Accurate prediction of fracture initiation pressure is the key process in hydraulic fracturing and acid fracturing.Penetration effect plays an important role in calculating fracture initiation pressures.But at present，percolation，injection rate and liquid viscosity are seldom considered to the prediction models of initiation pressure in fractured wells.Rock is a porous medium，the fracturing fluid will infiltrate into the zone around the wellbore in fracturing，which can make the pressure distribution around the wellbore change and create additional stress interference on fracture initiation pressures in hydraulic fracturing.A prediction model for fracture initiation pressure of open-hole wellbore is established with taking penetration effect into account and combining the theory of rock mechanics，elasticity and seepage mechanics in this context.The incremental boundary iterative method is used to solve the moving boundary problem.The reliability and rationality of the model are verified by comparing with the fracture initiation pressure test and the classical Hubbert model.The influence of penetration effect on the fracture initiation pressure of an open-hole wellbore is analyzed by using the model and the calculation results show that with the increase of rock permeability，injection rate and borehole size，the fracturing fluid is easier to flow into the formation rock，resulting in the increase of pore fluid pressure and the decrease of fracture pressure obviously；with the compressibility of fracturing fluid and fracturing fluid viscosity increases，the fracturing fluid is not easy to infiltrate，and thus infiltration of fracturing fluid has little effect on the fracture initiation pressure.The model established in this paper overcomes the disadvantages that Hubbert model cannot take the effect of penetration on reservoir fracture pressure into account，and explains the mechanism of penetration effect on reducing reservoir fracture initiation pressure effectively.
Zeng Fan-hui, Tang Bo-tao, Wang Tao, Guo Jian-chun, Xiao Yong-jun, Zhang Shou-ren
. Prediction model of fracture initiation pressure of open hole well considering penetration effect[J]. Natural Gas Geoscience, 2019
, 30(4)
: 549
-556
.
DOI: 10.11764/j.issn.1672-1926.2019.01.010
［1］Chen Mian，Zhou Jian，Jin Yan，et al.Experimental study on fracturing features in naturally fractured reservoir[J].Acta Petrolei Sinica，2008，29(3):431-434.
陈勉，周健，金衍，等.随机裂缝性储层压裂特征实验研究[J].石油学报，2008，29(3):431-434.
[2]Fallahzadeh S H，Rasouli V，Sarmadivaleh M.An investigation of hydraulic fracturing initiation and near-wellbore propagation from perforated boreholes in tight formations[J].Rock Mechanics and Rock Engineering，2015，48(2):573-584.
[3]Schmitt D R，Zoback M D.Poroelastic effects in the determination of the maximum horizontal principal stress in hydraulic fracturing tests：A proposed breakdown equation employing a modified effective stress relation for tensile failure[J].International Journal of Rock Mechanics & Mining Sciences & Geomechanics Abstracts，1989，26(6):499-506.
[4]Li Chuanliang，Kong Xiangyan.A theoretical study on rock breakdown pressure calculation equations of fracturing process[J].Oil Drilling and Production Technology，2000，22(2):54-56.
李传亮，孔详言.油井压裂过程中岩石破裂压力计算公式的理论研究[J].石油钻采工艺，2000，22(2):54-56.
[5]Huang Rongzun.A model for predicting formation initiation pressure[J].Journal of East China Petroleum Institute，1984(4):335-346.
黄荣樽.地层破裂压力预测模式的探讨[J].华东石油学院学报，1984(4):335-346.
[6]He Jianming，Chong Lin.Initiation，propagation，closure and morphology of hydraulic fractures in sandstone cores[J].Fuel，2017，208:65-70.
[7]Liu Xiang.Study on earth stress and fracturing pressure in vertical perforated wells[J].Drilling and Production Technology，2008，31(2):36-38.
刘翔.垂直射孔井地应力及破裂压力研究[J].钻采工艺，2008，31(2):36-38.
[8]Stanchits S，Surdi A，Gathogo P，et al.Onset of hydraulic fracture initiation monitored by acoustic emission and volumetric deformation measurements[J].Rock Mechanics & Rock Engineering，2014，47(5):1521-1532.
[9]Jin Yan，Zhang Xudong，Chen Mian.Initiation pressure models for hydraulic fracturing of vertical wells in naturally fractured formation[J].Acta Petrolei Sinica，2005，26(6):113-114.
金衍，张旭东，陈勉.天然裂缝地层中垂直井水力裂缝起裂压力模型研究[J].石油学报，2005，26(6):113-114.
[10]Yew C H.Mechanics of Hydraulic Fracturing[J].Developments in Petroleum Science，1997，210(7):369-390.
[11]Van Ketterij R C.De Pater.Impact of perforations on hydraulic fracture tortuosity[J].Production & Facilities，1999，14(2):117-130.
[12]Schmitt D R，Zoback M D.Infiltration effects in the tensile rupture of thin walled cylinders of glass and granite:Implications for the hydraulic fracturing breakdown equation[J].International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts，1993(94):289-303.
[13]Haimson B，Fairhurst C.Hydraulic fracturing in porous-permeable materials[J].Journal of Petroleum Technology，1969，21(7):811-817.
[14]Li Y.Improving fracture initiation predictions of a horizontal wellbore in laminated anisotropy shales[J].Journal of Natural Gas Science and Engineering，2015，24:390-399.
[15]Chen Mian，Jin Yan，Zhang Guangqing.Petroleum Engineering Rock Mechanics[M].Beijing:Science Press，2008.
陈勉，金衍，张广清.石油工程岩石力学[M].北京:科学出版社，2008.
[16]Zhu H.Hydraulic fracture initiation and propagation from wellbore with oriented perforation[J].Rock Mechanics and Rock Engineering，2015，48(2):585-601.
[17]Shimizu H，Murata S，Ishida T.The distinct element analysis for hydraulic fracturing with fluid having different viscosity[J].International Journal of Rock Mechanics & Mining Sciences，2011，48(5):712-727.
[18]Carslaw H S.Conduction of heat in solids and heat conduction[J].Physics Today，1948，1(7):24-30.
[19]Biot M A.General theory of three-dimensional consolidation[J].Journal of Applied Physics，2004，12(2):155-164.
[20]King G W.Drilling engineering for subsea development wells[J].Journal of Petroleum Technology，1990，42(9):1176-1183.
[21]Ito T.Effect of pore pressure gradient on fracture initiation in fluid saturated porous media:Rock[J].Engineering Fracture Mechanics，2008，75(7):1753-1762.
[22]Timoshenko S P，Goodier J N.Elasticity Theory[M].3rd Edition.Beijing:Tsinghua University Press，2004:66-67.
[23]Zeng Fanhui，Guo Jianchun，Liu Yuxuan.A finite element model to predict wellbore fracture pessure with Acid Damage[J].Sains Malaysiana，2015，44(10):1377-1388.
[24]Green A E，Lindsay K A.Thermoelasticity[J].Journal of Elasticity，1972，2(1):1-7.
[25]Imberger J，Patterson C.A dynamic reservoir simulation model[J].Transport Models/Inland & Coastal Waters，1981:310-361.
[26]Polubarinova-kochina P Y.Theory of Ground Water Movement[M].Princeton:Princeton University Press，1963:50-55.
[27]Dietz D.Determination of average reservoir pressure from build-up surveys[J].Journal of Petroleum Technology，1965，17(8):955-959.
[28]Yew C H.Mechanics of hydraulic fracturing[J].Developments in Petroleum Science，1997，210(7):369-390.
[29]Garagash D，Detournay E.An analysis of the influence of the pressurization rate on the borehole breakdown pressure[J].International Journal of Solids & Structures，1997，34(24):3099-3118.
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