Author : Chao Gao (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (133 download)
Book Synopsis A Coupled Geomechanics and Reservoir Simulator and Its Application to Reservoir Development Strategies by : Chao Gao (Ph. D.)
Download or read book A Coupled Geomechanics and Reservoir Simulator and Its Application to Reservoir Development Strategies written by Chao Gao (Ph. D.) and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new Coupled Geomechanics and Reservoir Simulator, CGRS, and a wellbore stability model, WSM, are utilized to provide dynamic infill drilling strategies - where to drill, when to drill and how to drill - that greatly improve upon the traditional constant stress path method. The stress path, defined as the ratio of the change of far-field horizontal stress to change of pore pressure, has a profound influence on wellbore stability while drilling in a depleted reservoir. Based on the common assumptions of uniaxial strain and homogenous depletion, the traditional analytical stress path solution is a function of Biot's coefficient and Poisson's ratio. Pore pressure depletion, however, is location and time dependent, not homogeneous. Thus, the objective of this study is to analyze the wellbore stability of infill wells with a coupled geomechanics and reservoir simulator. Two wellbore stability models, first a conventional wellbore stability model (CWSM) and second a Coupled Geomechanics and Reservoir Simulator Wellbore Stability Model (CGRS-WSM), were developed. For CWSM, the analytical stress path solution is applied to get updated far-field horizontal stresses. CGRS-WSM, however, does not require changes in far-field horizontal stress with pressure depletion. Rather, CGRS gives the stress field of the whole reservoir, and those stress components at a specific point in Cartesian coordinates are used directly in CGRS-WSM to calculate the mud weight window. For CGRS, an in-house coupled geomechanics and reservoir simulator is developed that considers lateral displacements and inhomogeneous depletion of the reservoir. In addition, an Abaqus model is also developed to analyze the influence of plasticity and stress arching on pore pressure and stress change during depletion, which are used in CGRS-WSM to investigate wellbore stability. Different shear failure criteria are utilized in a new CGRS wellbore stability model. The upper bounds of shear failure are given by Drucker-Prager Inscribes and Griffith Theory, while the lower bound is given by Drucker-Prager Circumscribe. Several case studies for drilling in a depleted reservoir compare CWSM with CGRS-WSM. There is a significant difference in the two maximum mud weights, with operational consequences, for example, as related to potential lost circulation problems. For some examples, the narrower mud weight from CGRS-WSM, as compared to CWSM, is a more realistic unsafe region warning. CGRS-WSM can quantify the influence of azimuth on the minimum and the maximum mud weight during the depletion when initial maximum horizontal stress equals minimum horizontal stress. In addition, CGRS-WSM can give the output of a location-dependent mud weight map for the entire reservoir. Neither of the above two functions can be realized by a conventional wellbore stability model. The CGRS-WSM in this work is a significant step in drilling infill wells in depleted zones, owing to its ability to quantify horizontal displacements, inhomogeneous depletion, plasticity, and stress arching, which cannot be done with the traditional analytical stress path procedure. Moreover, the connection of a coupled geomechanics and reservoir simulator with a wellbore stability simulator provides dynamic information useful to quantify where to drill, when to drill and how to drill. This new model can be used to investigate 'what if' scenarios, parameter sensitivity studies, case study reviews, and previously drilled well critiques