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Journal of Petroleum Science & Engineering
Elsevier Science B.V.
Journal of Petroleum Science & Engineering

Elsevier Science B.V.

0920-4105

Journal of Petroleum Science & Engineering/Journal Journal of Petroleum Science & Engineering
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    Research on sand control effect and micro-plugging mechanism of sand control medium in the development of natural gas hydrate reservoir

    Jiping DingYuanfang ChengChuanliang Yan
    14页
    查看更多>>摘要：As a kind of potential new clean energy, natural gas hydrates (NGHs) have become a new hotspot in exploration and development. However, the sand production problem in the exploitation of NGH reservoirs seriously restricts the commercial exploitation of NGHs, so the research on sand control in hydrate exploitation is particularly important. In this study, an actual NGH reservoir in the South China Sea was experimentally simulated and sand control experiments were carried out on four different types of sand control elements. Furthermore, the factors, such as pressure, temperature, permeability, the amount of sand production and structure of reservoir skeleton in experiments were analyzed and plugging mechanisms of sand control elements were studied from the microscopic perspective. It is found that the sand production is mainly concentrated in the early stage of the experiment. Moreover, the failure of the reservoir skeleton is shown as non-uniform extension around, and the reservoir skeleton near both sides of the well wall is more seriously damaged than that to the inward. In the sand control experiment, the higher accuracy of sand control elements is, the smaller cumulative sand production, and the morphology of the reservoir skeleton is basically maintained. The experiment shows that the sand control medium is mainly plugged in the radial (Particle agglomeration-induced plugging) and axial (Fine particle invasion-induced plugging) directions, and particle agglomeration-induced plugging and fine particle invasion-induced plugging jointly act on the sand control medium. A water film and fluid flow on the surface of the sand control medium can accelerate particle agglomeration. Sand control elements made of hydrophobic materials can reduce the degree of plugging of the sand control medium. The research results are conducive to understanding mechanisms of sand control elements plugged by gravel during the exploitation of hydrate reservoirs and provide reference for future sand control design.
      原文链接:
    • NSTL

    Light-weight temporary-sealing cement for medium temperature geothermal wells by using polyvinyl alcohol fibers and fly ash cenospheres

    Huijing TanLan ShenYue Zuo
    14页
    查看更多>>摘要：A new lightweight temporary-sealing cement (LTC) is developed in this study to prevent lost circulation and simultaneously protect target formation during drilling. Water-soluble polyvinyl alcohol (PVA) fibers and fly ash cenospheres (FACs), were added to class G cement to develop the LTC for 90-150 °C geothermal wells, on the basis of the temperature change process related to cement plugging. Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS) and total organic carbon (TOC) tests were conducted to investigate the chemical composition, crystalline phases, pore diameter distribution, permeability, microstructure of the specimens and the dissolution rate of PVA fibers in hardened cement. The following conclusions can be drawn. 1) The addition of 10% FACs and 3% PVA fibers optimized the cement slurry density to 1.54 g/cm~3 2) The addition of PVA fibers enhanced the cement flexural strength. And all the compressive strengths of the samples were greater than 6.5 MPa 3) The fibers in hardened cement could maintain integrity in 60 °C water, and remain soluble under 120 °C dry condition, demonstrating that they could work with cement and FACs to seal the fracture for drilling at lower temperature, and dissolve out from hardened cement in ≥90 °C water. 4) Most of the PVA fibers dissolved and leached out of the cement within 4 h in 90 °C water immersion. The elongated holes formed by fiber dissolution, interconnected with other pores in cement matrix, contributing to the less tortuosity and substantially increased permeability of LTC. In general, the enough strength and high permeability of degraded LTC prove that the 90 °C water-soluble PVA fibers and FACs could be used to prepare the partially degradable LTC for 90-150 °C geothermal wells.
      原文链接:
    • NSTL

    Acoustic stimulation of oil production by a downhole emitter based on a jet-driven Helmholtz oscillator

    E.A. MarfinR.N. GataullinA.A. Abdrashitov
    8页
    查看更多>>摘要：Development of oil fields by the most common waterflooding method leads to an increase in the water cut of the recoverable oil and a low oil recovery factor (for Russia, about 30-40%). The solution to this actual problem seems to be in the combination of the applied waterflooding method with the elastic wave action. This paper presents the results of the use of acoustic stimulation as an unconventional but promising approach to enhanced oil recovery. This study developed a borehole emitter and acoustic action technology to stimulate oil production. In this borehole hydrodynamic emitter, based on the jet-driven Helmholtz oscillator, the generation of intense acoustic pressure oscillations occurs due to the energy of the fluid flow injected into the formation. Bench tests made it possible to determine the operating parameters and frequency characteristics of the device. Field tests were carried out in Russia at an oil field that is in a late stage of development. An increase in oil production has been achieved; the water cut of the produced oil has been reduced; the injectivity of the injection well has been increased due to the restoration of the filtration properties of the bottom-hole zone. Thus, the developed technical devices, operating at kilohertz frequencies, and the production technology can be used as a promising method for stimulating oil flow and enhancing oil recovery. The advantages of the proposed acoustic treatment are their relatively low cost, simplicity of device design, high efficiency, and environmental friendliness, as well as the possibility of combining this technology with almost all traditional methods of enhanced oil recovery.
      原文链接:
    • NSTL

    Model-based life cycle control of ICVs in injectors in a benchmark analogous to a pre-salt field

    Vinicius E. BotechiaDenis J. Schiozer
    10页
    查看更多>>摘要：Some fields in the Brazilian pre-salt feature light oil and high gas/CO2 content, which is a bottleneck to oil production due to gas processing restrictions in the facilities. To deal with this, Water-alternate-gas (WAG) is used as a recovery mechanism while the use of Interval Control Valves (ICVs) is also recommended, since these enable controlling the production or injection through segments in the wells. In this context of high gas production and WAG, a good injection management is crucial and the use of ICVs in the injection wells can help to improve the oil production and the field's economic return. In this work, we propose and compare four approaches (A, B, C, and D) to control the ICVs of the injectors considering numerical simulation and Net present value (NPV) as objective function. Approaches A and B use streamlines to correlate producers and injectors, and they also use the Gas-oil ratio (GOR) of the producers as a monitoring variable to close the valves of the injectors. The difference between them is that, in Approach A, the valves remain closed during the entire field's life cycle, while there is an alternation of each opened or closed valve for every WAG cycle in Approach B. In Approach C, the alternation between each valve is made since the beginning of the WAG cycles, instead of waiting for a trigger to start closing the valves. These three approaches are sub-divided into other (minor) approaches, depending on whether the valve remains closed, or not, during the water injection cycles. Finally, in Approach D, we attempt to control the cumulative fluid injection between the zones of the injectors. The study is applied to the SEC1_2022 benchmark case, a synthetic model analogous to a pre-salt field. Finally, we apply the best approach found to a reference case ('true response') to assess how the proposed strategy would behave in real cases. The results indicate that closing the valves in earlier stages of the field's life cycle is better than using GOR as a trigger. Furthermore, the alternation between opened and closed valves proved to be the best way to control the valves in this case. Approach D was the best among those evaluated, with the highest increase in oil production and greatest decrease in water production, providing highest NPV. Although the platform remained constrained by gas production, this approach provided a better fluid distribution in the field and among wells, improving both oil recovery and economic returns.
      原文链接:
    • NSTL

    A new two-dimensional transient forecast model of wellbore temperature based on precise time step integration method

    Liangliang DingChuanjun HanWenkang Chen
    12页
    查看更多>>摘要：Dramatic temperature changes in the wellbore can lead to the severe deformation and breakage of the wellbore string, packer seal malfunction, and other operational accidents. A new two-dimensional (2D) transient forecast model of the wellbore temperature is established to provide accurate temperature parameters for the precision mechanical analysis of the wellbore string and the safety evaluation of well integrity. Furthermore, a precise time step integration scheme of the forecast model using the precise time step integration method of a one-point subdomain is proposed. A solution method for the 2D transient forecast model of the wellbore temperature is proposed by combining the precise time step integration method. Finally, a case study focused on a high-temperature deep gas well with a transient wellbore temperature is presented by comparing the calculation results of the different models and solution methods. The sensitivity analysis of the wellbore temperature is performed as well. The results indicate that the forecast model in this paper has higher accuracy than the existing two-dimensional transient model. By contrast analysis of the finite difference method and the solution method that combines the precise time step integration method, the solution method has the advantages of better convergence and faster calculation speed. The major sensitive parameters that affect the stability time of wellbore temperature are ranked as follows: gas production rate, tubing size, specific heat, temperature gradient, gas relative density, and thermal conductivity. The work presented can provide a theoretical foundation and technological basis for the transient forecast of the wellbore temperature, which is critical for well completion design and wellbore safety evaluation.
      原文链接:
    • NSTL

    Toward investigating the application of reservoir opportunity index in facilitating well placement optimization under geological uncertainty

    Reza YousefzadehMohammad AhmadiAlireza Kazemi
    14页
    查看更多>>摘要：There have been several attempts to reduce the computational costs associated with well placement optimization under geological uncertainty by selecting a representative subset of realizations or by reducing the number of function evaluations to speed up the optimization. Although previous researchers have studied this issue, they have used static or dynamic properties of the reservoir to select a reduced subset of realizations or shrank the search space of the optimizer to reduce the computational burden of the task. Using static parameters is fast but lacks the accuracy of the dynamic approach. On the other hand, dynamic parameters require a computationally expensive full flow simulation. In this paper, a workflow based on the Reservoir Opportunity Index (ROI) maps was proposed to address the two issues mentioned above. The ROI maps were constructed using both the static and dynamic reservoir properties. The dynamic feature was obtained by the computationally efficient Fast Marching Method instead of full reservoir simulation. In this workflow, ROI density (DROI) maps were constructed by averaging the ROI values of adjacent cells to incorporate the effect of neighboring cells in finding potential regions to constrain the search space of the optimizer. In addition, these DROI maps were used to select a representative subset of realizations. Furthermore, the effect of re-selection of the representative realizations was investigated in this study. The proposed workflow was applied to optimize the location of production wells under geological uncertainty and was compared with the Full Case (using all realizations in optimization) in terms of three criteria, namely the expected value, the standard deviation, and the cumulative distribution function (CDF) of the objective function. Results of optimization showed that the constrained search with a fixed number of realizations and the statistical clustering technique outperformed other approaches with minimum differences of 1.5% and 8.9% from the objective function and its standard deviation of the values obtained from the Full Case, respectively. Also, it had 28.64% less difference between its CDF and the Full Case in comparison to the second-best technique. In addition, it was shown that the constrained search required fewer function evaluations to achieve similar results as the global search with approximately three times fewer function evaluations. The results of this paper can be used as a guidance for reservoir engineers to select a proper approach for optimization (constrained or unconstrained), clustering the geological realizations (statistical or K-means), and proper implementation of ROI maps for shrinking the search space of the optimizer and selecting a representative subset of realizations.
      原文链接:
    • NSTL

    New mathematical formulations for accurate estimate of nitrogen leakage rate using distributed temperature sensing in Mechanical Integrity Tests

    Eslam M. SolimanDickson LeeJohn C. Stormont
    15页
    查看更多>>摘要：Current practices for estimating calculated nitrogen leakage rate (CNLR) have been a great challenge in Mechanical Integrity tests (MIT) for underground solution-mined storage caverns due to the insufficient wellbore temperature measurements. The use of a traditional temperature logging system for detecting gas leakage relies on the existence of steady-state temperature conditions which is difficult to validate with current measurement technologies. Accurate estimation of CNLR is essential for making correct decisions on the use of underground caverns. Recently, an advanced MIT system with a new measurement technique, namely distributed temperature sensing (DTS), was developed to overcome the limitations of the conventional measurement system. DTS produces continuous measurements of real-time temperature data throughout the wellbore which are used to estimate the gas leakage rate. In this paper, new mathematical formulations for the DTS system are developed to adapt the new measurement technique and allow incorporating real-time temperature measurements in estimating both volume- and mass-based CNLR. The new mathematical formulations are applicable for unsteady-state temperature conditions and account for the compressibility effect of nitrogen gas. To evaluate the efficiency of the new mathematical formulations, a computational fluid dynamics (CFD) model for a solution-mined wellbore was developed and validated. The CFD model was then used to predict the thermodynamics response of complex leakage scenarios with minimum detectable leak rates (MDLR) for nitrogen and brine. The results demonstrate the ability of the DTS method utilizing the new formulations to improve the accuracy in estimating MDLR compared with conventional temperature logging methods. The advantage of using a mass-based formulation versus volume-based formulation is also highlighted.
      原文链接:
    • NSTL

    A censorious appraisal of the oil well acidizing corrosion inhibitors

    Ifeanyi E. UzomaJoseph A.O. OlugbuyiroMoses M. Solomon
    15页
    查看更多>>摘要：Well acidizing is a common stimulation technique for maximizing the output of oil reservoirs. It helps to overcome the low permeability of wellbore by creating new flow channels or enlarging old ones. Corrosion challenge is encountered during the process since tubings are metallic. Corrosion inhibitors are the defence mechanism used in mitigating corrosion problem during acidizing. This review has identified and grouped acidizing corrosion inhibitors into organic-, and polymer-based. The performance of these inhibitors at temperatures of ≥60 °C and acid concentration of ≥15 wt% is considered. It is noted that greater percentage of studies revolve round the 60 °C. Above 100 °C, the number of scientific articles decreased considerably. Four classes of intensifiers for acidizing corrosion inhibitors have been identified: formic acid, potassium iodide, copper iodide, and antimony chloride. Their chemistries have been discussed. The research gaps identified include (i) scanty information on acidizing inhibitors at temperatures ≥150 °C, (ii) limited information on natural polymers and plant biomaterials as acidizing inhibitors, (iii) scanty information on the mechanism of inhibition at temperatures ≥150 °C, and (v) limited information on the composition of corrosion products under acidizing conditions. Thus, recommendations for future researches have been given.
      原文链接:
    • NSTL

    A review of synthetic polymers as filtration control additives for water-based drilling fluids for high-temperature applications

    Dileep Kumar BalagaSandeep D. Kulkarni
    10页
    查看更多>>摘要：Fluid loss is a well-known problem while drilling oil and gas wells. Minimizing the fluid loss and forming low permeable thin filter cake by using a suitable filtration control additive as an ingredient in the water-based drilling fluid systems is critical to avoid wellbore instability issues. The objective of the present paper is to review the literature on synthetic polymers as FCAs that may provide fluid-loss control at temperatures greater than 200 °F under various saline environments. Owing to the issues of in-built swelling nature of bentonite clay, poor temperature/salt tolerance of natural/ modified biopolymers, and environmental concerns related to use of lignite-based powders, there was a significant scope and requirement to develop synthetic polymers that may serve as FCAs for WBDFs. On this front, the majority of the researchers evaluated using synthetic copolymers and terpolymers using acrylamide as a backbone. Some researchers reported use of bentonite and thermally stable clays along with synthetic polymers to enhance the filtration performance. Based on the review work, it was noted that the amphoteric terpolymers in combination with the clays demonstrated stable performance in terms of fluid-loss control at high temperatures (～300-400 °F) and salinity environments (～10 wt% CaCl2). However, systematic studies that may provide physical/statistical correlations between the fluid loss performance and the design parameters such as polymer MW and degree of functional substitution have not been reported in the literature. Additionally, it was observed that there was a lack of consistency in the reviewed literature about the protocol of evaluating the fluid-loss performance of FCAs at high-temperature conditions. This review underlines that there is significant scope to evaluate various nanomaterials for any synergistic effects in presence of the synthetic FCA polymers. This research in the near future could help to further develop successful fluid systems for fluid loss control and thin filter cake at harsher temperature and salinity environments.
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    • NSTL

    A novel laboratory technique for open-hole gravel-pack design

    Jose Henrique Bitencourt ZimmermannMohammad HaftaniChenxi Wang
    11页
    查看更多>>摘要：Gravel-pack completion is implemented in the wellbores to prevent sand production and minimize formation damage due to fines migration. As higher flow velocities exist near the wellbore region, sanding and fines migration are expected to occur in the wellbore vicinity. Therefore, wellbore productivity depends on the gravel-pack performance in allowing the passage of fine particles into the wellbore while preventing the entry of sand particles into the gravel-pack. The gravel design criterion proposed in the literature has been used as a guideline for gravel design, and it has typically provided adequate sand control for field operations. This study introduces a Sand Retention Test (SRT) setup to evaluate the sand production and fines plugging in wellbores completed with open-hole gravel-pack (OHGP). The SRT testing is used to replicate the widely used experimental procedure performed for gravel-pack applications and prove the reasonable repeatability of the results with respect to differential pressure measurements and the effluent fines concentration. SRT experiments with single-phase flow were conducted on a specific formation particle size distribution (PSD), incorporating the gravel-pack and wellbore screen coupon. The application of the SRT facility for OHGP is validated against pioneering experiments in the literature. The results reasonably agree on solid production and gravel-pack impairment trends between the replication and literature test results. Besides, the repeatability test results indicate reasonable agreement between the differential pressures across the sand-pack and gravel-pack and fines production in different tests. This research validates a novel laboratory testing against a gravel sizing criterion that has been commonly used in the industry. The proposed technique can customize testing for gravel-pack design and be employed for further research on the OHGP scenarios.
      原文链接:
    • NSTL