Upstream Oil and Gas Technology最新文献

Among artificial lift systems, the most widely used method is sucker rod pumping. Since its inception in the oil industry, inefficiency in sucker rod pumping system due to gas interference is one of major concerns. The need for better understanding of gas interference during sucker rod pumping process is significantly required. Although, many models and techniques are available but there are many parameters, which need to be well studied and adequately addressed. This delineates the need to research all empirical parameters that could affect efficiency of conventional rod pump. The pump performance appears to be low in presence of gas which in extreme situation locks the pump and make the pump paralyzed completely. The models available in literature neglect mass transfer during suction process, which brings unreliable calculation of gas phase in pump. Models in literature on efficiency of pump and gas lock are studied to analyze the vital parameters and reasons for the inefficiency. The expedient analytical models to predict gas lock criteria and efficiency of conventional pump, based on liberation of gas during pumping, are established in this work. The models emphasize the importance of the fluids properties to be handled by pump, which affect the production rate while pumping with a gaseous phase. This new model considers free gas phase presence and mass transfer during working of pump. Sensitivity and comparative analysis of numerous parameters contributing to pump efficiency is established in this work. The study results provide some theoretical and analytical references for further advancements in system efficiency of conventional rod pump system and to improve economic benefits.

The production trials in the Shenhu Area have proved that commercial level of gas production might be also obtained from low-permeable silty clayey-bearing hydrates as well. The numerical gas production simulations were conducted by using the TOUGH+HYDRATE simulator for different well configurations in the conditions of the 2020-gas hydrate production test well in the Shenhu Area. Higher gas production might be obtained with the horizontal well case and the deviated well cases rather than the vertical well. However, the commercial level of gas production from the Shenhu Area gas hydrates could not be obtained only with horizontal wells.

An advanced dynamic finite element model is presented that diagnoses the downhole pump performance of sucker rod pumping systems, applicable for any pumping conditions and equipment used. The results are compared to downhole measurements and other state of the art evaluation techniques.

Existing diagnostic tools exhibit specific limitations that reduce their applicability and output quality. This paper introduces a diagnostic tool, which can predict the rod string's stress field and its movement not only at the pump plunger but all along the rod string. Moreover, this tool can account for the interaction between rod guides and tubing as well as rod string and tubing. To this end, innovative tube-to-tube contact modeling is applied. The high precision results are accomplished by running a dynamic finite element simulation. The basic principle is to evaluate the plunger load incrementally by consecutively applying restarts of each time step, fully automated and computation time optimized.

This publication shows that both the plunger load and the rod string's dynamic behavior can be determined for any given wellbore as long as the borehole trajectory and surface dynamometer measurements are known. The dynamic finite element model is evaluated for a deviated system and a vertical system equipped with two different downhole pump types. Comparing the simulation results with the available downhole measurements shows an excellent match. The the proposed solution provides a considerable amount of details about the overall system's behavior. The evaluation has shown that the performance of standard and novel downhole pump types can be successfully diagnosed in detail, which is just possible under limitations with commercial software solutions..

The novelty of the shown technique is the consideration of the full 3D trajectory, the implementation of only physical properties of the equipment used, and a realistic setup. The validation of the model output with measured downhole data indicates an excellent accuracy of the shown model.

The cost of drilling oil and gas wells is likely to be charged by billions of dollars each year due to wellbore stability problems. In engineering practice, a linear poroelasticity stress model in combination with a rock strength criterion is commonly used to determine a minimum mud weight for stable well drilling. In this paper, new models for predicting the stability of vertical wellbores using the nonlinear form of Mogi criterion and poly-axial test results were perfumed. Afterward, by applying analytical models to the real field data, the applicability of the models has been verified. From comparing the results of this nonlinear and the liner Mogi-Coulomb criterions, the impact of the nonlinearity on the wellbore stability prediction has been identified. Thus, the results of nonlinear form of Mogi failure criterion were very close to the field mud weight used to successfully drill the borehole.

Saturation Height Modelling (SHM) is an important reservoir characterization method for estimating the water saturation component which is a fraction of the total reservoir fluids in porous media. Although several methods have been used in calculating water saturation, little or no research has employed Response Surface Methodology (RSM) in predicting water saturation in field cores. In this paper, well datasets were tested with four conventional curve fitting models including Lambda, Thomeer, Leverette J, and Brooks-Corey of which Brook-Corey gave the best fit with an R² of 0.485. The RSM with the Central Composite Design (CCD) was used to obtain the mathematical and statistical relationship between the predictors and target as well as the variables’ interactions optimization. The model was analysed using Analysis of Variance (ANOVA) which validated the correlations with an F-value of 4.96, a p-value less than 0.05, and a Lack of Fit-value of 0.76 implying that the model developed was statistically significant. The RSM model gave a better fit with an R² value of 0.817 with mathematical links, almost twice that predicted by the conventional methods. Then, the testing performance of the RSM model was compared to the standard radial basis function neural network model (R² of 0.9779). The results proved that both RSM and RBFNN models’ performance was accurate and reliable and could give a precise prediction of water saturation without any conventional curve fitting parameters.

The inclusion of clay stabilizers in water-based fluids (WBFs) during drilling, imparts WBFs with clay swelling-inhibitive properties. This protects the formation from damage due to the enhanced reduction of the swelling components (clay portions) of the formation by these chemicals during drilling. With the increasing demand for ‘green’ clay stabilizers for WBFs, knowledge of their inhibitive mechanisms is necessary for their effective selection and usage. Earlier, we proposed Amino acids (AAs) as effective “green and cheap’ clay stabilizers, However, the mechanisms through which AAs and other clay stabilizers perform shale stabilization have not been adequately described in open literature. This study is a follow-up work employed to evaluate and succinctly describe all the inhibition mechanisms utilized by AAs to prevent the swelling of the reservoir formations. Furthermore, we discovered a novel mechanism for describing the inhibitive potentials between clay stabilizers in WBFs. Herein, we employed five experimental techniques alongside a modelling tool - COSMO-RS, to evaluate and describe the inhibitive mechanisms of six AA clay stabilizers. This study confirmed that the interaction of AA and the water component of the WBF is a significant factor for AAs effective stabilizing potentials. This is an addition to literature which only highlights the interactions of clay stabilizers and clay minerals for the stability of the formation. This work evaluated all the possible interactions during a clay stabilization process and utilized statistical analyses to compare the percentage contributions of all the interactions among the clay stabilizers (AAs), clay minerals and WBFs. It was revealed that 38% of the swelling inhibition potentials of AAs depend on their interactions with the water component of the WBFs. Concurrently, 28% of the AAs inhibition potentials are based on their ability to modify the surface of reactive clays, while 15% is based on AAs ability to replace the exchangeable cations of swelling clays resulting in the strengthening of the clay's cleavage spacing. Lastly, 18% of AAs stabilizing potentials are based on their ability to neutralize the reactive moieties of swelling clays. The percentage distribution reveals that the effective interactions of AAs with the WBFs significantly contribute to their effectiveness in stabilizing shale formations. This study is essential as it provides researchers with a holistic methodology to characterize and evaluate clay stabilizers.

Formation damage has a significant impact on the overall performance of the well productivity. Removal of filter cake which is deemed to be the main strategy of formation damage remediation is crucial in open hole completion with pre-slotted liner or stand-alone screen (SAS) as a mean of sand control. Without proper planning, inefficient filter cake removal can lead to tremendous consequences since filter cake can plug the sand control component. Making the condition worse, sand control component is susceptible to plugging. This highlights the importance of selecting an effective filter cake breaker that can successfully remove the filter cake through dissolution of the main solids that constitute the major portions of the filter cake which could be the weighting material, barite, or calcium carbonate. Besides that, a proper understanding of the mechanism of the filter cake breaker chemical would be very beneficial to comprehend the filter cake breaker efficiency. The laboratory study attempted to emulate the reservoir condition. Regained permeability testing using High Pressure High Temperature (HPHT) Filter Press aimed to test the ability of several commercial filter cake breakers in removing synthetic-based-mud drill-in-fluids (SBMDIF). Chelating-based filter cake breaker, meso‑surfactant-based filter cake breaker and nano-surfactant-based filter cake breaker were the samples to be tested in the laboratory work. The condition of the filter cake after being soaked statically was visually interpreted and the regain permeability was recorded. The mechanism of each filter cake breaker to remove the SBMDIF filter cake was also examined. Based on the experimental study, meso‑surfactant-based filter cake breaker was found to be more effective to remove SBMDIF filter cake compared to chelating-based filter cake breaker and nano-surfactant-based filter cake breaker.

Buried infrastructure like natural gas pipelines may be impacted by soil movement due to landslides, flood scours, fault ruptures, liquefaction, and subsidence. Subsidence induced settlement is an identified hazard for natural gas pipelines in Central California and has two components: vertical and horizontal. In the past, investigations have revealed that the horizontal displacement is more destructive than the vertical settlement since it may cause pipe ruptures. With the increase in droughts and groundwater pumping due to climate change, more land subsidence has been attributed to these factors. This study discusses the maximum impact of land subsidence on natural gas pipelines and provides design recommendations. The maximum subsidence induced settlement recorded in Central California has been applied to a buried pipeline using non-linear finite element analysis. To capture the most accurate results, 2-miles of steel pipe located in the subsidence zone is included in the finite element model and a simplified soil-pipe interaction modeling technique is used to determine the soil stiffness around the buried pipeline. Based on the results, buckling forces due to the horizontal movement of the soil on the underground pipe are more critical than the bending stress caused by the vertical soil settlement. Although the risk of failure ascribed to buckling is high, the buried steel natural gas pipeline is resilient enough to accommodate the internal forces due to subsidence.

In this experimental research, the effect of the poly acrylonitrile-co-N-vinyl pyrrolidone /zeolite composite and four types of hydrophilic and hydrophobic of nanoparticles, namely Zinc oxide, titanium dioxide, untreated multi-walled carbon nanotubes, functionalized multi-walled carbon nanotubes on the rheological and filtrate lost attributes of newly formulated bentonite mud were evaluated. This experimental study compares the drilling fluid properties including different concentrations of nanoparticles to select the most favorite agent through several laboratory tests to generate some engineering guidelines. The different concentrations of nanoparticles (0.0028, 0.0143, 0.028, and 0.143 wt%) were used to investigate the effect on attributes of rheological and mud filtration for bentonite mud. Results of experimental tests indicated that yield point property increases up to 250% with the 0.143 wt% of FMWCNTs in bentonite mud with poly acrylonitrile-co-N-vinyl pyrrolidone/zeolite composite. Also, investigating the effects of higher temperature has shown that an improvement in thermal stability can obtain by using this composite and FMWCNTs in drilling mud rheological properties such as plastic viscosity, yield point, mud filtration volume. Evaluating the effects of using novel formulated water-based mud has shown that it can increase the drilling mud rheological properties and reduce mud filtrate volume and decrease formation damage particularly under the HPHT environment.

Biobased wax inhibitors and flow improvers have become attractive due to the need to cut production cost and migrate towards more eco-friendly oilfield chemicals. Natural cashew nut shell liquid (CNSL) extracted from shells of Anacardium occidentale was chemically modified using diethanolamine and ethanolamine. Pour point of doped oil was reduced by -18 °C. Cross-polarized micrographs of crude oils analyzed using Image J software showed reduction in crystal size, aspect ratio and boundary fractal dimension. Wax area fraction decreased by 65% indicative of wax inhibition as smooth, rounded, morphologically uniform crystals formed. Shear stress and viscosity decreased by 45% and 49%, respectively.