Stress Field and Natural Fracture System in Polish Shale Belt Based on Borehole Images

2017 ◽  
Author(s):  
J. Zacharski ◽  
B. Hansen
Keyword(s):  
Stress Field ◽  
Natural Fracture ◽  
Fracture System

Application of Research of the Relationship between Ground Stress and Fractures in the Trajectory Optimization of Horizontal Wells

2013 ◽  
Vol 765-767 ◽  
pp. 300-306
Author(s):  
Hui Zhang ◽  
Fang Jun Ou ◽  
Guo Qing Yin ◽  
Jing Bing Yi ◽  
Fang Yuan ◽  
...  
Keyword(s):  
Stress State ◽  
Stress Field ◽  
Trajectory Optimization ◽  
Horizontal Wells ◽  
Wellbore Stability ◽  
Natural Fracture ◽  
Fracture System ◽  
Well Trajectory ◽  
The Stability ◽  
The Relationship

From the perspective of improving single well production and wellbore stability, stress field and natural fractures are the factors which have to be taken into account in the development of horizontal wells of the complex carbonate oil and gas fields in Kuqa piedmont and platform-basin transitional area. On the one hand, as the present stress field is the key factor to control fracture permeability, the trajectory of horizontal wells should pass through fracture system with good permeability as much as possible, being conducive to the effective stimulation of the reservoir. On the other hand, at the state of specific stress, the stability of well trajectory varies with directions. Therefore, before drilling horizontal wells, it is necessary to fully analyze the quantitative relationship between the present stress state and natural fracture occurrence and mechanical characteristics, etc., to optimize and determine a well trajectory conducive to high yield and wellbore stability. In this study, firstly, the fundamental principles for evaluating the present stress state and analyzing the relationship between the stress and fractures were described. Then based on the relationship between them, the occurrence and longitudinal positions of permeability fractures were analyzed. Apart from that, the stability index and fracture opening pressure distribution of wells in different directions at given stress state and fracture system were also analyzed. Finally, the optimization scheme for trajectory of horizontal wells under complex conditions was discussed with three aspects taken into account, i.e. best drilling in permeability fractures, wellbore stability and drilled reservoir stimulation.

A Novel Workflow for Optimizing Well Placement Under Geomechanical Constraints: A Case Study

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Cheng An ◽  
Peng Zhang ◽  
Amanveer Wesley ◽  
Gaetan Bardy ◽  
Kevin Hall ◽  
...  
Keyword(s):  
Stress Field ◽  
Three Dimensional ◽  
Production Performance ◽  
Natural Fracture ◽  
Petrophysical Properties ◽  
Reservoir Model ◽  
Differential Stress ◽  
Well Placement ◽  
Flow Simulations

Abstract A novel workflow to optimize well placement using geomechanical constraints is introduced to maximize production performance, reduce excessive simulation runs, and minimize drilling constraints by considering the local stress field and the petrophysical properties in a given reservoir. A case study is presented for optimization of horizontal well placement in the Monterey Formation of Miocene Age in California. First, a three-dimensional reservoir model of formation pressure, in situ stresses, petrophysical and rock properties were built from available petrophysical and well log data. Second, numerical modeling using material point method (MPM) was applied to generate the differential stress field, taking into consideration a three-dimensional natural fracture network in the reservoir model. Third, an optimization algorithm which incorporates petrophysical properties, natural fracture distribution, differential stresses, and mechanical stability was used to identify the best candidate locations for well placement. Finally, flow simulations were conducted to segregate each candidate location where both natural and hydraulic fractures were considered. Statistical methods identify optimal well positions in areas with low differential stress, high porosity, and high permeability. Several candidate locations for well placement were selected and flow simulations were conducted. A comparison of the production performance between the best candidates and other randomly selected well configurations indicates that the workflow can effectively recognize scenarios of optimum well placement. The proposed workflow provides practical insight on well placement optimization by reducing the number of required reservoir simulation runs and maximizing the hydrocarbon recovery.

THE OTWAY BASIN: EARLY CRETACEOUS RIFTING TO NEOGENE INVERSION

1995 ◽  
Vol 35 (1) ◽  
pp. 494 ◽  
Author(s):  
A.J. Buffin ◽  
A.J. Sutherland ◽  
J.A. Gorski
Keyword(s):  
Stress Field ◽  
Normal Fault ◽  
Horizontal Wells ◽  
Horizontal Stress ◽  
Natural Fracture ◽  
Water Flooding ◽  
Hydraulic Fractures ◽  
Vertical Wells ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress

Borehole breakouts and hydraulic fractures in­ferred from dipmeter and formation microscanner logs indicate that the minimum horizontal stress (σh) is oriented 035°N in the South Australian sector of the Otway Basin. Density and sonic check-shot log data indicate that vertical stress (σv) increases from approximately 20 MPa at a depth of one km to 44 MPa at two km and 68 MPa at three km. Assum­ing a normal fault condition (i.e. σy > σH > σh), the magnitude of σh is 75 per cent of the magnitude of the maximum horizontal stress (σH), and the magni­tude of σH is close to that of av. Sonic velocity compaction trends for shales suggest that pore pressure is generally near hydrostatic in the Otway Basin.Knowledge of the contemporary stress field has a number of implications for hydrocarbon produc­tion and exploration in the basin. Wellbore quality in vertical wells may be improved (breakouts sup­pressed) by increasing the mud weight to a level below that which induces hydraulic fracture, or other drilling problems related to excessive mud weight. Horizontal wells drilled in the σh direction (035°N/215°N) should be more stable than those drilled in the σH direction, and indeed than vertical wells. In any EOR operations where water flooding promotes hydraulic fracturing, injectors should be aligned in the aH (125°N/305°N) direction, and off­set from producers in the orthogonal σh direction. Any deviated/horizontal wells targeting the frac­tured basement play should be oriented in the σh (035°N/215°N) direction to maximise intersection with this open, natural fracture trend. Hydrocar­bon recovery in wells deviated towards 035°N/215°N may also be enhanced by inducing multiple hydrau­lic fractures along the wellbore.Considering exploration-related issues, faults following the dominant structural trend, sub-paral­lel to σH orientation, are the most prone to be non-sealing during any episodic build-up of pore pres­sure. Pre-existing vertical faults striking 080-095°N and 155-170°N are the most prone to at least a component of strike-slip reactivation within the contemporary stress field.

Stimulation of the natural fracture system by graded proppant injection

2013 ◽  
Vol 111 ◽  
pp. 71-77 ◽  
Author(s):  
Aditya Khanna ◽  
Alireza Keshavarz ◽  
Kate Mobbs ◽  
Michael Davis ◽  
Pavel Bedrikovetsky
Keyword(s):  
Natural Fracture ◽  
Fracture System ◽  
Stimulation Of

Hydraulic Fracturing Technology Design in Natural Fracture Reservoirs

2014 ◽  
Vol 941-944 ◽  
pp. 2521-2524
Author(s):  
Bo Cai ◽  
Yun Hong Ding ◽  
Zhou Qi Cui ◽  
Zhen Zhou Yang ◽  
Hua Shen
Keyword(s):  
Numerical Simulation ◽  
Hydraulic Fracturing ◽  
Pore Volume ◽  
Igneous Rock ◽  
Natural Fracture ◽  
Low Permeability ◽  
Fracture System ◽  
The Core ◽  
Limited Scale ◽  
Low Permeability Reservoirs

Nowadays, hydraulic fracturing has become the mainly treatment in low permeability reservoirs, but the hydraulic fracturing design technology in different reservoirs still use common methods. Natural fracture reservoirs mainly include granite reservoir, basalt reservoir and igneous rock reservoir which its hydrocarbon pore volume is fracture system. As the existing of natural fracture, hydraulic fracturing treatment always counting some problems, such as difficult sand pumping, easily screen-out and limited scale. In this paper, from the point of the reservoir characteristics, the mainly problems were analyzed and the corresponding methods were put forward .the core technique in this kind reservoir include communicating the distance nature fracture and meanwhile protecting the conductivity nature fracture. Production can reach 90% from natural fractures using numerical simulation.

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