With the production of oil and gas from the reservoir for a long period of time, pore pressure will decline from the initial value to a lower level, which narrows the safety mud weight window, and consequently, makes it easier to generate the drilling induced fracture (DIF). In this paper, a new analytical model is proposed for predicting initiation pressure and corresponding initiation mode of DIF in the pressure depleted reservoir. The effect of pore pressure decline on stress field is considered. Formation around the borehole is divided into plastic zone and elastic zone according to the geomechanical parameters, and small deformation theory is adopted in both of the plastic zone and the elastic zone. For the plastic zone, the nonlinear constitutive relationship is captured using equivalent stress and equivalent strain. In addition, excess pore pressure theory is introduced to describe the pore pressure change during the drilling process owing to the formation of mudcake on the borehole wall. Then, the stress and pore pressure distribution in these two zones and the radius of the plastic zone are obtained. Meanwhile, the theoretical formula of initiation pressure and the corresponding initiation mode of DIF are derived. The reliability of the new model is validated by comparing the obtained results with other published models and the field measured data.

References

References
1.
Feng
,
Y. C.
, and
Gray
,
K. E.
,
2016
, “
A Fracture-Mechanics-Based Model for Wellbore Strengthening Applications
,”
J. Nat. Gas. Sci. Eng.
,
29
, pp.
392
400
.
2.
Feng
,
Y. C.
, and
Gray
,
K. E.
,
2016
, “
A Parametric Study for Wellbore Strengthening
,”
J. Nat. Gas. Sci. Eng.
,
30
, pp.
350
363
.
3.
Feng
,
Y. C.
,
Jones, J. F.
, and
Gray, K. E.
,
2016
, “
A Review on Fracture-Initiation and Propagation Pressures for Lost Circulation and Wellbore Strengthening
,”
SPE Drill. Completion
,
31
(
2
), pp.
134
144
.
4.
Cao
,
C.
,
Pu, X. L.
,
Zhao, Z. G.
,
Wang, G.
, and
Du, H.
,
2018
, “
Experimental Investigation on Wellbore Strengthening Based on a Hydraulic Fracturing Apparatus
,”
ASME J. Energy Resour. Technol.
,
140
(
5
), pp.
1
8
.
5.
Salehi
,
S.
, and
Kiran
,
R.
,
2016
, “
Integrated Experimental and Analytical Wellbore Strengthening Solutions by Mud Plastering Effects
,”
ASME J. Energy Resour. Technol.
,
138
(
3
), pp.
1
7
.
6.
Hubbert
,
M. K.
, and
Willis
,
D. G.
,
1957
, “
Mechanics of Hydraulic Fracturing
,”
Trans. AIME
,
210
, pp.
153
166
.https://www.ems.psu.edu/~radovic/EME580_T1_sci1.pdf
7.
Haimson
,
B.
, and
Fairhurst
,
C.
,
1969
, “
In-Situ Stress Determination at Great Depth by Means of Hydraulic Fracturing
,”
Eleventh Symposium on Rock Mechanics,
Berkeley, CA, June 16–19.
8.
Rummel
,
F.
,
1987
, “
Fracture Mechanics Approach to Hydraulic Fracturing Stress Measurements
,”
Fracture Mechanics of Rock
,
B. K.
Atkinson
, ed., Institute of Geophysics, Ruhr University, Bochum, West Germany, pp.
217
239
.
9.
Detournay
,
E.
, and
Carbonell
,
R.
,
1997
, “
Fracture-Mechanics Analysis of the Breakdown Process in Minifracture or Leakoff Test
,”
SPE Prod. Facil.
,
12
(
3
), pp.
195
199
.
10.
Mehrabian
,
A.
,
Jamison, D. E.
, and
Teodorescu, S. G.
,
2015
, “
Geomechanics of Lost-Circulation Events and Wellbore-Strengthening Operations
,”
SPE J.
,
20
(
6
), pp.
1305
1316
.
11.
Mehrabian
,
A.
,
2016
, “
The Stability of Inclined and Fractured Wellbores
,”
SPE J.
,
21
(
5
), pp.
1518
1536
.
12.
Fallis, A.
, 2013, “
Experimental Rock Deformation-the Brittle Field
,”
J. Chem. Inf. Model.
,
53
, pp. 1689–1699.
13.
Aadnoy
,
B. S.
, and
Belayneh
,
M.
,
2004
, “
Elasto-Plastic Fracturing Model for Wellbore Stability Using Non-Penetrating Fluids
,”
J. Pet. Sci. Eng.
,
45
(
3–4
), pp.
179
192
.
14.
Boyce, G. M.
, 1988, “
A Study of Stress Determination in Rock Salt by the Method of Hydraulic Fracturing
,” California University, Berkeley, CA.
15.
Xia
,
H. W.
, and
Moore
,
I. D.
,
2006
, “
Estimation of Maximum Mud Pressure in Purely Cohesive Material During Directional Drilling
,”
Geomech. Geoeng. Int. J.
,
1
(
1
), pp.
3
11
.
16.
Wang
,
Y.
, and
Dusseault
,
M. B.
,
1991
, “
Borehole Yield and Hydraulic Fracture Initiation in Poorly Consolidated Rock Strata—Part I: Impermeable Media
,”
Int. J. Rock Mech. Min. Sci. Geomech. Abstr.
,
28
(
4
), pp.
235
246
.
17.
Wang
,
Y.
, and
Dusseault
,
M. B.
,
1991
, “
Borehole Yield and Hydraulic Fracture Initiation in Poorly Consolidated Rock Strata—Part II: Permeable Media
,”
Int. J. Rock Mech. Min. Sci. Geomech. Abstr.
,
28
(
4
), pp.
247
260
.
18.
Morita
,
N.
,
Whitfill, D. L.
,
Fedde, O. P.
, and
Levik, T. H.
,
1989
, “
Parametric Study of Sandproduction Prediction: Analytical Approach
,”
SPE Prod. Eng.
,
4
(
1
), pp.
25
33
.
19.
Papanastasiou
,
P.
,
Thiercelin, M.
,
Cook, J.
, and
Durban, D.
,
1995
, “
The Influence of Plastic Yielding on Breakdown Pressure in Hydraulic Fracturing
,” The 35th U.S. Symposium on Rock Mechanics (USRMS), Reno, Nevada, June 5–7, pp.
281
286
.
20.
Papanastasiou
,
P.
,
Cook, J.
, and
Durban, D.
,
1999
, “
Modes of Fracture Initiation in Thickwall Cylinder Experiemnts
,” The 37th U.S. Symposium on Rock Mechanics (USRMS), Vail, CO, June 7–9, pp.
333
340
.
21.
Li
,
J.
,
Qiu, Z. S.
,
Song, D. D.
,
Zhong, H. Y.
, and
Tang, Z. C.
,
2017
, “
Numerical Simulation of 3D Fracture Propagation in Wellbore Strengthening Conditions
,”
J. Pet. Sci. Eng.
,
156
, pp.
258
268
.
22.
Zhao
,
P. D.
,
Santana, C. L.
,
Feng, Y. C.
, and
Gray, K. E.
,
2017
, “
Mitigating Lost Circulation: A Numerical Assessment of Wellbore Strengthening
,”
J. Pet. Sci. Eng.
,
157
, pp.
657
670
.
23.
Hu
,
Z. X.
,
1997
,
Soil Mechanics and Environment Soil Engineering
,
Tongji University Press
,
Shanghai, China
.
24.
Biot
,
M. A.
,
1962
, “
Mechanics of Deformation and Acoustic Propagation in Porous Media
,”
J. Appl. Phys.
,
33
(
4
), pp.
1482
1498
.
25.
Kirsch
,
G.
,
1898
, “
Die Theorie Der Elastizit Und Die Bedürfnisse Der Festigkeitslehre
,” Zeitschrift VDI.,
29
, pp. 797–807.
26.
Zheng
,
Y. R.
,
Shen, Z. J.
, and
Gong, X. N.
,
2002
,
The Principles of Geotechnical Plastic Mechanics
,
China Architecture and Building Press
,
Beijing (In Chinese)
.
27.
Fjær
,
E.
,
Holt, R. M.
,
Horsrud, P.
,
Raaen, A. M.
, and
Risnes, R.
,
2008
,
Petroleum Related Rock Mechanics
,
2nd ed.
,
Elsevier
,
Amsterdam, The Netherlands
.
28.
Bohloli
,
B.
, and
Pater
,
C. J.
,
2006
, “
Experimental Study on Hydraulic Fracturing of Soft Rocks: Influence of Fluid Rheology and Confining Stress
,”
J. Pet. Sci. Eng.
,
53
(
1–2
), pp.
1
12
.
29.
Skempton
,
A. W.
,
1954
, “
Pore-Pressure Coefficients A and B
,”
Geotechnique
,
4
(
4
), pp.
143
147
.
30.
Henkel
,
D. J.
,
1959
, “
The Relationship Between the Strength, Pore Water Pressure and Volume Change Characteristics of Saturated Clays
,”
Geotechnique.
,
9
(
3
), pp.
119
135
.
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