A Practical Workflow for Offshore Hydraulic Fracturing Modelling: Focusing on Southern North Sea

Abstract

The high prices of energy encourage investments in oil and gas research and development leading to new or improved technologies to recover more hydrocarbons from resources and re-evaluate the reserves. As a result of such technological developments and experience of job practices, hydraulic fracturing techniques have improved significantly in terms of designing and execution and this, at the same time, has made the process much more complicated. This paper suggests a practical multi-disciplinary workflow for hydraulic fracturing modelling mainly in tight gas sandstone reservoirs.Hydraulic fracturing stimulations in costly environments such as the Southern North Sea require deeper insight into the chemistry and mechanics of the process, characteristics of the formation, and most importantly, the interactions during and after the stimulation job. Different sources of information and analysis such as seismic, reservoir static modelling, initial geomechanical modelling, initial hydraulic fracturing study, fracture initiation point analysis, 1-dimensional (vertical) stress modelling per frac, mini-frac, mainfrac, flowback analysis, well test analysis, and reservoir dynamic modelling are discussed in this paper. The key data cross checks are recognised and lessons learnt from industry are also incorporated to highlight the possible outcomes of different decisions.Having more information, particularly from different disciplines, can be more productive only if a comprehensive guideline explains the essential elements of the required studies and illustrates their interrelations. This workflow has been the reference of a validated study for a multi-fracced tight gas sandstone reservoir in the Southern North Sea. The workflow has been deployed to organise and recognise the key elements that control the performance of hydraulically fractured wells in a heterogeneous environment. From the workflow, a thorough examination and analysis of available data were performed and fed into the static and dynamic models. As a result of the integrated workflow, a better understanding of the reservoir was formed and potential upside opportunities became visible.This paper highlights the importance of integrated multi-disciplinary workflow required to detect, characterise and evaluate information from the field into a product that can be used to better understand hydraulic fracturing and tight gas sandstone reservoirs.

Evaluation of heterogeneity impact on hydraulic fracturing performance

“…In this section, the details of application of the comprehensive workflow of hydraulic fracture performance analysis introduced by the authors in a previous publication (Parvizi, et al, 2015b) is presented. In this work, actual field data was acquired from an oil and gas operator with the view to evaluate the hydraulic fracture performance.…”

“…Southern North Sea (SNS) reservoirs are among the most heterogeneous reservoirs in which hydraulic fracturing has been considered for implementation. The SNS reservoirs are characterised by their more permeable layers and natural fractures as the two possible elements of heterogeneity (Parvizi, et al, 2015a) and (Parvizi, et al, 2015b). These distinctions make the fraccing designs more complicated and signify the importance of taking an integrated approach to get the most out of the available data.…”

“…In the following sections, first, the workflow introduced by the authors in a previous study (Parvizi, et al, 2015b) to analyse the hydraulic fracture performance is discussed. In that study, an integrated multidisciplinary approach was proposed for deploying the data and information available all the way from seismic interpretation to reservoir dynamic modelling to evaluate the performance of the hydraulic fracturing.…”

Modeling the Risk of Commercial Failure for Hydraulic Fracturing Projects Due to Reservoir Heterogeneity

“…In this sense, improving gas recovery from unconventional gas resources such as shale gas [1][2][3][4] and tight gas [5][6][7] reservoirs using the hydraulic fracturing technology has proved to be effective in supplying a part of the increasing global energy demand. Some examples of hydraulic fracturing applications have been reported all around the world [8][9][10][11][12]. Although the fracturing technique is now considered an essential part of the reservoir management backbone in tight/shale gas field developments, the complexities associated with the hydraulic fracturing dictate some degree of uncertainty in successful economic applications [6,[13][14][15][16].…”

Robust and Flexible Hydrocarbon Production Forecasting Considering the Heterogeneity Impact for Hydraulically Fractured Wells

“…However, since most of the homogenous and giant hydrocarbon reservoirs have been developed and produced over the last century, development of more heterogeneous and challenging oil and gas fields has become the new trend for the industry. This needs advanced approaches for capturing further complexities in production forecasting which serves as the foundation for field development decision making 20 .…”