Polysiloxane, as an organic silicon polymer， can be chemically modified by block copolymerization. Because of its abundant raw materials and excellent properties of modified products, it has been extensively studied by scholars. In this paper, the research progress of polysiloxane block copolymers at home and abroad was reviewed. Some kind of polysiloxane block copolymers modified by polyurea, polyurethane, polyether, polyamide and polyimide were mainly introduced. Also, its performance and application were summarized, and the prospect of its application was forecasted.
The pore structure inside the exfoliated graphite makes it have excellent adsorption performance, especially for the adsorption of oil molecules. Oily wastewater from simulated oilfield plant was prepared with diesel oil and oil extracted from oily sludge. The effects of mass ratio of oil to expanded graphite, adsorption time and pH on oil adsorption by expanded graphite were investigated. The optimum conditions for the adsorption of diesel oil by exfoliated graphite are as follows: the mass ratio of oil to graphite is 50∶7,the stirring time is 10 minutes, without adjusting pH.The optimum conditions for heavy oil adsorption are as follows: the mass ratio of oil to graphite is 50∶8, the stirring time is 10 minutes, without adjusting pH; and the adsorption of expanded graphite to oil conforms to the distribution adsorption law.
The phase change microcapsules with methyl methacrylate as the shell material and 58# paraffin as the core material were prepared by suspension polymerization. The effects of some factors on the properties of the microcapsules were studied, such as the amounts of emulsifiers and initiators, the mass ratios of the core and shell materials. Chemical compositions, surface morphologies, thermal properties and stabilities of the microcapsules were characterized by Fourier transform infrared (FT⁃IR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The results showed that when the mass fractions of emulsifier PVP and initiator AIBN were 7.0% and 3.9%, respectively, the microcapsules had the best morphology. When the mass ratio of the core and shell material was 3∶1, the microcapsule had a regular spherical shape with a smooth surface. At the same time, the microcapsule with the high enthalpy of phase change had a high heat storage property and stability. The quantity of heat involved in phase transition was 126.97 J/g and the content of paraffin wax as the core material was 85.4%.
Through in⁃depth study on the condensing recovery process of shale oil,Aspen plus software was used to simulate the process and optimize the oil shale condensation recovery system.The results show that the yield of shale oil is 80.6% after the simulation of Aspen Plus software.Two schemes are used to optimize the condensation recovery system.In the first scheme,the absorption tower can be removed and the equipment cost can be saved without the need of the saturated gas as the heat carrier. By changing the position of the fan and comparing the oil yield under the full⁃negative pressure and the semi⁃negative pressure.In the second scheme, the yield of shale oil increases by 1% in the semi⁃negative pressure, and the yield of oil increases by nearly 3 million.
Nanocrystalline ZSM⁃5 zeolites were synthesized by hydrothermal synthesis using 30% silica sol as silica source and aluminium sulfate as aluminium source. The obtained samples were characterized by XRD, SEM, BET and NH3⁃TPD characterization methods, and the effects of different pH on the physico⁃chemical properties of nanocrystalline accumulation ZSM⁃5 molecular sieve were investigated. The results showed that when the pH value was 11.50, the catalyst had nano⁃scale structure, large surface area, large number of mesopores and suitable acidity. The application of thiophene alkylation showed better thiophene alkylation activity.
A comparative experimental study on the fracture conductivity between the self propping agent and the “propping agent + carrier fluid” has been carried out, and the mechanism analysis has been carried out. The results show that whether the self supporting proppant or the “propping agent + carrier fluid”, the fracture conductivity decreases with the increasing of closing pressure. With the increase of sand concentration, the conductivity of fracture increases. Compared with those of quartz sand, the compressive strength and the fracture conductivity of ceramsite are obviously higher. On the one hand, the polymer carrying liquids can enhance the compressive strength of proppant, reduce the crushing rate, and further increase the conductivity of fracture. On the other hand, the retention of carrier fluid among proppant particles will result in decrease in permeability, which will reduce the conductivity of fractures. Therefore, the fracture conductivity is the result of the interaction of permeability and fracture rate. Compared with that of the “proppant + carrier fluid”, the breaking rate of the self propping proppant is slightly higher, which has no obvious effect on fracture conductivity. It can be seen that the process of the self suspension proppant has no effect on the proppant compressive strength and the fracture diversion.
Aiming at the problem of insufficient understanding of thin and poor reservoir waterflooding development, 40 phase permeability curves with thin and poor reservoir characteristics are screened out by collecting relevant in⁃situ permeability and reservoir physical properties data, and these permeability data are processed and analyzed by using statistical principle and method. The results show that the permeability curves of thin⁃difference reservoirs are mainly of three types: convex, concave and straight⁃line. According to the permeability distribution range of thin and poor reservoirs, the permeability curves can be divided into four permeability levels: below 10 mD, 10~100 mD, 100~200 mD and above 200 mD. The typical permeability curves of the same permeability level are analyzed, and it is concluded that the permeability characteristics of thin and poor reservoirs generally present the characteristics of "double high and double bottom". By analyzing the permeability curves and their characteristic parameters of thin and poor reservoirs with different permeability grades in different development stages, it is concluded that the permeability curves of different permeability grades will have different changes and effects under long⁃term water injection conditions, on the one hand, the enlarged and beneficial effects of phase permeability, on the other hand, the reduced and adverse effects of phase permeability.
The injection solution of ASP flooding in X12 area reacts with formation minerals to form scales, and then precipitates from the produced fluid and accumulates in the produced wells, which is easy to cause scaling and affect production. Through the analysis of scale sample, the main components of scale are defined, and the scaling regularity is studied. The purpose of cleaning and preventing scale in production wells is realized by using open scale prevention pump, pre⁃scaling process pipe string and dropping dosing measures. The results show that carbonate scale is the main scale component of weak alkali ASP flooding in X12 area, accounting for more than 78% of the scale sample quality; with the ASP injection, the vale of CO〖_(3)^(2-)〗 and pH increase gradually, while changes of Ca〖^(2+)〗+Mg〖^(2+)〗+Ba〖^(2+)〗 show the shape of curve of "rising⁃stabilizing⁃falling"; the scale mainly occurs after the ASP injection of 0.23 PV, and the concentration of CO〖_(3)^(2-)〗exceeds 140 mg/L. From the right shoulder of the⁃type concentration line of Ca〖^(2+)〗+Mg〖^(2+)〗+Ba〖^(2+)〗 above pH 8.3, the descending range of 0~15% is gradually accelerated; a set of underground surface scale prevention measures is formed by putting open scale prevention card pump at the extraction end, adopting pre⁃scaling process pipe string, and installing drip dosing device in the fouling well, with an average period of 167 days prolonged. And a set of underground surface scale⁃proof technical system was formed. The research has certain guiding significance for the development of combined flooding and scaling prevention technology.
The water saturation distribution field can truly reflect the water flooding in the oil well, but the accuracy of water saturation field depends greatly on the application of a single index to evaluate the water flooding level. In this paper, a fuzzy comprehensive evaluation model is proposed, which can effectively identify the water flooded level of well layer, including the parameter system, weight system and index classification criteria. Taking the actual data of each layer of 408 wells in the Xinbei development area as an example, the water flooded classification system is used to judge the water flooded level in each layer. The results show that the water flooded level of the one well network is heavy and the water flooded level of the two and three wells is low, which provides a reliable basis for the remaining oil and water plugging treatment in the next step.
Aiming at the demanding requirements of sealing performance in ultra⁃deep oil and gas wells, a double main sealing structure consisting of conical surface to conical surface and cylindrical surface to spherical surface was designed based on the special thread sealing mechanism. Using numerical simulation method, the changes of contact stress and the contact length of the sealing surface under the four conditions of tensile, compression, tension and internal pressure, tension and internal and external pressures were analyzed. The sealing performance of threaded joints under the ultimate load was studied, and the change rule of sealing capacity with different loads was obtained. The full⁃scale test results show that the sealing performance of the double main seal premium threaded joint meets the application requirements.
New clean fracturing fluid VES⁃YF was prepared by mixing the betain type amphoteric surfactant YF⁃1 and cosurfactant YF⁃2 with KCl. By measuring the influence of different concentration of YF⁃1, YF⁃2 and KCl on the viscosity of fracturing fluid, the optimized formulation was obtained, which is 2.0%YF⁃1+1.0%YF⁃2+2.0%KCl. The research and evaluation of the system's construction mechanism and its applicable performance were conducted. The results show that VES⁃YF clean fracturing fluid has shear thinning property and good viscoelasticity. The rheological measurement shows that the network structure of worm⁃like micelle exists in the system and can be recovered after shear failure. The apparent viscosity of VES⁃YF clean fracturing fluid is still higher than 80 mPa·s after shearing for 2 h at the temperature of 45 ℃ and the shearing rate of 170 s-1. The system has the advantages of strong sand carrying capacity, good gel breaking property and low core damage rate. VES⁃YF clean fracturing fluid has a broad application prospects in the fracturing operation of low permeability reservoir.
In order to study the influence of gravel size and strength characteristics on the propagation mode and mechanical parameters of glutenite, a heterogeneous core model of glutenite was established by using the rock fracture process simulation system RFPA. The failure process and fracture propagation law of sandy conglomerate core and the variation of elastic mechanical parameters such as compressive strength, Young's modulus and Poisson's ratio with the change of gravel size and mechanical properties were studied. The results showed that with the increase of gravel size, core model of Poisson and Young's modulus increase gradually, intensity, and increase with the decrease of the first and core crack morphology of different gravel size is almost the same; With the increase of gravel strength, the compressive strength of rock uniaxial compressive strength gradually increased, and then remained basically unchanged, mainly determined by matrix strength. The results reproduce the process of crack initiation and propagation of gravel, and the influence law of gravel size and strength on core fracture is obtained.
The northern transitional zone of Area S has the characteristics of high water cut, low oil recovery rate, rapid production decline, rapid rise of comprehensive water cut and poor development effect in oilfield development. In order to improve the development effect of the transition zone, the test of steam flooding infill adjustment was carried out in three or four zones in the northern transition zone. In this paper, a fine structure model and a fine reservoir model were established for the test area, historical fitting and precision analysis were made for the geological reserves and production, and set adjustment was made for the test area. Therefore, the change rule of the index before and after well pattern infilling and the effect evaluation can also effectively solve the problem of low reserve utilization caused by poor reservoir development and poor physical property of crude oil in the transitional zone. The research in this paper can also effectively guide the adjustment of measures and the preparation of comprehensive schemes.
Determining reasonable formation pressure plays an important role in improving oil recovery, reducing water consumption and casing loss rate. Whether the formation pressure is reasonable or not is also related to the stable production and economic benefits of the oilfield. For ultra⁃high water cut reservoirs, the study of formation pressure is relatively rare, and the existing methods do not take into account the influence of different viscosity, recovery degree and gas⁃oil ratio on reasonable formation pressure. Therefore, material balance method, gas⁃oil ratio dynamic data analysis method and numerical simulation method, are used to study the variation law of different viscosities, recovery degree, gas⁃oil ratio and formation pressure. Reasonable formation pressure values of each block are calculated, considering the influence of dissolved gas on crude oil viscosity and recovery factor, and the reasonable formation pressure values in the west part of central block of Daqing Oilfield are determined. The results show that the reasonable formation pressure in the west of the central region is close to the saturation pressure, the reasonable formation pressure in Sapu formation is 9.11 MPa, and the reasonable formation pressure in Gaotaizi formation is 10.12 MPa, which has important guiding significance for the later waterflooding development of Daqing Oilfield.
Alluvial fan is a typical continental fan accumulation formed after the outflow of the river (flood). There are two kinds of sedimentary mechanism, the traction flow and the debris flow in the fan root area，which make the sedimentary model of alluvial fan complicated. The exposed alluvial fan phenomenon is well in Zhebu countryside, Laiyang city, Shandong province, which belongs to Cretaceous Wangshi group Xingezhuang Formation. Through the detailed observation and measurement on the section, using the sedimentary principle of the outcrop, the sedimentary environment was thought being an alluvial fan, which developed chaotic accumulation of conglomerate facies (Gms), massive bedding conglomerate facies (Gmh), trough cross bedding sandstone facies (St), planer cross bedding sandstone facies (Sp), horizontal bedding sandstones (Sh), floodplain mudstone (Fl) and massive bedding mudstone (M). The trough flow facies belt, slice flow facies belt, braid flow facies belt, runoff facies belt were identified. The facies of the trough flow belt and the slice flow facies belt were the least exposed, and the upper part of the main section was mostly debris flow deposits. The facies of the runoff facies and the braided flow facies were the most exposed, showing the characteristics of the interaction between sand and mud. In view of this, based on the study of the sedimentary characteristics of different facies zones, the sedimentary model was established and the evolution characteristics of the profile were analyzed combined with the outcrop characteristics of alluvial fan in Laiyang, Shandong province.
After the shutdown of the waxy crude oil pipeline, the wax⁃crystals in the crude oil will gradually separate out when the temperature in the pipe falls below the wax precipitation point. According to the variation of viscoelasticity of waxy crude oil with temperature in temperature drop process, a method for dividing the temperature⁃drop stage during the shutdown of pipeline was put forward by using the relation of the storage modulus, loss modulus and loss angle with temperature. The temperature drop process was divided into three stages with the critical point of wax precipitation point and the temperature point when the storage modulus and loss modulus were equal (loss angle equaled 45 degrees). Taking the Huage pipeline as an example, FLUENT was used to describe the temperature drop process and calculate the solution. In addition, crude oil with different properties was selected to verify the method, and the rule of temperature drop in waxy crude oil pipeline was obtained.
