Hasil untuk "Petroleum refining. Petroleum products"

Alexandre Lavrov

Abstract Carter’s equation is routinely used to describe the leak-off rate and the cumulative fluid loss during deposition of solids on porous media from a suspension. According to this equation, the leak-off rate is inversely proportional to the square root of time. This creates an unphysical singularity at time equal to zero. To remove this singularity, a modification is made to Carter’s law in this contribution. Another modification to Carter’s law made herein accounts for dynamic loss conditions where cross-flow filtration leads to only partial deposition. The modified leak-off law provides a satisfactory fit to the experimental data as long as cross flow is not turbulent. The modified leak-off law is calibrated against experimental data of an earlier study, in both static and dynamic fluid loss tests. A static fluid loss test is used to calibrate the model for the filter cake porosity and permeability as well as spurt loss. Dynamic fluid loss tests are then used to calibrate the model for the particle adhesion probability for each shear rate value.

Ping Enshun, Wang Yuzhong, Ren Baoliang et al.

The wellhead device is prone to washout in the process of slug sand fracturing or blowing while production， which makes it impossible to address the risk of well control in time， thus imposing a serious potential safety hazard. An innovative automatic-setting wellhead plug and supporting hydraulic fishing tool were developed. In this paper， the main structures， working principles， main technical performance parameters and features of the device and tool were introduced， and the laboratory performance evaluation test was performed on the physical prototype of the automatic-setting wellhead plug. The test results show that under the 15 MPa wellbore pressure， the stop pin of the automatic-setting wellhead plug is pulled to allow the plug to fall into the wellbore freely， so as to realize automatic release and delay automatic setting， and meet the requirement of sealing at 50 MPa. The hydraulic fishing tool can be used to pressurize 10 MPa to realize automatic unsealing and pressure relief for equilibrium before the wellhead plug is safely lifted. The developed plug and tool are ready for field testing， and they have been proved effective for addressing the problem of wellhead washout in a short time. Thus， the plug and tool are prospective for popularization and application.

ZHANG CHAO, ZHU PENGYU, HUANG TIANJING et al.

Most oilfields currently using CO₂ flooding in China have transitioned from water flooding to CO₂ injection for development. Over prolonged periods, CO₂-water-rock reactions can alter reservoir physical properties, becoming a key issue that must be addressed. To address limitations in existing studies—such as short reaction durations and unclear effects of environmental variables—this research used a high-temperature, high-pressure reactor to simulate reservoir conditions. Advanced equipment, including high-performance field-emission scanning electron microscope and X-ray diffraction, was utilized to study the effects and mechanisms of CO₂-water-rock reactions on reservoir physical properties and mineral compositions under different environmental variables. The experimental results indicated that feldspar dissolution and clay mineral formation were the primary factors affecting reservoir physical properties after CO₂-water-rock reactions. With increasing temperature, the water-rock reaction intensified, accelerating the dissolution of potassium feldspar, calcium feldspar, and sodium feldspar while increasing the proportion of kaolinite, thereby improving reservoir physical properties. When pressure increased, the dissolution of large amounts of CO₂ lowered the solution pH and inhibited the transformation of minerals such as potassium feldspar and sodium feldspar into clay minerals like kaolinite, causing deterioration in overall reservoir physical properties. As the reaction time increased, the dissolution of feldspar and carbonate minerals intensified, leading to increased mass concentrations of major ions such as Na⁺, K⁺, Ca²⁺, an improvement in reservoir physical properties, and the precipitation of gypsum. Within the experimental range, the degree of mineral dissolution caused by CO₂-water-rock reactions exhibited a positive correlation with temperature and time but a negative correlation with injection pressure. Finally, the experimental results were calculated using the Kozeny-Carman equation, indicating that within the experimental range, reservoir porosity and permeability are positively correlated with temperature and time, and negatively correlated with CO₂ injection pressure. By studying the impact of CO₂-water-rock reactions on reservoirs under different environmental variables, this study offers insights for the application of CO₂ flooding to enhance oil recovery (EOR) in shale oil reservoirs.

Liu Penglin, Li Jun, Xi Yan et al.

Fault slip in multi-stage fracturing of shale gas is the main factor leading to the shear deformation of casing in shale gas horizontal wells,which seriously affects the productivity of shale gas horizontal wells.However,there is no effective method to calculate the fault slip at present.Accordingly,the stress state of the fault in the multi-stage fracturing process of shale gas horizontal wells was analyzed in this paper.A fault slip model and calculation method were established considering the influence of upper and lower strata on the fault.The change rule of the fault slip under the influence of different factors was studied by using finite element software.The results show that,in the process of fault slip,the slip from the top to the bottom of the fault decreases gradually due to the elasticity of the stratum,showing an inverted S shape.Factors such as the decrease of friction coefficient of fault plane,the decrease of elastic modulus of fault rock,the increase of elastic modulus of rock in the lower strata of the fault and the increase of horizontal minimum in-situ stress all increase the fault slip.While Poisson's ratio of fault rock,Poisson's ratio of rock in the lower strata and vertical in-situ stress have small influences on the fault slip.The research results provide a reference for the fracturing parameter control of shale gas horizontal wells.

Zhang Ruiyao, Li Jun, Liu Gonghui et al.

In order to solve the problem of low separation efficiency of separator in hollow sphere injected dual-gradient drilling, the dynamic variation of wellbore pressure was studied. A filter separator capable of efficiently separating hollow spheres was designed and verified by numerical simulation and laboratory test, and the highest separation efficiency can reach 98.5%. The mathematical model of fluctuating pressure generated by the separation of hollow sphere into the annulus was built; combined with the model and considering the dynamic variation of the volume fraction of hollow sphere, the drilling fluid displacement, the separator position and the rate of penetration, the mathematical model of dynamic variation of wellbore pressure was further built. Based on drilling data, case calculation and influential factor analysis were carried out. The research results show that the wellbore pressure distribution has an obvious inflection point at the position of the separator, while the distribution of drilling fluid density in the annulus has an abrupt change; by means of dynamically adjusting the key parameters such as the volume fraction of the hollow sphere and the position of the separator, the density of unweighted drilling fluid in the annulus, the length of the liquid column and the bottom pressure while drilling can be flexibly adjusted, and thus realize the real-time prediction of the bottomhole pressure while drilling. The research results provide theoretical basis and technical support for safe drilling under narrow pressure window conditions.

李胜忠, 张铜鋆, 聂军 et al.

To solve the problem of inaccuracy of MWD instruments caused by downhole high-temperature environment,ZLZY310 high-temperature drilling fluid cooling system was developed.Based on the heat exchange theory,the influence of the drilling fluid entry temperature on the temperature of downhole drilling fluid was analyzed and the temperature change of the drilling fluid when it is still was considered,the technical parameters of the cooling system were determined.With plate heat exchanger,the heat exchange efficiency of drilling fluid cooling system is over 85%.The heat-exchanged water is dissipated by several sets of cooling towers,which work based on the principle of air cooling and evaporation.The backwashing process of drilling fluid was designed,which can solve the problem of pipe plugging by impurities in drilling fluid.The drilling fluid cooling system has been applied in the oil field,and the processing capacity of drilling fluid reaches up to 150～260 m³/h,which has obvious cooling effect compared with similar cooling devices.The circulating cooling capacity of drilling fluid meets the requirements of field operation and reduces the influence of formation temperature on downhole tools.The research results provide effective technical support for drilling fluid cooling and backwashing processes during drilling.

Wei YAN, Bing LUO, Gang ZHOU et al.

Based on drilling data of JT1 and CS1, outcrop profiles and seismic data, the sedimentary pattern, space configuration of source-reservoir-cap combinations and paleouplift evolution characteristics of the Cambrian Lower Canglangpu Member in the central Sichuan paleouplift have been investigated to determine the favorable exploration zones. Controlled by Deyang-Anyue rift, the Lower Canglangpu Member features differential characteristics from east to west in sedimentary framework. In the west side of the Deyang-Anyue rift, this member is composed of clastic sediments, while in the east side of the Deyang-Anyue rift, it is fresh water shelf sediments, with grain beaches occurring along edges of the depressions, shelf and lagoon. Among the beaches, the dolomitic ones are mainly distributed around the depression edge and in the north of the lagoon. The beach sediments could become high quality reservoirs under the effect of karstification. Underlying the Lower Canglangpu Member is the widespread source rock of the Qiongzhusi Formation, so oil and gas generated by the Qiongzhusi Formation source rock can directly charge into the beach reservoirs. The sandy mudstone of the Upper Canglangpu Member can serve as the caprock of the Lower Canglangpu Member reservoir. The dolomitic beaches are located at the higher part of the paleo-uplift during the main accumulation period, with good hydrocarbon accumulation elements. Blocks PT1-CS1, HT1-GT2 and east GT2 are favorable exploration zones.

陈智, 张友军, 朱峰 et al.

The underground coal gasification (UCG) technology is basically mature, but the influence of its own process and tools slows down its industrialization progress. This paper introduced the development and field test of two new UCG coiled-tubing gasification agent injection tools. The test results show that these two kinds of UCG gasification agent injection tools ensure the injection point under control by conducting downhole temperature measurement and surface monitoring jointly. The problem that the tool is burnt by the backfire is solved by designing a backfire prevention device. To realize low pressure drop, the gasification agent flow channel inside the tool is designed optimally to keep the tool pressure drop not higher than 0.5 MPa and the system pressure drop not higher than 3 MPa. The tool overall has the parameter and functional characteristics of low pressure drop, high temperature resistance, backfire prevention and anti burning to satisfy the demand of field test. This technology is a new domestic achievement in the development of UCG technology and equipment. The research conclusions can provide the technical reference for developing a new generation of UCG technology.

Rong Xin, Zhu Hongwu, Chu Bingchuan

The solid particles in the offshore oil and gas production will cause erosive wear of the subsea Christmas tree, which will reduce its pressure bearing capacity. For this reason, the micro-erosion mechanism and law of AISI 8630, a commonly used material of subsea Christmas tree, is studied. Through scanning electron microscopy to photograph the surface microcosmic appearance and gas-solid erosion test, the erosion model of AISI 8630 material is obtained, and is analyzed and compared with the erosion model and test data of DNV, E/CRC and Oka. The research results show that when the impact angle is lower than 15°, the erosion rate increases with the impact angle. When the impact angle is between 15° and 30°, the erosion rate is the most serious. when it is larger than 30°, the erosion rate decreases with the impact angle. As the impact velocity increases, the erosion rate increases exponentially. When the particle size is less than 200 μm, the erosion rate increases with the particle size. When the particle size is larger than 200 μm, the erosion rate remains basically s

Wang Gang, Li Wanjun, Liu Feng et al.

The North Tluwa Oilfield and Zhanazhol Oilfield are located on the eastern edge of Pre-Caspian Basin in Kazakhstan, where complex carbonate oil and gas reservoirs present many problems like complex geological structure, large boundary and thickness change of target layer, serious reservoir pressure depletion, low reservoir drilling rate and low mechanical drilling speed in deep abrasive limestone. In order to address the above problems, by the casing program optimization, fit-in-purpose drill bit, rotary geosteering tool and drilling fluid system selection, the key technologies for drilling and completion of horizontal wells with long lateral section in the area have been established. The technologies were first tested in Well H814 in the North Tluwa. As of December 2017, 8 wells have been applied with the average increased drilling rate about 45% and the average increased reservoir drilling rate of 41.95%, proving the feasibility of the technologies in the region. In view of the strong stratigraphic regularity of Pre-Caspian Basin, the established key technologies for horizontal well drilling could provide guidance and references for enhancing drilling speed and improving reservoir drilling rate.

Shaine Mohammadali Lalji, Javed Haneef, Muhammad Arqam Khan et al.

Abstract Drilling in Barents Sea proves to be a challenging task, as this region is situated in auroral zones having high geomagnetic latitude, where magnetic interferences develop from magnetic field and magnetic materials inside subsurface are quite common. For this region, monitoring of magnetic field is utterly significant as any fluctuations can distort the tool sensor performance with ultimately enlarging the uncertainty in azimuth. To guide a well to its desire location, measurement while drilling (MWD) tool needs to be operated with utmost precision; however, its accuracy compromises as a result of magnetic interferences from drill string and nearby magnetic material. The performance of this tool depends upon its sensors. Any distortion in sensor performance can lead to problems such as multiple sidetracking and increase in overall project cost. Furthermore, the same BHA was also placed in a region of Pakistan and the impact drill string interference was observed. It was discovered that the interferences that had tremendous impact on magnetometer Z-component in Barents Sea had a drastic reduction in the region of Pakistan as it is situated in low latitude, where uncertainty in azimuth is low. In this work, an exemplary bottom-hole assembly (BHA) was analyzed and the impact of individual drill string components interferences was observed on the MWD sensors. It was perceived that the bit was responsible for creating the major distortion in MWD sensor. Apart from that, it was also investigated that the location of the well also plays a vital role in this distortion. This intervention in the sensors is created by a vast difference between the used actual length and the recommended length of nonmagnetic drill collar in the BHA. Numerically, it was investigated that if the physical distance between the sensors and bit is increased, then this interference is reduced. It was also apparent that the Z-component of the magnetometer was utterly distorted because of this interference, while the X- and Y-components were proved to be independent of these interferences. It was further examined that the effects of latitude and longitude play a significant role in the course of changing the impact of these errors on magnetization.

Wang Meng, Wang Haizhu, Li Gensheng et al.

Supercritical CO₂ (SC-CO₂) fracturing is one of the new waterless fracturing technologies, which has been drawn much attention because of its environmental friendly and highly efficient advantages. However, the capacity and behavior of proppant transport with SC-CO₂ in fracture have not been figured out yet owing to lower density and viscosity of SC-CO₂. The two-phase flow model of SC-CO₂ and proppant in fracture during SC-CO₂ fracturing was established using computational fluid dynamic method (CFD) considering the particle interaction and the property of SC-CO₂. The effects of proppant density, particle size, sand ratio and displacement were analyzed. The research results indicate that the proppant volume fraction has obvious differences in the vertical profile of fracture. With the injection time increasing, the proppant volume fraction of static granular layer generally remains stable. The proppant volume fraction in contact layer and suspension layer vary gently, but changes dramatically in saltation layer. Under the simulated conditions, proppant density of less than 1 540 kg/m³, proppant size of smaller than 0.25 mm, sand ratio of lower than 8% and injection rate of higher than 4 kg/s are proposed to form uniform proppant bed and avoid sand blocking. The study is expected to provide a theoretical basis for the design of proppant transport with SC-CO₂ in fracture.

Chen Anming, Chen Zhenliang, Shi Huaizhong et al.

Coiled tubing modulation locally underbalanced drilling can effectively control the near bit annular pressure at the bottom of the well, and ensure the stability of the borehole above the packer at the same time as the near bit underbalanced drilling is realized. In order to study the underbalance situation of the drilling technology and the law of cyclic pressure loss, the experimental system and device of the continuous tube modulation partial underbalanced drilling were designed and developed, and the pressure distribution and the microspace debris migration test were preliminarily carried out. The analysis results show that the continuous tube modulated local underbalanced drilling test device is mainly composed of test frame, reflux device, rotating sealed rock drainage device and so on. It can simulate the local underbalanced drilling process of continuous tube modulation, and the test system can carry on the change law of the pressure difference near the bit near the bottom of the well, the law of the near bit drilling fluid carrying rock and the micro drilling fluid. Study on the law of carrying rock in annular drilling fluid. The conclusions can provide reference for the field application of continuous pipe modulated partial underbalanced drilling technology.

Hasan N. Al-SAEDI, Ralph E. FLORI

Sandstone core and free-clay sandstone core were prepared in chromatography columns, and core flooding experiments were performed to determine the EOR mechanisms of low salinity (LS) water flooding and analyze the effect of clay on recovery factor. First, brine with a high salinity (HS) of 100 000 mg/L was injected to simulate formation water. Then, LS water of 1 000 mg/L was then injected at different temperatures. Concentrations of Ca2+ and CH3COO− and pH of the fluid flowing out of the chromatography column were recorded. The results showed that during flooding the free-clay core with LS water, the carboxylic acid detached from the sand, as great as that of the clay-containing cores. It showed a noteworthy desorption of Ca2+ from the free-clay core surface, which indicated that LS water flooding resulted in a high recovery in sandstone without clay. Compared with HS water flooding, in the LS water flooding, the pH of produced fluid increased significantly; also, as the temperature increased, the pH and Ca2+ concentration of the produced fluid decreased; and the hydrophilic property of the sandstone was stronger. The results of oil recovery tests using the same columns were in line with the chemical analyses. The oil recovery from the free-clay columns was as great as from the column clay-containing column. The results of wettability measurements supported our theory. Key words: sandstone reservoir, low salinity water flooding, enhanced oil recovery, water-rock reaction, wettability alteration, clay

Liu Gang, Li Yichen, Wang Kai et al.

To address the sanding monitor issue in wells during high water cut period, wavelet packet analysis method is used to identify sand vibration signals at the pipe wall. A sanding monitoring laboratory test was designed to obtain sand vibration signal, which is decomposed by db4 wavelet packet and three layers. The energy of each component is normalized. The signal component containing the sanding characteristics is analyzed and reconstructed. The high frequency band fine decomposition method is used to highlight the frequency domain localization characteristics of the sanding signal. The frequency domain feature of the reconstructed signal indicates that the sanding signal frequency range is 19~25 kHz. The power spectrum characteristics of the reconstructed signal indicate that the power spectrum amplitude of the sanding signal has a quadratic increase relationship with the sand content. The wavelet packet analysis method can effectively identify the sanding vibration signal. The conclusions provide a reference for identifying the sanding information of wells under complex fluid conditions.

Eman Shakir, Zahraa Zahraw, Abdul Hameed M.J. Al-Obaidy

The present study focuses on the environmental and health risks associated with the use of treated wastewater produced from Al-Rustamia third extension plant for irrigation. The measured data are used to evaluate comprehensive pollution index (CPI) and organic pollution index (OPI). The average CPI was found as 0.69 which indicated to be slightly polluted for all seasons and a similar result was also obtained with OPI, which is found to slightly vary in the range 1.29–1.60 which indicates as being to be contaminated. Also to evaluate its suitability for irrigation purposes, Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP) and Residual Sodium Carbonate (RSC) were calculated following standard equations and found experimentally as (8.70), (74.76) and (2.68) respectively. Irrigation water classes are used for Salinity hazard (EC) and Sodium hazard (SAR) to assess water suitability for irrigation, and it is found that samples in summer and autumn in the class of C3-S1, indicate high salinity and low sodium water, while in spring and winter in the class of C4-S1, they indicate very high-salinity. Furthermore, the data indicate a slight to moderate degree of restriction on the use of this treated wastewater in irrigation due to chloride hazard. RSC value is more than 1.25 at all seasons, indicating that samples in summer and autumn are doubtful for irrigation purposes, while the samples in spring and winter are unsuitable for irrigation.

Xiao Wensheng, Sun Ruqi, Yue Aili et al.

The periodic excitation of the offshore skid-mounted fracturing equipment is prone to cause damage to its bottom support during the operation on offshore platform or deck.To address the issue,dynamic simulation analysis on the main excitation source of skid-mounted fracturing equipment-five-cylinder reciprocating piston pump has been conducted.The analysis showed that the largest exciting force generated in the second gear,so that the second gear was set as an analysis example.The dynamic simulation analysis of skid-mounted fracturing equipment under different connection schemes has been conducted by using ADAMS.The results showed that the exciting force is smaller and stable when the skid-mounted fracturing equipment was supported by eight elastic supports.The results of dynamic response of eight elastic supports is put into ANSYS as the deck’s dynamic responses,the results showed that the deck’s dynamic responses could meet the merchant deck vibrating comprehensive evaluation criteria.The vibration system for offshore skid-mounted fracturing equipment could provide a certain reference value.

叶茂, 段梦兰, 徐崇崴 et al.

A.M. Al-Sabagh, H.M. Abd-El-Bary, R.A. El-Ghazawy et al.

Linear alkyl benzene sulfonic acid (L) and three of its ester derivatives (L1, L2, L3) were prepared, followed by quaternization of these esters (L1Q, L2Q, L3Q). The corrosion inhibition effect on carbon steel in 1 M HCl was studied using weight loss and potentiodynamic polarization measurements. The adsorption of the inhibitors on carbon steel surface obeyed the Langmuir’s adsorption isotherm. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy (ΔH∗), entropy (ΔS∗) of activation, adsorption–desorption equilibrium constant (Kads), standard free energy of adsorption (ΔGoads), heat (ΔHoads), and entropy of adsorption (ΔSoads) were calculated to elaborate the corrosion inhibition mechanism.