Wireless distributed test system based on transient pressure signal detection and recognition

During the test on transient pressure signal in explosion field,false trigger caused by field interference can lead to test failure.To improve the stability of test system,a signal detection and recognition technology is proposed for transient pressure test system.In the process of signal acquisition,firstly,electrical levels are monitored in real time to find effective abrupt changes and mark them;then the effective data segments are detecdted totected;thus the effective signals can be acquired in turn finally.The experimental results show that the shock wave signal can be collected effectively and the reliability of the test system can be improved after removal of interferences.

Harnessing deep transient testing for reservoir characterization and CO_(2) emission reduction in challenging geological settings

This paper provides a comprehensive overview of Deep Transient Testing(DTT),a cutting-edge technique for reservoir characterization that has revolutionized the oil and gas industry.The main aim of DTT is to characterize the reservoir with a deeper radius of investigation.The optimization of the radius of investigation with the DTT approach is studied in detail.Reveal is a commercial numerical simulation application used to simulate the DTT process and evaluate the pressure wave analysis in the porous media.The main aim of the simulation is to understand the impact of the reservoir quality on the pressure response and use it to address the noise-to-pule ratio,which is a determinantal parameter in testing duration.The tested wells with the DTT tool show that measured well productivity can deliver the minimum commercial rate.The has been delivered within 2 days compared to the potential test time of 21 days which saved the 19 rig days and contributed to C02 emission reduction of(gas flaring 1340+rig emission 600)1940 Metric tons equivalent to 421 cars emission in a year.However,DTT also presents certain limitations,such as the requirement for specialized equipment and expertise,as well as the potential for formation damage during testing.This study provides a detailed description of the DTT technique,encompassing its history,theory,and practical applications.Furthermore,it discusses the benefits and limitations of DTT and presents case studies to illustrate its effectiveness across various reservoir types.Overall,this study serves as a valuable resource for reservoir engineers,geologists,and other professionals involved in the exploration and production of oil and gas.

Time-dependent viscoelastic behavior of an LDPE melt

Two differential constitutive equations, i.e. Giesekus model and Johnson-Segalman model were employed here to predict the time-dependent viscoelastic behavior of an LDPE melt in thixotropy-loop experiments and step shear rate experiment. Multiple relaxation modes were adopted, and the parameters used to describe the nonlinear viscoelasticity in the two models were obtained by fitting the shear-thinning viscosity. The predictions on those transient shear characteristics by the two models are found in qualitative agreement with our previous experiments. JohnsonSegalman model predicts oscillation behavior in the thixotropy-loop and step shear rate experiments, whereas Giesekus model does not. Both models predict higher shear stresses than the experimental data in the case of long time shearing, implying that both models are not able to completely characterize the time-dependent shear stress of the melt at high shear rate.

A well test model for stress-sensitive and heterogeneous reservoirs with non-uniform thicknesses

In view of the anisotropy,heterogeneity and stress-sensitive permeability in low permeability reservoirs,an analytical well test model was established by introducing the concept of permeability modulus.This model considered the permeability stress-sensitivity,wellbore storage effect,and the skin effect.The perturbation technique and Laplace transformation were used to solve the mathematical model analytically in Laplace space,and the bottom-hole pressure type curves were plotted and analyzed in real space by using the Stehfest numerical inversion.

Modeling and Analysis for Practical CT Based on Transient Test and Parameter Identification

In the transient process of power grid faults,the transferring distortion of current transformer(CT)can seriously affect relay protection performance.Under these conditions,it is difficult to analyze the ferromagnetic characteristic of the magnetizing branch in the transient equivalent circuit of CT.The Jiles-Atherton hysteresis model(J-A model),which is widely used in digital simulations,can accurately describe the hysteresis and saturation process of the core characteristics;however,to acquire the parameters of the J-A model of current transformers in practical use is still a challenging problem.In this paper,physical tests based on a practical CT and parameter identification are presented to solve the problem.The basic hysteresis loops of P,PR,and TPY class of practical current transformers are obtained through physical tests.Thus,the J-A model parameters are identified using a hybrid genetic/simulated annealing algorithm,based on which transient simulation models of different class CTs are constructed.The effectiveness of the proposed method is verified via dynamic physical simulation tests.A typical accident is analyzed based on these models.

Theory and application of the transient injection well test

Based on the theory of the pumping well test,the transient injection well test was suggested in this paper.The design method and the scope of application are discussed in detail.The mathematical models are developed for the short-time and long-time transient injection test respectively.A double logarithm type curve matching method was introduced for analyzing the field transient injection test data.A set of methods for the transient injection test design,experiment performance and data analysis were established.Some field tests were analyzed,and the results show that the test model and method are suitable for the transient injection test and can be used to deal with the real engineering problems.

Characterizing hydraulic fractures in shale gas reservoirs using transient pressure tests

Hydraulic fracturing combined with horizontal drilling has been the technology that makes it possible to economically produce natural gas from unconventional shale gas or tight gas reservoirs.Hydraulic fracturing operations,in particular,multistage fracturing treatments along with horizontal wells in unconventional formations create complex fracture geometries or networks,which are difficult to characterize.The traditional analysis using a single vertical or horizontal fracture concept may be no longer applicable.Knowledge of these created fracture properties,such as their spatial distribution,extension and fracture areas,is essential information to evaluate stimulation results.However,there are currently few effective approaches available for quantifying hydraulic fractures in unconventional reservoirs.This work presents an unconventional gas reservoir simulator and its application to quantify hydraulic fractures in shale gas reservoirs using transient pressure data.The numerical model incorporates most known physical processes for gas production from unconventional reservoirs,including two-phase flow of liquid and gas,Klinkenberg effect,non-Darcy flow,and nonlinear adsorption.In addition,the model is able to handle various types and scales of fractures or heterogeneity using continuum,discrete or hybrid modeling approaches under different well production conditions of varying rate or pressure.Our modeling studies indicate that the most sensitive parameter of hydraulic fractures to early transient gas flow through extremely low permeability rock is actually the fracture-matrix contacting area,generated by fracturing stimulation.Based on this observation,it is possible to use transient pressure testing data to estimate the area of fractures generated from fracturing operations.We will conduct a series of modeling studies and present a methodology using typical transient pressure responses,simulated by the numerical model,to estimate fracture areas created or to quantity hydraulic fractures with traditional well testing technology.The type curves of pressure transients from this study can be used to quantify hydraulic fractures in field application.

A NUMERICAL PRESSURE TRANSIENT MODEL FOR MULTILAYERED GAS RESERVOIRS WITH PSEUDOSTEADY STATE FORMATION CROSSFLOW

Reservoir deposition occurs over geologic periods of time. Although reservoirs are assumed to be homogenous for simplicity of analysis, most reservoirs are heterogeneous in nature. Some common forms of hetergeneity are the presence of layers and the presence of different zones of fluids and/or rock in the formation. A modified semi-permeable model for multi-layered gas reservoirs with pseudo-steady state interlayer crossflow was developed. The model accounted for the effect of skin and wellbore storage, considers all layers open to a single well, which flows at constant total rate. This new numerical solution was proved to be computationally very efficient, and it has been validated by comparing the results with those of some simple, well known models in the well testing literature. The effects of the reservoir parameters such as permeability, vertical permeability, skin, wellbore storage on the wellbore response, pressure and layer production rate were investigated. Numerical solutions of the problem for the modified semi-permeable model were used to find the structure of crossflow in typical cases.

Wafer-level SLID bonding for MEMS encapsulation

Hermetic packaging is often an essential requirement to enable proper functionality throughout the device＇s lifetime and ensure the optimal performance of a micro electronic mechanical system （MEMS） device. Solid-liquid interdiffusion （SLID） bonding is a novel and attractive way to encapsulate MEMS devices at a wafer level. SLID bonding utilizes a low-melting-point metal to reduce the bonding process temperature; and metallic seal rings take out less of the valuable surface area and have a lower gas permeability compared to polymer or glass- based sealing materials. In addition, ductile metals can adopt mechanical and thermo-mechanical stresses during their service lifetime, which improves their reliability. In this study, the principles of Au-Sn and Cu-Sn SLID bonding are presented, which are meant to be used for wafer-level hermetic sealing of MEMS resonators. Seal rings in 15.24 cm silicon wafers were bonded at a width of 60 gin, electroplated, and used with Au-Sn and Cu-Sn layer structures. The wafer bonding temperature varied between 300 ℃ and 350 ℃, and the bonding force was 3.5 kN under the ambient pressure, that is, it was less than 0.1 Pa. A shear test was used to compare the mechanical properties of the interconnections between both material systems, in addition, important factors pertaining to bond ring design are discussed according to their effects on the failure mechanisms. The results show that the design ofmetal structures can significantly affect the reliability of bond rings.