Day 1 Wed, June 20, 2018最新文献

{"title":"Optimization of Scale Treatment Program for Offshore Field Operations with Presence of Iron","authors":"Dong Lee, P. Srivastava, P. Stead, Johnathon Brooks","doi":"10.2118/190742-MS","DOIUrl":"https://doi.org/10.2118/190742-MS","url":null,"abstract":"\u0000 The presence of various levels of iron can be found in field brines primarily due to the mineralogy of the reservoir or from corrosion byproduct (Zhang 2015). The adverse effect of the presence of iron on the performance of scale inhibitors (SI) is known, and if left untreated, can lead to plugging of well tubing and pipelines. It can also cause fouling of separators; resulting in costly remediation and loss of production and revenues.\u0000 For the asset under study, traces of carbonate scale and iron sulfide were detected throughout a topsides production system. It was suspected the carbon steel production tubing was corroding over time and the byproduct was reacting with hydrogen sulfide from the souring reservoir. There are a number of well-developed methods that can be implemented to treat corrosion, bacteria, and dissolve the iron sulfide downhole; however, none of these application methods were available for this production system.\u0000 This paper will discuss the findings from laboratory testing for carbonate and sulfate scales in the precence of significant levels of iron. In order to select a proper scale inhibitor and the minimum effective concentration (MEC) for this system, a variety of chemistries were screened. Five scale inhibitors were selected for the testing, as shown in Table 1. The findings of the study show, Inhibitor D performed the best in the presence of iron at operationally viable dose rates in both static and dynamic testing conditions favorable for CaCO3, FeCO3, and BaSO4 precipitation.\u0000 Table 1 Scale Inhibitor Chemistry Scale Inhibitor Chemistry A DTPMP − Diethylenetriamine penta(methylene phosphonic acid) B BHMT − Bis(Hexamethylene triamine penta) phosphonate scale inhibitor C AEEA − Ethylyethanolamine phosphonic acid E AMPS/AA − (2-methylpropanesulfonic acid and acrylic acid) copolymer based scale inhibitor F TEA − Triethanolamine phosphate ester","PeriodicalId":445983,"journal":{"name":"Day 1 Wed, June 20, 2018","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131712436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of an UV-Vis Spectrophotometric Method for Accurate Determination of Aqueous Sulphides in Exotic Scale Studies","authors":"Y. Alduailej, L. Boak, B. Al-Harbi, A. Graham, K. Sorbie, H. Oduro, M. Al-Khaldi, S.. Alqathami","doi":"10.2118/190702-MS","DOIUrl":"https://doi.org/10.2118/190702-MS","url":null,"abstract":"\u0000 An analytical technique was developed to directly determine the concentration of aqueous sulphide in exotic scale studies. The technique is based on measuring the absorbance of sulphide samples in a copper reagent using an ultra-violet visible (UV-Vis) spectrophotometer. Calibration curves, generated using stock sodium sulphide solutions, were compared and validated against earlier reports in the literature.\u0000 The instantaneous reaction of a stirred (1000 rpm) sulphide solution and a copper reagent produces copper sulphide nano-particles, which turn the solution colour from light blue to brown. Increasing concentrations of sulphides give more intense shades of brown, resulting in increased absorbance values when analyzed by UV-VIS at a wavelength of λ = 480 nm. The absorbance readings are proportional to the sulphide concentrations in the samples, thus generating a calibration curve.\u0000 The repeatability of these absorbance measurements has an average standard deviation of 1.9% and a correlation coefficient (R2) of 0.9998 over a range of 7-386 mg/L sulphide species in synthetic brines. The determination of sulphide concentrations from absorbance readings using a 2nd order polynomial equation reveals average variations of ±1.2 and ±9.67 mg/L over the ranges of 7-70 and 105-386 mg/L, respectively. Furthermore, this technique was able to determine excess sulphide concentrations in solutions containing sulphide scale particles, as long as only clear filtered samples were analyzed. An alternative copper chloride reagent was used to prevent the formation of sulphate scale when barium or strontium ions were present in the brine being examined.\u0000 Comparing the results from the new detection method against the currently used technique reveals higher accuracy and practicality for the straightforward UV-VIS technique over the ICP analysis of quenched solutions. The new detection method allowed for the determination of any oxidative effects on the sulphide solutions, which is not identifiable using ICP.","PeriodicalId":445983,"journal":{"name":"Day 1 Wed, June 20, 2018","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123141564","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbonate and Sulphide Scale Prediction Modelling in Auto-Scaling Processes: Procedure for the Calculation of Reservoir Fluid Compositions and Scale Profiles in Production Systems using Topside Data","authors":"Duarte Silva, K. Sorbie, Giulia Ness, E. Mackay","doi":"10.2118/190711-MS","DOIUrl":"https://doi.org/10.2118/190711-MS","url":null,"abstract":"\u0000 Carbonate and sulphide scales can form in CO2 and/or H2S-rich environments in a process which we refer to as \"auto-scaling\", i.e. these scales form in the produced brine due to a change in conditions such as pressure and temperature, not due to brine mixing. Particularly in production systems, carbonate and sulphide scales can form due to the evolution of CO2 and H2S from the aqueous phase to the gas phase caused by a pressure decrease. Carbonate scale formation in this manner is broadly understood; however, there are details of precisely how this occurs in auto-scaling processes which are not widely appreciated.\u0000 Measuring the water composition at surface locations (e.g. at the separator) does not give a full indication per se of the amount of scale that has precipitated upstream of the sampling point. However, the composition of the water before precipitation occurs is required for predicting the scaling potential of the system, and this information is seldom available. In this paper, we propose a model that accounts for this issue, and that accurately calculates the carbonate and sulphide scaling profiles in CO2 and/or H2S-rich production systems by knowing only commonly available surface data – i.e. pressure, temperature, and fluid compositions (water, gas, and oil). A rigorous workflow which can do this calculation using any aqueous scale prediction model along with a PVT Model has already been published by the authors (Verri et al, 2017a). The current paper describes a new model to do these calculations which also includes an approach for estimating both the \"correct\" scaling case within a range of cases up to the \"worst case\" carbonate scaling scenario.\u0000 A scale prediction model has been developed to include a three-phase flash algorithm (using the Peng-Robinson Equation of State) coupled with an aqueous electrolyte model (using the Pitzer equations as the activity model). This model is used to run a demonstration example showing the procedure to calculate accurate auto-scaling profiles in CO2 and/or H2S-rich production systems, which is based on building a sensitivity analysis on the ions directly involved in precipitation reactions. We also note that auto-scaling profiles in production systems are commonly obtained by sectioning the production system – either by parameterising depth with pressure and temperature, or by selecting specific locations (e.g. DHSV, wellhead, etc.). Then, established guidelines to treat scale (or not) based on the calculated saturation ratios and precipitated masses of scale can be applied. We show that such an approach is not optimal and that it can lead to under or over-estimation of scale treatments. Furthermore, building on our previous method (Verri et al 2017a) we propose an approach to model the cumulative amount of scale formed under full equilibrium conditions, which is not dependent on how the production system is sectioned. By doing so, the correct amount of scale formed in the production system is","PeriodicalId":445983,"journal":{"name":"Day 1 Wed, June 20, 2018","volume":"108 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124884548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Introduction of Kinetic Effects into the Thermodynamic Modelling of CaCO3 Scale Precipitation","authors":"Duarte Silva, K. Sorbie, E. Mackay","doi":"10.2118/190737-MS","DOIUrl":"https://doi.org/10.2118/190737-MS","url":null,"abstract":"\u0000 Calcium carbonate (CaCO3) scale can form through an \"auto-scaling\" process in production systems with a CO2-rich environment due to fluid (water/oil/gas) depressurisation. Thermodynamic modelling is used to estimate the amount and severity of CaCO3 scale precipitation in this context in order to design scale inhibitor or other types of treatments. However, field experience has indicated that thermodynamic calculations often lead to an overestimation of the calcite scale problem. One possible source of this discrepancy may be due to kinetic effects; i.e. that the calcite is somewhat oversaturated (Saturation Ratio, SR >1) but the driving force is not sufficiently large and so the deposition is kinetically \"slow\". The industry response to this situation has been to come up with some simple heuristics based on field observations, and \"rules of thumb\" have been developed to account for this apparent overestimation of calcite deposition. The central objective of this paper is to try to address the problem of using such an arbitrary field procedure for calcite scale prediction by introducing the kinetics of calcite deposition in a thermodynamically consistent manner. We view the calcite auto-scaling system as one which moves from SR < 1 (non scaling) incrementally to one that is slightly supersaturated (SR slightly > 1). By making the deposition rate a function of SR, this would give slow rate of deposition initially, but as the system moved into the more scaling regime in the production system (SR > 1) then the deposition rate would increase. However, throughout the system, this kinetic formulation must limit correctly (i.e. it must be consistent with) the underlying equilibrium thermodynamics of the full brine/oil/gas system. Thus, we replace the idea of using heuristic estimates of when calcite scaling occurs by one where an estimate (or measurement) of the kinetics is made; indeed, a range of kinetics rates can easily be run to give an envelope of calcite scaling profiles in the wellbore and throughout the production system.\u0000 In this paper, we present a model that incorporates a fully consistent kinetic formulation into a general thermodynamic scale prediction model. This model can then calculates scaling profiles in production systems considering both kinetic and thermodynamic effects. In particular, a rate law for the precipitation of CaCO3 based on the respective degree of super-saturation is coupled with the Heriot-Watt FAST Scale Prediction model (HW FAST). HW FAST uses the Pitzer equations and the Peng-Robinson Equation of State to model, respectively, the aqueous and hydrocarbon phases (gas and oil), and it has been developed to calculate CaCO3 scaling profiles caused by a de-pressurisation effect in CO2-rich production systems.\u0000 First, we present an equilibrium thermodynamic example calculation showing that CaCO3 scale precipitates in CO2-rich production systems due to a de-pressurisation effect, and that precipitation is more severe tops","PeriodicalId":445983,"journal":{"name":"Day 1 Wed, June 20, 2018","volume":"126 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116094000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Procedures that Time Forgot: Sample Preservation, Back to Basics","authors":"C. Johnston, M. Jordan","doi":"10.2118/190734-MS","DOIUrl":"https://doi.org/10.2118/190734-MS","url":null,"abstract":"\u0000 A key part of the oilfield scale management toolbox is the ability to determine the concentration of residual scale inhibitors and scaling ions in produced waters. This data is essential to providing correct recommendations for how to manage and inhibit scale in a particular system, as well as monitoring the efficacy of scale management processes already in place.\u0000 The progression of analytical techniques over the last two decades has provided enhanced methods for accurate detection of ions and scale inhibitors to low limits of detection, however, correct detection of analytes present in a sample in the laboratory does not necessarily equal characterisation of the analytes in-system as they were present at the point of sampling.\u0000 The collation of a range of preservation techniques, each appropriate to a different group of analytes, forms the basis of this paper. The results of several field applications of incorrect sample preservation are outlined and the alternative preservation technique used to correct the analysis will be detailed.\u0000 The implication of using the correct preservation technique will be clearly shown to have an impact on scale management where it would lead to reduction of over treatment, leading to increased revenue, whilst also eliminating incorrectly scheduled early well interventions.","PeriodicalId":445983,"journal":{"name":"Day 1 Wed, June 20, 2018","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130751185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}