A Pioneer in Technology Research Pursuing His Dream in the Oilfield

Wu Chunsheng is a senior engineer of oil and gas field development,and the deputy director of the Oil Production Technology Research Institute of the No.10 Oil Production Plant of PetroChina Changqing Oilfield Company.He has devoted himself to working in the field of oilfield development technology since the very beginning of his career.During the period of"Building a Western Daqing Oilfield"and the"Second Round of Development Acceleration"in Changqing Oilfield,he worked hard and studied diligently,and took the initiative to take on responsibilities while focused on practical work,growing into an outstanding young technical cadre step by step.His achievements in the research,application,promotion of new techniques and technologies,and the application of scientific research results proved extraordinary.

Enhanced oil recovery mechanisms of polymer flooding in a heterogeneous oil reservoir

Taking reservoir rocks and fluids of the Daqing,Dagang and Changqing oilfields as research objects,the EOR mechanisms and technical approach of polymer flooding were discussed.By comparing the displacement performances of ordinary polymer,glycerol,polymer in"sheet-net"structure and heterogeneous weak gel at the same viscosity and concentration,the relationship between the viscosity of polymer displacement agents and displacement performance was demonstrated,and the method of improving polymer flooding effect was worked out.The main mechanism of polymer flooding to increase oil recovery is the swept volume expansion of water injection due to polymer retention in porous media.The viscosity of polymer agents has no positive correlation with polymer flooding effect.Although polymer of"sheet-net"structure has strong capacity in increasing viscosity,it has poor compatibility with pore throat structure of reservoir rock,low injectivity and low shear resistance.Heterogeneous weak gel system has higher adsorption and capture capacity in porous media,which is easy to retain in porous media,and can effectively establish seepage resistance in high permeability layers(zones).Compared with polymer solutions with the same viscosity or concentration,it has stronger ability to expand swept volume.Long term injection of polymer flooding agents will inevitably lead to fluid entry profile reversal,and thus worsening of polymer flooding effect.Alternate injection of high retention and low or non-retention displacement agents can further improve the displacement effect of polymer flooding agents.

Porothermoelastic response of an oil sand formation subjected to injection and micro-fracturing in horizontal wells

Stimulation of unconsolidated formations via horizontal wells has seen its vast implementation in the recent development of heavy oil reservoir to save the time and cost of preheating the reservoir before the steam-assisted gravity drainage(SAGD)process.A mathematical approach was proposed in this research that fully couples the hydraulic,mechanical and thermal responses of unconsolidated sandstone formations and also applies failure criteria for describing either shear dilation or tensile parting mechanism that generates microcracks.The approach was implemented to predict the porothermoelastic response of a pair of SAGD wells subject to injection and subsequent micro-fracturing using hot water.It was found that the predicted bottom hole pressures(BHPs)match closely with the field observed data.An elliptical dilation zone developed around the dual wells with relatively high pore pressure,porosity,permeability and temperature,implying good interwell hydraulic communication between both wells.The activation of microcracks dramatically accelerated the dissipation of pore pressure across the entire formation depth and also facilitated heat convection in between the dual wells,though to a lesser extent.In summary,the approach provides a convenient means to assist field engineers in the optimization of injection efficiency and evaluation of interference among multiple horizontal wells.

New method for plugging channeling in oil field by nitrogen foam

In order to present a new method for plugging channeling in oil field,the injection modes and validity period of foam system which plugged the formation water layer were studied by means of the experimental model which simulated the real conditions of oil wells existing channeling.Above all,the influence factors including reservoir pressure,permeability,oil saturation and gas-to-liquid ratio were studied through dynamic experiment.Then,in light of the technology characteristics of foam injection in oil field,the comparison between gas-liquid and liquid-gas injection modes was studied.The result shows that the gas-liquid injection mode can ensure the foam injectivity and plugging performance.The plugging validity of nitrogen foam injected into the formation water layer was evaluated in different plugging pressure gradients by the dynamic method which is more reasonable than the static evaluation method in laboratory.The research demonstrates that the plugging validity period of foam decreases with plugging pressure gradient increasing.If the plugging pressure gradient is 0.15 MPa/m,the validity period is 160 h.Finally,a empirical equation and a plate about the plugging validity and the plugging pressure gradient were obtained for forecasting the validity period of foam.

巨厚砂砾岩储层X形水力裂缝的形成——以中国渤海湾盆地储层为例

中国渤海湾盆地致密砂砾岩储层广泛发育,它们通常为深埋巨厚储层,其有效开发需依赖水力压裂技术。为了研究砂砾岩储层水力裂缝的扩展特征,首先,探究了此地砂砾岩储层的地质条件,包括地层纵向分布规律和岩性特征;然后,通过地面微地震系统对该地区盐222区块几口井的压裂过程进行了监测。结果表明,目标井大多数地层压裂后均形成了X形水力裂缝。本文将储层形成X形水力裂缝的主要原因归于(1)储层非均质性和(2)两条近距离同向扩展的水力裂缝的应力阴影效应,并通过数值模拟等方法对其进行了详细分析和验证。本文的研究成果和结论可为巨厚砂砾岩储层水力裂缝扩展特征的深入研究提供参考依据。

An Extracellular Oligopeptide Permease May Be a Potential Virulence Factor of Vibrio harveyi

An oligopeptide permease A(OppA)was purified from the extracellular product of Vibrio harveyi SF-1.The molecular weight of the purified protein was estimated to be 58 kDa on SDS-PAGE.The purified protein showed phospholipase C activity at the optimal values of temperature 50℃ and pH 8.0.The enzymatic activity decreased when the temperature increased to 40℃.The N-terminal sequence of the purified protein was determined as ADVPAGTKLA,which is similar to that of OppA.The OppA pre-cursor gene was cloned from the genome of V.harveyi SF-1.The gene consisted of 1665 base pairs and encoded a 554 amino acid polypeptide,which showed a high similarity to those of the OppAs of V.harveyi and other Vibrio species.The gene was subcloned into pET-28a(+)and expressed in Escherichia coli.The expressed recombinant protein was purified by Ni-NTA metal affinity chro-matography.The expressed recombinant protein showed a 58 kDa band on SDS-PAGE and exhibited phospholipase C activity with the optima of temperature 50℃ and pH 8.0.The purified protein was toxic to the flounder gill cells.An OppA mutant of V.harveyi SF-1 was constructed by homologous recombination.The mutant strain was less virulent when it was intraperitoneally inoculated to zebra fish,with the LD50 of 5.46×105 CFU fish-1,compared to 3.11×104 CFU fish-1 of the wild-type strain,which indicated that the OppA might play an important role in the pathogenicity of V.harveyi.

Optimal Design of Improved L-shaped Coprime Array Based on Difference and Sum Co-array

The concept of difference and sum co-array(DSCA)has become a new design idea for planar sparse arrays.Inspired by the shifting invariance property of DSCA,a specific configuration named here as the improved L-shaped array is proposed.Compared to other traditional 2D sparse array configurations such as 2D nested arrays and hourglass arrays,the proposed configuration has larger central consecutive ranges in its DSCA,thus increasing the DOF.At the same time,the mutual coupling effect is also reduced due to the enlarged spacing between the adjacent sensors.Simulations further demonstrate the superiority of the proposed arrays in terms of detection performance and estimation accuracy.

Online monitoring of gas-solid two-phase flow using projected CG method in ECT image reconstruction

Electrical capacitance tomography(ECT)is a promising technique for multi-phase flow measurement due to its high speed,low cost and non-intrusive sensing.Image reconstruction for ECT is an inverse problem of finding the permittivity distribution of an object by measuring the electrical capacitances between sets of electrodes placed around its periphery.The conjugate gradient(CG)method is a popular image reconstruction method for ECT,in spite of its low convergence rate.In this paper,an advanced version of the CG method,the projected CG method,is used for image reconstruction of an ECT system.The solution space is projected into the Krylov subspace and the inverse problem is solved by the CG method in a low-dimensional specific subspace.Both static and dynamic experiments were carried out for gas-solid two-phase flows.The flow regimes are identified using the reconstructed images obtained with the projected CG method.The results obtained indicate that the projected CG method improves the quality of reconstructed images and dramatically reduces computation time,as compared to the traditional sensitivity,Landweber,and CG methods.Furthermore,the projected CG method was also used to estimate the important parameters of the pneumatic conveying process,such as the volume concentration,flow velocity and mass flow rate of the solid phase.Therefore,the projected CG method is considered suitable for online gas-solid two-phase flow measurement.

On the localised corrosion of carbon steel induced by the in-situ local damage of porous corrosion products

The effect of in-situ local damage of uniform porous corrosion products on the localised corrosion of carbon steel is investigated using the wire beam electrode technique(WBE)combined with morphology characterisation and electrochemical tests.The WBE measurements demonstrate that the localised corrosion is enhanced by the in-situ local removal of porous corrosion products,supported by the morphology characterisation and electrochemical tests.The enhanced localised corrosion does not originate from the damaged wire in WBE where the corrosion products are removed but from the other undamaged wires,which is reported for the first time.A mechanism is proposed that the intensive anodic polarisation effect of the damaged wire on the undamaged wires could account for the enhanced localised corrosion,which is due to the protective corrosion products newly formed on the damaged surface and the increase in the potential of damaged wire.