there is some time-dependence to the failure mechanism.
In order to develop effective mitigation strategies to combat the instability, it is imperative that the failure mechanism be correctly identified. Previous publications (Kowan and Ong, 2016; Addis et al. 2016; Riley et al. 2012) have suggested that bedding planes may play a role in some of the drilling problems experienced in the Marcellus Shale. In this paper, we will present a case study from the Marcellus that shows conclusive proof of weak bedding plane failure along a lateral well, where thousands of feet of anisotropic failure were captured with a LWD image log.
This image provided confirmation of the presence and failure of weak bedding planes in the Marcellus Shale. The image was also used to validate an existing geomechanical model for the area and gave the operator more confidence in the mitigation strategies developed from that geomechanical model, which had been based on the assumption that weak bedding was contributing to difficulty experienced on multiple lateral wells when tripping out of the hole.
This case study will begin with an overview of the geomechanical model, including the drilling history, stress/pore pressure model and rock properties. Next, some highlights from the image log, showing anisotropic bedding plane failure, will be featured as well as a comparison of the image to the geomechanical model. This case study will conclude with a review of proposed mitigation strategies that could be implemented by the operator to limit the risks posed by weak beds and minimize instability, when drilling laterals in this area, or similarly complex areas, of the Marcellus Shale.
M. Faskhoodi, Majid (Schlumberger) | Damani, Akash (Schlumberger) | Kanneganti, Kousic (Schlumberger) | Zaluski, Wade (Schlumberger) | Ibelegbu, Charles (Schlumberger) | Qiuguo, Li (Schlumberger) | Xu, Cindy (Schlumberger) | Mukisa, Herman (Schlumberger) | Ali Lahmar, Hakima (Schlumberger) | Andjelkovic, Dragan (Schlumberger) | Perez Michi, Oscar (Schlumberger) | Zhmodik, Alexey (Schlumberger) | Rivero, Jose A. (Schlumberger) | Ameuri, Raouf (Schlumberger)
To unlock unconventional reservoirs for optimum production, maximum contact with the reservoir is required; however, excessively dense well placement and hydraulic fractures interconnection is a source of well-to-well interaction which impairs production significantly. The first step to have successful and effective well completion is to understand the characteristics of the hydraulic fractures and how they propagate in reservoir. This paper demonstrates an integrated approach with a field example in the Montney formation for how modern modeling techniques were used to understand and optimize hydraulic fracture parameters in unconventional reservoir.
Advanced logs from vertical wells and 3D-seismic were used to build an integrated geological model. Lamination index analysis was performed, using borehole imagery data to account for interaction of hydraulic fracture with vertically segregated rock fabric and to provide additional control on hydraulic fracture height growth during modeling process. A non-uniform Discrete-Fracture-Network (DFN) model was constructed. 3D-geo-mechanical model was built and initialized, using sonic log and seismic data.
Fluid friction and leak-off was calibrated, using treatment pressure and DFIT data. Hydraulic fracture modeling was done for pad consists of 6 horizontal wells with multi-stage fracturing treatments, by utilizing actual pumped schedules and calibrating it against microseismic data.
High-stress anisotropy led to planar hydraulic fractures despite presence of natural fractures in area. Fracturing sequence, i.e., effect of stress shadow, is seen to have major impact on hydraulic fracture geometry and propped surface area. Heatmaps were generated to estimate average stimulated and propped rock volume in section. It was also observed that rock fabrics, i.e., natural fracture and lamination has considerable impact on propagation of hydraulic fracture. Multiple realizations of natural fracture and lamination distribution were generated and used as an input in modeling process.
High resolution unstructured simulation grids were generated to capture fracture dimensions and conductivities, as well as track propped and unpropped regions in stimulation network. Dynamic model was constructed and calibrated against historical production data. History matched model was then used as predictive tool for pad development optimization and to evaluate parent-child interaction in depleted environment.
High angle S-shaped and high displacement L-shaped well profiles are preferred now-a-days in Balimara field located in the northeast region of India. Main targets are the deep Clastic reservoirs of Oligocene age. Major events reported are while drilling against dipping formations with differential stuck pipe situations with variety of drilling complications in the unstable formations owing to shales in Tipam sandstone and thin sections of coal and shale alteration in oil bearing Barail sandstone formation. The substantial risk of wellbore instability in accessing the reservoirs with lateral variation in pore pressure threatened the commercial success of the project. This paper elaborates how geomechanical information along with BHA design and chemicals was integrated into the decision-making process during well design and drilling operations to avoid wellbore instability issues.
Wellbore stability analysis through Mechanical Earth Model was conducted using estimated state of stress and mechanical properties of the overburden and reservoirs. The model incorporated data from several sources including geophysical logs, leak-off tests, advanced sonic far field profile and drilling records collected from the earlier wells. Examination of the deviated well bore profiles suggested occurrence of ledges due to lower mud weight and improper drilling parameters while drilling alternate layers of sand, shale and coal in Barail formation. Horizontal stress contrast increases in Barail formation supporting the need of higher mud weight with increased well deviation towards specific azimuth.
The integrated geomechanical analysis provided key information: The 9 5/8" casing shoe should be set at shale layer of Tipam Bottom to isolate upper differential sticking prone sandstone layers with Barail Argillaceous sequence. This will help to drill 12.25-inch hole with 9.6 ppg-9.8 ppg only. Shale layers at Tipam bottom require 10.0-10.5 ppg, while Barail shale requires 10.5 ppg-11.0 ppg for vertical well. When the well deviation increases up to 30deg, mud weight requirement rises to 11.2 ppg-11.8 ppg. Based on analysis, the mud weight at the start of 8.5inch section was raised sufficiently to 10.5 ppg to avoid the hole collapse experienced in the earlier lower angle wells. Later, continuous review of torque and drag along with cutting analysis helped to raise mud weight up to 11.0 ppg till well TD. As a result, lower UCS shale and coal layers are drilled with minimal shear failure and improved hole condition. However, changes to the mud system were needed to limit fluid loss and avoid differential sticking across the sandstone. For deviated section, rotary BHA has been used to improve hole trajectory vs. planned with lesser ledges. Downhole hydraulics has been maintained with proper flow rate and rpm to main hole cleaning. The new well engineered with the integrated geomechanics information has been drilled from surface to extended TD while saving 15 rig days.