ISRM 2023 - PUBLICATIONS

T14: Petroleum engineering and carbon sequestrationLichun JIA, Hu DENG, Dianchen LIU, Zhilin LI, Weicheng LIDrilling & Production Technology Research Institute, CNPC Chuanqing Drilling Engineering Company Limited, People's Republic of ChinaAnalysis of fracture initiation pressure of horizontal well in transversely isotropic shale reservoirsThis study aims at analyzing the fracture initiation pressure (FIP) of horizontal wellbore in anisotropic shale by considering elastic and strength anisotropy. The FIP is deduced as a function of the anisotropic elastic properties, in-situ stresses, anisotropic tensile strength as well as bedding dip. The results show that the increase of the anisotropy of Young’s modulus, Poisson′s ratio and horizontal in-situ stress induces a reduction of the FIP. While an increase of tensile strength ratio Tv/Th and bedding dip will increase the FIP. It is concluded that the influence of Eh/Ev on FIP is the highest, followed by σH/σh, and then Tv/Th, while the influence of Poisson's ratio is the lowest. For the effect of azimuth of horizontal well, the FIP increases first and then decreases when the horizontal borehole azimuth is far away from the direction of maximum horizontal stress. | shale, transversely isotropic, fracture initiation pressure, modulus anisotropy, Poisson′s ratio anisotropy, tensile strength anisotropy
T14: Petroleum engineering and carbon sequestrationLichun JIA, Dengyun LU, Gui TANG, Changhong ZHOUDrilling & Production Technology Research Institute, CNPC Chuanqing Drilling Engineering Company Limited, People's Republic of ChinaAnalysis of time-dependent wellbore instability with a porochemothermoelastic coupling model in tight gas reservoirsMaintaining wellbore stability is a significant task during drilling. This study investigates time-dependent wellbore stability of a tight gas reservoir in central Sichuan Basin of China with a porochemothermoelastic model. The results show that breakout regions gradually enlarge and equivalent collapse pressure increases with exposure time. The breakout enlarge drastically in the first 5d and following a slowly enlargement from 5d to 10d and 30d. And the equivalent collapse pressure is higher than the mud density 1.45g/cm3 at inclination 46° to 80° for t=0d and at inclination 33° to 90° for exposure time 5d, 10d and 30d. Consequently, the mud density 1.65 g/cm3 of borehole inclination above 33° is recommended to stabilize the borehole. | porochemothermoelastic, wellbore stability, tight gas reservoirs, time-dependent
T14: Petroleum engineering and carbon sequestrationNazir MAFAKHERI BASHMAGH (1), Weiren LIN (1), Abbas KHAKSAR MANSHAD (2)1: Kyoto University, Japan; 2: Petroleum University of Technology, IranDetermining the Magnitudes of Maximum and Minimum Horizontal Stresses from Borehole Data: Comparison Between Borehole Failure Approach and Poroelastic Strain ModelThis paper compares the magnitudes of horizontal stresses estimated by the poroelastic horizontal strain model and borehole breakout approaches in one of the oil wells near the Zagros suture zone. First, the poroelastic horizontal strain model was utilized for determining the magnitude of maximum horizontal stresses, using vertical stress, pore pressure, and physical properties of the rock determined based on wireline logs. Then, the breakout approach was employed to determine the magnitude of horizontal stresses. The R2 of the linear regression between the two methods for minimum and maximum horizontal stress was 0.74 and 0.71, respectively. Even though there are different correlations in some depths, the consistency is generally significant, and stress regimes in both methods were consistent in almost all intervals. The results show this method's capability to calibrate the poroelastic strain method using the breakout approach continuously. | Rock failure, In situ stress, poroelastic strain model, Borehole compressive failure
T14: Petroleum engineering and carbon sequestrationShouding LI (1,2,3), Zhiquan YU (4), Supeng ZHANG (1,2,3), Jianming HE (1,2,3), Zhaobin ZHANG (1,2,3), Xiao LI (1,2,3)1: Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China; 2: College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China; 3: Innovation Academy for Earth Science, Chinese Academy of Sciences, Beijing, China; 4: Inspur Group Co Ltd, Jinan, ChinaMechanical anisotropy and tension-shear characteristics of shale in Pengshui area, ChongqingAs an unconventional energy, shale gas is being developed widely. As one of the core means of development for shale gas, hydraulic fracturing is greatly affected by the mechanical properties of shale, especially its anisotropy and shear characteristics related to the activation of natural structural planes. In this paper, the law of anisotropy characterized by wave velocity and its ratio of shale is summarized through the analysis for the velocity of P-wave and S-wave, the strength characteristics of shale under tension-shear condition is also obtained through the mechanical tests on shale samples in different directions. | Shale, mechanical characteristics, anisotropy, tension-shear
T14: Petroleum engineering and carbon sequestrationPengwei ZHANG, Huantong LIU, Lili LI, Baoguo LIUBeijing Jiaotong University, Beijing, ChinaFaults reactivation risk evaluation during water injection into shale gas reservoirs: A case studyHydraulic fracturing is an effective technique for shale gas development, which breaks tight shale by injecting a large amount of fracturing fluid under high pressure. The potential impacts of hydraulic fracturing on the surrounding environments (such as hydraulic fracturing induced earthquakes) have aroused extensive attentions. Hence it is necessary to study on the evolution rules of reservoir in-situ stress and fault stability during the water injection process of hydraulic fracturing. In this work, a three-dimensional geomechanical model of a shale gas reservoir which located in Southwestern China is established firstly; Based on the in-situ stress field, numerical simulations on the influence of local in-situ stress and fault stability during quasi-dynamic and dynamic water injection are made. With the calculated shear strain distribution, a workflow for evaluating the seismic moment response in the fault region during water injection is proposed. | shale gas, geomechanics, pore pressure, in-situ stress field, fault stability
T14: Petroleum engineering and carbon sequestrationGuodong CHENG (1), Xueyu PANG (1), Zhengsong QIU (1), Jiankun QIN (1), Ning LI (2)1: School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, People's Republic of China; 2: Oil and Gas Engineering Research Institute (Tarim oilfield Company), China National Petroleum Corporation, Tarim, People's Republic of ChinaWell Cement Composition Optimization for Deep Well ApplicationsRecent studies had revealed that traditional high-temperature resistant silica-enriched well cements are not suitable for deep well cementing applications due to strength retrogression problems in the long term. This study investigated the use of new admixtures, including fly ash and ground blast furnace slag (GBFS), to mitigate such strength retrogression issue of cement. The combined use of GBFS and silica at optimized dosages effectively prevented well cement strength retrogression up to 30d, but strength reduction and permeability increase were still observed from 30d to 90d. On the other hand, the combined use of fly ash and silica effectively prevented both strength reduction and permeability increase of the well cement. However, the addition of fly ash increased the consistency of cement slurry significantly, making it difficult to pump. Finally, the slurries prepared with mixtures of well cement, silica flour, fly ash, and GBFS exhibited both excellent flowability and long-term strength stability. | Fly ash; Granulated Blast Furnace Slag; Silica-enriched well cement; long-term strength retrogression; ultra-high temperature
T14: Petroleum engineering and carbon sequestrationAly ABDELAZIZ, Phyllis S. WU, Mei LI, Earl MAGSIPOC, Karl PETERSON, Giovanni GRASSELLIDepartment of Civil and Mineral Engineering, University of Toronto, CanadaUnderstanding shale fracture network complexity in the laboratoryHydraulic fracturing is a complex multi-physics process that involves coupling of fluid flow and rock deformation/fracturing. Particularly, the propagation of fluid-driven fractures is a competing process greatly influenced by rock fabric and in-situ stress. However, it remains unclear how rock fabric affects the failure mechanisms and contributes to the resulting fracture network. To understand this, an 80 mm Montney shale outcrop cube was hydraulically fractured in the laboratory under in-situ true triaxial stress conditions. The fractured sample was then digitally 3D reconstructed by merging high-resolution, high-contrast serial section images. In-depth observation of the digitally-reconstructed induced fracture-network revealed the formation of bedding-controlled horizontal fractures, opening against σ2 instead of the theoretically expected σ3. This suggests the key role played by the bedding planes in determining the trajectory of the fluid-driven fracture network. En-echelon fractures observed near the injection borehole are convincing evidence of possible shear failures associated with hydraulic fracturing. | hydraulic fracturing, 3D imaging, serial section reconstruction, true triaxial testing, breakdown pressure, shut-in pressure
T14: Petroleum engineering and carbon sequestrationYuhao LIU (1), Fengshou ZHANG (1), Dingwei WENG (2), Hongbo LIANG (2), Chunming HE (2)1: Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai, China; 2: Research Institute of Petroleum Exploration & Development, PetroChina, Beijing, ChinaNumerical investigations on THM coupled process during water flooding with multiple well patterns under non-isothermal two phase flowA three-dimensional numerical model of non-isothermal two-phase flow in the deformable porous medium during water flooding is described in this paper. Based on the thermal-hydro-mechanical (THM) coupling theory, governing equations of oil-water two-phase flow are integrated additionally and implemented into the open-source finite element framework OpenGeoSys. Temperature-dependent fluid viscosity and fluid density, along with strain-dependent reservoir permeability are also considered. With different well patterns, stress and pore pressure distribution, heat transfer and the flow of injected water in the reservoir during ten years of injection are simulated. According to the numerical results, high temperature can promote fluid flow to improve the treatment performance. Cold water injection causes the normal stress reduction by introducing significant thermal stress. Spatial variation of stress, pore pressure and injected water saturation are affected by different well pattern scenarios. This finding has important consequences in the field operation of water flooding under the environment of large reservoir depth and high temperature. | Water flooding, THM coupling, Two phase flow, Multiple well patterns, OpenGeoSys
T14: Petroleum engineering and carbon sequestrationZhao FENG (1), Fengshou ZHANG (1), Xianda SHEN (2), Bichen YAN (3), Zhaowei CHEN (4)1: Department of Geotechnical Engineering, Tongji University, Shanghai, China; 2: Department of Civil and Environmental Engineering, Clarkson Univeristy, Potsdam, NY, USA; 3: Ali I. Al-Naimi Petroleum Engineering Research Center, Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia; 4: CNPC Drilling Research Institute, Beijing, ChinaA data-driven model for the prediction of stimulated reservoir volume (SRV) evolution during hydraulic fracturingAccurate forecasting of stimulated reservoir volume (SRV) constitutes a key step in field evaluation and optimization during hydraulic fracturing. In this work, a data-driven model is developed to take advantage of field monitored microseismicity and fracturing parameters for predicting SRV ahead of time. A voxelized method is applied to calculate SRV values using recorded microseismicity data. Fracturing parameters along with SRV history are fed into a Long Short-Term Memory (LSTM) network as inputs. This model can successfully characterize the evolution of SRV. The LSTM network has excellent prediction accuracy (R2 > 0.80) at most stages while performing poorly at the initial stages. The influence of SRV history, time lag size and time window length is investigated to confirm the effectiveness of the proposed method. This study provides a new approach for unconventional reservoir hydraulic fracturing assessment using data-driven methods. | Stimulated reservoir volume, Hydraulic fracturing, Data-driven model, Long short-term memory network
T14: Petroleum engineering and carbon sequestrationPankaj RAWAT, Narendra Kumar SAMADHIYAIndian Institute of Technology Roorkee, IndiaLaboratory hydraulic fracturing experiments on thermally treated tight sandstone samples under step up incremental loadingThis paper aims to investigate the effect of thermal treatment on tight sandstone samples during the hydraulic fracturing process. The sandstone samples were preheated at different temperatures and cooled at the same rate (1 ᵒC / min). Step-up incremental loading opted for all hydraulic fracturing experiments. SEM investigations were done on thin sections of fractured samples to find the fractal dimension and tortuosity. After 300 ᵒC, the samples hydro fractured at higher temperatures and showed lower fractal dimensions than those at lower temperatures. The effect of the heat treatment was also observed in the breakdown pressures as they reduced with the increased temperature. Due to the thermal effects, it was also found that the crack tortuosity increased with an increase in temperature. After 300 ᵒC, the degree of micro cracks and the complexity of the fracture growth network increases. | Step up incremental loading, fractal dimension, tortuosity, SEM (Scanning electron microscope) images
T14: Petroleum engineering and carbon sequestrationCecilia LASKOWSKI (1,2), Diego MANZANAL (2), Mauro MUÑIZ-MENÉNDEZ (3), Sandra ORLANDI (1), José ALLARD (1)1: Universidad Nacional de la Patagonia San Juan Bosco, Comodoro Rivadavia, Argentina; 2: Universidad Politécnica de Madrid, Madrid, Spain; 3: Laboratorio de Geotecnia, CEDEX, Madrid, SpainCarbon dioxide impact on the mechanical properties of a sandstone from San Jorge Gulf Basin (Argentina)During the last few years, there has been an increase in awareness related to global warming. In this context, carbon capture and storage comes into play, intending to reduce the emission of greenhouse gases. This research focuses on reservoir rocks from the San Jorge Gulf Basin (Argentina). To analyze the feasibility of storing CO2 in the reservoir layer, this research studies the evolution of the rock’s porosity and mechanical properties, using samples obtained from outcrop. With this aim, a series of tests such as Mercury Intrusion Porosimetry, X-Ray Fluorescence, and Uniaxial Compressive tests were performed over both unaltered and CO2-altered specimens. Preliminary results show a variable affectation of the porosity, mainly in the carbon dioxide contact zone. Carbonated samples also seem to present modifications in their mechanical properties. | carbon dioxide, CO2 geological storage, sandstone, mechanical characterization
T14: Petroleum engineering and carbon sequestrationChenwang GU (1), Yongcun FENG (1), Nan CHEN (2), Xiaorong LI (1), Jingen DENG (1)1: China University of Petroleum Beijing, Beijing, China; 2: Pengbo Operating Company of CNOOC (China) Co., Ltd, Tianjin, ChinaNumerical investigation of cement sheath integrity under thermo-mechanical coupling based on damage mechanicsThe transient changes of pressure and temperature in the wellbore during fracturing could cause cement sheath damage and micro-annulus. In this work, a plastic damage model that considers both damage and yielding is used to describe the full stress-strain mechanical properties of the actual cement sheath. A novel numerical model was established to evaluate the cement sheath integrity considering thermo-mechanical coupling. This model is validated by the laboratory experiment and shows high accuracy. The results indicate that tensile damage occurs inside the cement sheath during the fracturing process, and the maximum damage occurs in the direction of the maximum horizontal stress. The micro-annulus rapidly appears at the first cement sheath interface during depressurization process after injection, which can reach 39.57 μm. With the increase of shutdown time, the micro-annulus gradually decreases. This work reveals the cement sheath failure mechanism and provides a basis for wellbore integrity control. | Cement sheath, Thermo-mechanical coupling, Plastic damage, Micro-annulus
T14: Petroleum engineering and carbon sequestrationYong SHENG (1), Bing BAI (2), Jinzhi ZHU (1), Zexv ZHANG (2), Haiying LU (1), Mian CHEN (2), Yunhu LU (2)1: Tarim Oil Field Company, Petro China; 2: State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing)Mechanism of wellbore collapse for Carboniferous, Ordovician and Cambrian strata in Southwestern Tarim of ChinaSamples corresponding to severe wellbore collapse in Carboniferous, Ordovician and Cambrian strata were collected from oil field company according to drilling and logging data. In this study, X-ray diffraction, hydration inhibition (linear swelling, dispersion and cation exchange capacity) tests and SEM experiments were conducted on representative samples. With the combination of caving analysis, the mechanisms of wellbore collapse were investigated for specific strata in Southwestern Tarim. The results showed that in Carboniferous strata, wellbore collapse was the comprehensive results of mudstone hydration and the existence of weak planes. In Ordovician strata, it could be concluded that the existed natural fractures providing drilling fluid flow path was the dominant factor inducing the wellbore instability. In Cambrian strata, the results showed the salt dissolution was the main reason of borehole collapse. | Hydration inhibition, Microstructure, Caving analysis, Wellbore stability, Southwestern Tarim
T14: Petroleum engineering and carbon sequestrationYiqi ZOU, Xuyue CHEN, Deli GAO, Siyuan YIN, Qiqi YANGChina University of Petroleum, Beijing, ChinaThe challenge of ocean shallow extended reach wells: how to achieve a farther extension limitDue to the shallow vertical depth, offshore shallow extended reach wells usually have a high horizontal displacement to vertical depth ratio. The high friction of drill pipe during drilling limits the extension capacity of the extended reach well. Based on the three-dimensional string mechanical model, this paper analyzes the extension limit under the drilling condition and maximum running depth of 9-5/8 ″ casing under casing running conditions, and concludes that the friction coefficient, wellbore trajectory and drilling equipment are the main parameters limiting the extension limit. The operation parameters and suggestions under different working conditions are given.This research is expected to increase the extension limit of shallow extended reach wells and promote the economic and efficient development of shallow oil and gas. | extended reach well, extension limit, shallow water, downhole string
T14: Petroleum engineering and carbon sequestrationHuiwen PANG (1), Hanqing WANG (2), Yan JIN (1)1: China University of Petroleum-Beijing; 2: Petroleum Exploration and Production Research Institute, SINOPEC, People's Republic of ChinaPrediction of Safe Mud Window Based on Seismic Data in Carbonate FormationTo address the problem of predicting the safe mud window in China's TH oil field, we present a feasible seismic-based workflow that employs machine learning. Initially, multiple drilling fluid and mud loss engineering records were used to establish secure mud density windows for eight distinct wells with differing depths. Then, the well logs served as the link between drilling fluid density and through-well seismic data, and the relationship between drilling fluid density and seismic data was constructed using machine learning techniques involving ensemble learning. Finally, a 3D distribution model of safe drilling fluid density is generated, and its dependability is evaluated. The results of one validation well indicate that the model's complete blind test accuracy exceeds 75%. The model has a transverse resolution of 25 meters and a longitudinal resolution of 15 meters. It may offer theoretical guidance for devising drilling fluid density and wellbore construction. | Safe mud window, Seismic data, Machine learning, Carbonate formation