An Integrated Geomechanics and Real Time Pore Pressure Approach helps to Successfully Drill the First Horizontal Well Along the Minimum Horizontal Stress Direction in Tight Sandstone Formations

2016 ◽  
Author(s):  
Vladimir Vasquez ◽  
Stephane Le Roux ◽  
Julien Heylen ◽  
Hassan Eissa ◽  
Akram Almazaqei
Keyword(s):  
Real Time ◽  
Pore Pressure ◽  
Horizontal Well ◽  
Horizontal Stress ◽  
Tight Sandstone ◽  
Stress Direction ◽  
Minimum Horizontal Stress

Utilizing Microseismic to Monitor Fracture Geometry in a Horizontal Well in a Tight Sandstone Formation

2021 ◽  
Author(s):  
Abu M. Sani ◽  
Hatim S. AlQasim ◽  
Rayan A. Alidi
Keyword(s):  
Horizontal Well ◽  
Fracture Propagation ◽  
Horizontal Stress ◽  
Height Growth ◽  
Tight Sandstone ◽  
Fracture Geometry ◽  
Fracture Length ◽  
Sandstone Formation ◽  
Fracture Height ◽  
Maximum Horizontal Stress

Abstract This paper presents the use of real-time microseismic (MS) monitoring to understand hydraulic fracturing of a horizontal well drilled in the minimum stress direction within a high-temperature high-pressure (HTHP) tight sandstone formation. The well achieved a reservoir contact of more than 3,500 ft. Careful planning of the monitoring well and treatment well setup enabled capture of high quality MS events resulting in useful information on the regional maximum horizontal stress and offers an understanding of the fracture geometry with respect to clusters and stage spacing in relation to fracture propagation and growth. The maximum horizontal stress based on MS events was found to be different from the expected value with fracture azimuth off by more than 25 degree among the stages. Transverse fracture propagation was observed with overlapping MS events across stages. Upward fracture height growth was dominant in tighter stages. MS fracture length and height in excess of 500 ft and 100 ft, respectively, were created for most of the stages resulting in stimulated volumes that are high. Bigger fracture jobs yielded longer fracture length and were more confined in height growth. MS events fracture lengths and heights were found to be on average 1.36 and 1.30 times, respectively, to those of pressure-match.

Horizontal Water Injection Wells: Injectivity and Containment of Injection-Induced Fractures

2021 ◽  
Author(s):  
Jongsoo Hwang ◽  
Mukul Sharma ◽  
Maria-Magdalena Chiotoroiu ◽  
Torsten Clemens
Keyword(s):  
Horizontal Well ◽  
Water Injection ◽  
Fracture Initiation ◽  
Horizontal Stress ◽  
Operating Conditions ◽  
Critical Factors ◽  
Injection Wells ◽  
Stress Direction ◽  
Maximum Horizontal Stress ◽  
Transverse Fractures

Abstract Horizontal water injection wells have the capacity to inject larger volumes of water and have a smaller surface footprint than vertical wells. We present a new quantitative analysis on horizontal well injectivity, injection scheme (matrix vs. fracturing), and fracture containment. To precisely predict injector performance and delineate safe operating conditions, we simulate particle plugging, thermo-poro-elastic stress changes, thermal convection and conduction and fracture growth/containment in reservoirs with multiple layers. Simulation results show that matrix injection in horizontal wells continues over a longer time than vertical injectors as the particle deposition occurs slowly on the larger surface area of horizontal wellbores. At the same time, heat loss occurs uniformly over a longer wellbore length to cause less thermal stress reduction and delay fracture initiation. As a result, the horizontal well length and the injection rates are critical factors that control fracture initiation and long-term injectivity of horizontal injectors. To predict fracture containment accurately, thermal conduction in the caprock and associated thermal stresses are found to be critical factors. We show that ignoring these factors underestimates fracture height growth. Based on our simulation analysis, we suggest strategies to maintain high injectivity and delay fracture initiation by controlling the injection rate, temperature, and water quality. We also provide several methods to design horizontal water injectors to improve fracture containment considering wellbore orientation relative to the local stress orientations. Well placement in the local maximum horizontal stress direction induces longitudinal fractures with better containment and less fracture turning than transverse fractures. When the well is drilled perpendicular to the maximum horizontal stress direction, the initiation of transverse fractures is delayed compared with the longitudinal case. Flow control devices are recommended to segment the flow rate and the wellbore. This helps to ensure uniform water placement and helps to keep the fractures contained.

Predrill pore-pressure prediction and pore pressure and fluid loss monitoring during drilling: A case study for a deepwater subsalt Gulf of Mexico well and discussion on fracture gradient, fluid losses, and wellbore breathing

2014 ◽  
Vol 2 (1) ◽  
pp. SB45-SB55 ◽  
Author(s):  
Fernando Enrique Ziegler ◽  
John F. Jones
Keyword(s):  
Gulf Of Mexico ◽  
Pore Pressure ◽  
Horizontal Stress ◽  
Fluid Loss ◽  
Pressure Profiles ◽  
Pore Pressure Prediction ◽  
Fracture Gradient ◽  
Minimum Horizontal Stress ◽  
Fluid Losses

In this case study, the overburden, pore-pressure, and fracture gradients are calculated for several nearby analog wells and subsequently used to generate a predrill pore-pressure prediction for the deepwater subsalt Gulf of Mexico well, Flying Dutchman, located in Green Canyon 511 no. 1 (OCS-G 22971). Two key analog wells penetrated the lower Miocene and have sufficient data to generate pore-pressure profiles. Subsequently, the predrill pore-pressure prediction is found to be in good agreement with the pore pressure estimated from well logs while drilling. During the drilling phase of the Flying Dutchman well, two zones of significant fluid loss and wellbore breathing were encountered and are evaluated as a means of determining the formation types where they are most likely to occur, as well as their related minimum horizontal stress and fracture gradient.

A MODIFIED FRACTURE GRADIENT RELATION AND ITS APPLICATION TO EAST TEXAS AND THE TIMOR SEA

1997 ◽  
Vol 37 (1) ◽  
pp. 536
Author(s):  
R.R. Hillis ◽  
D.G. Crosby ◽  
A.K. Khurana
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Poisson’S Ratio ◽  
Horizontal Stress ◽  
Tectonic Stress ◽  
Poisson's Ratio ◽  
East Texas ◽  
Timor Sea ◽  
Fracture Gradient ◽  
Minimum Horizontal Stress

Theoretical fracture gradient relations are generally based on the assumption that the sedimentary sequence behaves elastically under conditions of lateral constraint. Hence the minimum horizontal stress (σhmin) is given by: where V is Poisson's ratio, σv is overburden stress, pp is pore pressure, and at is far -field tectonic stress. In driling practice, fracture initiation, or leak -off pressures, which are related to σhmin are most commonly predicted by the application of empirical stress /depth relations such as that proposed for offshore Western Australia by Vuckovic (1989): Leak -off pressure (psi) = 0.197D1145, where D is depth in feet. A modified form of the uniaxial elastic relation for the prediction of σhmin is proposed, such that: where the constants c and d are straight line regression constants derived from cross -plotting effective minimum horizontal stress and effective vertical stress. This relation, as opposed to previous empirical approaches to fracture gradient /σhmin determination, yields regression coefficients of physical significance: c represents the average Poisson's ratio term, v /(1 -v), and d represents an estimate of the tectonic (and inelastic) component of the minimum horizontal stress. This application of the modified fracture gradient relation, termed the effective stress cross -plot method, is tested successfully against published data from experimental wells in the East Texas Basin where independent estimates of Poisson's ratio are available. Leak -off pressures have been compiled from 61 wells in the Timor Sea. Leak -off pressures in the Timor Sea are somewhat lower than predicted by Vuckovic's (1989) stress /depth relation for offshore Western Australia, and a new, empirical stress /depth relation, which better fits the Timor Sea data is proposed: The effective stress cross -plot method is also applied to the Timor Sea data, yielding: Detailed pore pressure data were not available for the Timor Sea data -set and the effective stress cross -plot method does not fit the observed data any better than the new empirical stress /depth relation. However, the regression constants suggest an average Poisson's ratio of 0.26 and a relatively insignificant tectonic stress of 1 MPa for the Timor Sea.

Integrated 3D geomechanical modeling and its application for well planning in Bantumilli South area, Krishna-Godavari Basin, India

2020 ◽  
Vol 39 (3) ◽  
pp. 182-187
Author(s):  
Soumen Deshmukh ◽  
Rajesh Sharma ◽  
Manisha Chaudhary ◽  
Harilal
Keyword(s):  
Pore Pressure ◽  
Elastic Properties ◽  
Horizontal Stress ◽  
Seismic Inversion ◽  
Geomechanical Properties ◽  
Fracture Pressure ◽  
3D Geomechanical Model ◽  
Weight Window ◽  
Minimum Horizontal Stress ◽  
Godavari Basin

Complex geologic structure, a heterogeneous reservoir, and complications related to high pressure during drilling necessitate carrying out geomechanical modeling to understand the physical properties of rocks and fluids present within the Early Cretaceous synrift sequence in the Bantumilli South area of the Krishna-Godavari Basin in India. Reservoirs within the synrift sequence exhibit low permeability and high pore pressure. Identification of safe mud-weight window zones is critical for safe drilling of wells in this part of the basin. A detailed workflow for building a robust 3D geomechanical model and its applications to well planning and hydraulic fracturing are presented. Elastic properties of the reservoirs were estimated by prestack seismic inversion. Elastic properties and pore pressure volumes were used to simulate the 3D stress field. The maximum horizontal stress direction is observed to be 130°N ± 5°, i.e., northwest to southeast, and estimated fracture pressure (minimum horizontal stress) values range between 10,000 and 14,200 psi within the synrift sequence. The study has shown that the Cretaceous section of the reservoir has narrow mud-weight window zones. These zones are governed mainly by a high pore pressure regime in the reservoirs. Additionally, deep-seated basement faults have played an important role in the compartmentalization of the reservoir in terms of geomechanical properties.

scholarly journals 4D Finite element modeling of stress distribution in depleted reservoir of south Iraq oilfield

2021 ◽  
Author(s):  
Raed H. Allawi ◽  
Mohammed S. Al-Jawad
Keyword(s):  
Stress Distribution ◽  
Pore Pressure ◽  
Horizontal Stress ◽  
Oil Field ◽  
Rock Properties ◽  
Target Area ◽  
Compression Tests ◽  
Fracture Pressure ◽  
Weight Window ◽  
Minimum Horizontal Stress

AbstractThe harvest of hydrocarbon from the depleted reservoir is crucial during field development. Therefore, drilling operations in the depleted reservoir faced several problems like partial and total lost circulation. Continuing production without an active water drive or water injection to support reservoir pressure will decrease the pore and fracture pressure. Moreover, this depletion will affect the distribution of stress and change the mud weight window. This study focused on vertical stress, maximum and minimum horizontal stress redistributions in the depleted reservoirs due to decreases in pore pressure and, consequently, the effect on the mud weight window. 1D and 4D robust geomechanical models are built based on all available data in a mature oil field. The 1D model was used to estimate all mechanical rock properties, stress, and pore pressure. The minimum and maximum horizontal stress were determined using the poroelastic horizontal strain model. Furthermore, the mechanical properties were calibrated using drained triaxial and uniaxial compression tests. The pore pressure was tested using modular dynamic tester log MDT. The Mohr–Coulomb model was applied in the 4D model to calculate the stress distribution in the depleted reservoir. According to study wells, the target area has been classified into four main groups in Mishrif reservoir based on depletion: highly, moderately, slightly, and no depleted region. Also, the results showed that the units had been classified into three main categories based on depletion state (from above to low depleted): L1.1, L1.2, and M1. The mean average reduction in minimum horizontal stress magnitude was 322 psi for L1.1, 183.86 psi for L1.2, and 115.56 psi for M1. Thus, the lower limit of fracture pressure dropped to a high value in L1.1, which is considered a weak point. As a result of changing horizontal stress, the mud weight window became narrow.

scholarly journals Experimental Investigation on Propagation Behavior of Hydraulic Fractures in Coal Seam during Refracturing

Geofluids ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Xun Sun ◽  
Shicheng Zhang ◽  
Xinfang Ma ◽  
Yushi Zou ◽  
Guanyu Lin
Keyword(s):  
Pore Pressure ◽  
Horizontal Stress ◽  
Stress Change ◽  
Hydraulic Fractures ◽  
Coal Seams ◽  
Initiation And Propagation ◽  
Hf Propagation ◽  
Minimum Horizontal Stress ◽  
Maximum Horizontal Stress ◽  
Study Laboratory

Refracturing is an effective technology for reinstituting a percolation path and improving the fracture conductivity in coal measure strata. Hydraulic fracture (HF) propagation is complicated due to the presence of cleats and stress change caused by pore pressure changes. Many scholars have studied HF propagation in the initial fracturing of coal, but the refracturing in coal seams is rarely mentioned. In this study, laboratory refracturing experiments were conducted on large natural coal specimens under various triaxial stress states to investigate the propagation of HFs in coal seams. The mechanical properties of coal were tested before refracturing. The maximum and the minimum horizontal principal stresses are inverted to simulate the stress change caused by the production and pore pressure reduction of the stress condition after initial fracturing. Experimental results showed three different types of HF initiation and propagation during refracturing: (1) under low horizontal stress differences (0-2 MPa), HF propagated along the cleats, and no new HFs were formed on the walls of the initial HFs regardless of changes in the horizontal stress; (2) under high horizontal stress differences (4–8 MPa) with no stress inversion, a major HF was initiated parallel to the orientation of maximum horizontal stress during initial fracturing; new branches propagated along cleats in the orientation of the minimum horizontal stress during refracturing; and (3) under high horizontal stress differences (4–8 MPa) with maximum and minimum horizontal stress inversions, the main HF formed along the orientation of the maximum horizontal stress, and a new HF perpendicular to the initial HF was formed during refracturing. Multiple factors affect fracture morphology during refracturing. Cleats affect the HF growth path and the creation of new branches. The in situ stress determines the initiation and propagation of new HFs.

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