An adaptive physics-informed deep learning method for pore pressure prediction using seismic data

Accurate prediction of formation pore pressure is essential to predict fluid flow and manage hydrocarbon production in petroleum engineering.Recent deep learning technique has been receiving more interest due to the great potential to deal with pore pressure prediction.However,most of the traditional deep learning models are less efficient to address generalization problems.To fill this technical gap,in this work,we developed a new adaptive physics-informed deep learning model with high generalization capability to predict pore pressure values directly from seismic data.Specifically,the new model,named CGP-NN,consists of a novel parametric features extraction approach(1DCPP),a stacked multilayer gated recurrent model(multilayer GRU),and an adaptive physics-informed loss function.Through machine training,the developed model can automatically select the optimal physical model to constrain the results for each pore pressure prediction.The CGP-NN model has the best generalization when the physicsrelated metricλ=0.5.A hybrid approach combining Eaton and Bowers methods is also proposed to build machine-learnable labels for solving the problem of few labels.To validate the developed model and methodology,a case study on a complex reservoir in Tarim Basin was further performed to demonstrate the high accuracy on the pore pressure prediction of new wells along with the strong generalization ability.The adaptive physics-informed deep learning approach presented here has potential application in the prediction of pore pressures coupled with multiple genesis mechanisms using seismic data.

A continuous and long-term in-situ stress measuring method based on fiber optic. Part I: Theory of inverse differential strain analysis

A method for in-situ stress measurement via fiber optics was proposed. The method utilizes the relationship between rock mass elastic parameters and in-situ stress. The approach offers the advantage of long-term stress measurements with high spatial resolution and frequency, significantly enhancing the ability to measure in-situ stress. The sensing casing, spirally wrapped with fiber optic, is cemented into the formation to establish a formation sensing nerve. Injecting fluid into the casing generates strain disturbance, establishing the relationship between rock mass properties and treatment pressure.Moreover, an optimization algorithm is established to invert the elastic parameters of formation via fiber optic strains. In the first part of this paper series, we established the theoretical basis for the inverse differential strain analysis method for in-situ stress measurement, which was subsequently verified using an analytical model. This paper is the fundamental basis for the inverse differential strain analysis method.

Wellbore Cleaning Degree and Hydraulic Extension in Shale Oil Horizontal Wells

The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.

Understanding hydraulic fracture propagation behavior in tight sandstone–coal interbedded formations: an experimentalinvestigation

Whether hydraulic fractures could connect multiple gas zones in the vertical plane is the key to fracturing treatment to jointly exploit coalbed methane and tight sandstone gas through integrative hydraulic fracturing in tight sandstone–coal interbedded formations. Laboratory true triaxial hydraulic fracturing experiments were conducted on layered specimens with di erent combination types of natural sandstone and coal to simulate the propagation behavior of hydraulic fractures. The effects of the fracture initiation position, fracturing fluid viscosity and injection rate were discussed. The results showed that di erent fracture morphologies could be found. When initiating from coal seams, three patterns of fracture initiation and propagation were obtained:(1) The main hydraulic fracture initiated and propagated along the natural fractures and then diverged due to the effects of in situ stress and formed secondary fractures.(2) The hydraulic fracture initiated and propagated in the direction of the maximum horizontal stress.(3) Multiple fractures initiated and propagated at the same time. With the same fracturing fluid viscosity and injection rate, the hydraulic fractures initiating in sandstones had greater chances than those in coal seams to penetrate interfaces and enter neighboring layers. Excessively small or large fracturing fluid viscosity and injection rate would do harm to the vertical extension height of the induced fracture and improvement of the stimulated reservoir volume. Compared with operation parameters(fracturing fluid viscosity and injection rate), the natural weak planes in coals were considered to be the key factor that a ected the fracture propagation path. The experimental results would make some contributions to the development of tight sandstone–coal interbedded reservoirs.

Clinical significance of dynamic detection for serum levels of MCP-1,TNF-α and IL-8 in patients with acute pancreatitis

Objective:To observe dynamic changes of levels of monocyte chemotactic protein-1(MCP-1),tumor necrosis factor-α(TNF-α) and interleukin-8(IL-8) in patients with acute pancreatitis and to investigate its evaluation value on the severity of acute pancreatitis.Methods:A total of 109 patients with acute pancreatitis admitted were divided into mild acute pancreatitis group(MAP group,42 cases),moderately severe acute pancreatitis(MSAP group,35 cases)and severe acute pancreatitis(SAP group,32 cases).ELISA was used to detect the serum levels of MCP-1,TNF-α and IL-8 of patients at day 1,day 4 and day 7 of admission to hospital.Results:The serum levels of MCP-1,TNF-α and IL-8 from MAP group,MSAP group and SAP group at day 1 of admission to hospital all significantly increased.There was a significant difference between MAP group and control group,MSAP group and MAP group,SAP group and MSAP group(P<0.05).The serum concentrations of IL-8 from MASP group and SAP group obviously increased at day 1,and there was significant difference between MASP group and MAP group,SAP group and MSAP group(P<0.05),while the difference between MAP group and control group was not obvious(P>0.05);The serum concentrations of MCP-1,TNF-α and IL-8 from MAP group all reached the highest level at day 4,which were significantly higher than the detection levels at day 1.In MSAP group and SAP group,the serum concentrations of MCP-1,TNF-α and IL-8 were the highest at day 1,which were significantly higher than the detection levels at day 4 and 7.At each detecting timing,the serum concentrations of MCP-1,TNF-α and IL-8 from MSAP group and SAP group were all higher than those of MAP group and MSAP group,respectively.Conclusions:The dynamic changes of serum levels of MCP-1,TNF-α and IL-8 in patients with acute pancreatitis have their rules,and the change rule of MAP group was different with that of MSAP and SAP group,which showed the reference value for the diagnosis and illness severity evaluation of acute pancreatitis.

Experimental study of multi-timescale crack blunting in hydraulic fracture

Hydraulic fracture is important in unconventional oil and gas exploration.During the propagation of the hydraulic fracture,the crack tip is blunted due to the development of the process zone in the near-tip area.In this study,the blunting of the hydraulic fracture in polymethyl methacrylate specimens due to multi-timescale stress concentration is investigated.The ratio of the initiation toughness to the arrest toughness of the blunted hydraulic fracture is measured using both the dynamic and the static methods.Results show that a hydraulic fracture can be blunted with the time span of stress concentration from 1 ms to 600 s.It is also shown that the blunting of hydraulic fracture is a highly localized process.The morphology of the blunted crack depends on the stress distribution in the vicinity of the crack tip.

Numerical stress analysis for the multi-casing structure inside a wellbore in the formation using the boundary element method

A multi-casing structure in drilling engineering can be considered as an inhomogeneous body consisting of many different materials. The mechanical behavior of the inhomogeneous body in an infinite domain is very com- plicated. In this paper, a detailed expression about the fictitious stress method of the boundary element method （BEM） is demonstrated for the inhomogeneous body. Then the fictitious stress method is deployed to investigate the stresses for the multi-casing structure under non-uniform loading conditions and an irregular wellbore. Three examples of the multi-casing structure in the borehole imply the high effectiveness of BEM for complex geometries related to the borehole in an infinite formation. The effects of casing eccentricity and the interfacial gap on the stress field are discussed. The eccentric casing takes the potential yield when the eccentric orientation is along the direction of Sh. Under different eccentric orientations, the yon Mises stress in the casing increases with increasing degree of eccentricity. The radial stress in the multi-casing structure is always continuous along the radius, but the circumferential stress is discontinuous at the interface. The radial stress decreases and the circumferential stress increases with the increasing of the interfacial gap between the adjacent materials.

An in situ dressing material containing a multi-armed antibiotic for healing irregular wounds

Acute and infected wounds resulting from accidents,battlefield trauma,or surgical interventions have become a global healthcare burden due to the complex bacterial infection environment.However,conventional gauze dressings present insufficient contact with irregular wounds and lack antibacterial activity against multi-drug-resistant bacteria.In this study,we develop in situ nanofibrous dressings tailored tofit wounds of various shapes and sizes while providing nanoscale comfort and excellent antibacterial properties.Our approach involves the fabrication of these dressings using a handheld electrospinning device that allows for the direct depo-sition of nanofiber dressings onto specific irregular wound sites,resulting in perfect conformal wound closure without any mismatch in 2 min.The nanofibrous dressings are loaded with multi-armed antibiotics that exhibit outstanding antibacterial activ-ity against Staphylococcus aureus(S.aureus)and methicillin-resistant S.aureus.Compared to conventional vancomycin,this in situ nanofibrous dressing shows great antibacterial performance against up to 98%of multi-drug-resistant bacteria.In vitro and in vivo experiments demonstrate the ability of in situ nanofibrous dressings to prevent multi-drug-resistant bacterial infection,greatly alleviate inflammation,and promote wound healing.Ourfindings highlight the potential of these personalized nanofibrous dressings for clinical applications,including emergency,accident,and surgical healthcare treatment.

3D-printed,citrate-based bioresorbable vascular scaffolds for coronary artery angioplasty

Fully bioresorbable vascular scaffolds(BVSs)aim to overcome the limitations of metallic drug-eluting stents(DESs).However,polymer-based BVSs,such as Abbott’s Absorb,the only US FDA-approved BVS,have had limited use due to increased strut thickness(157μm for Absorb),exacerbated tissue inflammation,and increased risk of major cardiac events leading to inferior clinical performance when compared to metallic DESs.Herein we report the development of a drug-eluting BVS(DE-BVS)through the innovative use of a photopolymerizable,citrate-based biomaterial and a high-precision additive manufacturing process.BVS with a clinically relevant strut thickness of 62μm can be produced in a high-throughput manner,i.e.one BVS per minute,and controlled release of the anti-restenosis drug everolimus can be achieved by engineering the structure of polymer coatings to fabricate drug-eluting BVS.We achieved the successful deployment of BVSs and DE-BVSs in swine coronary arteries using a custom-built balloon catheter and BVS delivery system and confirmed BVS safety and efficacy regarding maintenance of vessel patency for 28 days,observing an inflammation profile for BVS and DE-BVS that was comparable to the commercial XIENCE^(TM)DES(Abbott Vascular).

Antibacterial ability and biocompatibility of fluorinated titanium by plasma-based surface modification

Biomaterial surfaces with satisfied antibacterial activity and appropriate cytocompatibility are a pressing clinical need for orthopedic and dental implants.Fluorinecontaining biomaterials have been demonstrated to obtain antibacterial activity and osteogenic property,while the effect of fluorine chemical compositions on antibacterial property and cytocompatibility is rarely studied.To this end,the coatings with different fluorine chemical compositions on titanium surface were prepared by plasma treatment to verify the antibacterial ability and cytocompatibility of fluorinated surfaces.Their antibacterial ability was evaluated by using Staphylococcus aureus,and the cell compatibility was investigated with MC3T3-E1 cells in vitro.The results show that both fluorocarbon coating and metal fluorides coating exhibited a hydrophilic and nano-scaled roughness.Rather than the fluorocarbon coating,the coating composed of metal fluorides presented satisfied bactericide effect and excellent cytocompatibility.The antibacterial mechanism is associated with the metal fluorides and released fluoride ion.This work would provide novel sight in optimizing the surface modification method of fluorinated biomaterials for biomedical applications.

Antibacterial property and bioadaptability of Ti6Al4V alloy with a silvered gradient nanostructured surface layer

In this paper,a silvered gradient nanostructured(GNS)layer was successfully fabricated on Ti6Al4V surface by means of surface ultrasonic rolling treatment(SURT)combined with silvering process.Surface characteristics,mechanical properties,corrosion resistance,antibacterial ability and cytotoxicity of GNS Ag/Ti6Al4V were investigated in comparison with those of coarse-grained(CG)and GNS Ti6Al4V samples.Owing to the greatly enhanced diffusion kinetics of Ag in the GNS layer,surface silvering on GNS Ti6Al4V was achieved at a relatively low temperature(500℃),and the release rate of Ag^(+)was substantially accelerated,which endowed GNS Ag/Ti6Al4V with excellent antibacterial property.Moreover,improved wear and corrosion resistance of GNS Ag/Ti6Al4V can be achieved without cytotoxicity,indicating excellent bioadaptability.