Oilfield Water Research Articles

Hydrogeochemical characterization of oilfield waters from southeast Maracaibo Basin (Venezuela): Diagenetic effects on chemical and isotopic composition

Free water and water in emulsion with oil from hydrocarbon wells onshore–offshore Lake Maracaibo were extracted and analyzed. The use of classical and new chemical diagrams evidenced that Na–HCO3 and Na–Cl are the main chemical facies, whereas Na–SO4 facies was rare and revealed only in faulted areas in which shallow groundwater was involved in deep circulation. Cretaceous Ca–Cl waters were not revealed, but their imprint on some samples was traced and evidenced by Langelier–Ludwig, Brine-Differentiation and Caexcess vs. Nadeficit diagrams. These square plots, allowing a discrimination between the water contributions from the different source rocks, should be more exploited as hydrogeochemical tools in hydrocarbon exploration. Original data on monocarboxylic anions showed acetate concentration higher than ten times that of formate at sampling conditions, but speciation under deep conditions indicated a reversed activity dominance. Calculation of saturation indexes and kinetic modeling showed an active precipitation of chalcedony, kaolinite and clays, especially where the temperature was lower (T < 100 °C). Formation waters and lake water showed quite similar chloride concentration and hydrogen isotope composition. However, thermodynamic calculations at the oilfield P-T conditions revealed chlorite and illite, produced during previous diagenetic stages of Misoa sandstones, recrystallization to smectite and vermiculite in present-day stage. The diagenetic water produced in these reactions could have enriched the δ18O isotopic composition of approximately +2‰. This isotope diagenetic effect was more evident in Na–HCO3 waters, which also showed a decrease in chloride at constant boron concentration as a consequence of clay dewatering. In this regard, a new boron geothermometer useful for formation waters is also proposed:T°C=[5.1364×ln(1/B)mg/1]+5.728(±0.180)−0.164(±0.012)

Impact of stylolitization on diagenesis of a Lower Cretaceous carbonate reservoir from a giant oilfield, Abu Dhabi, United Arab Emirates

Bed-parallel stylolites are a widespread diagenetic feature in Lower Cretaceous limestone reservoirs, Abu Dhabi, United Arab Emirates (UAE). Diagenetic calcite, dolomite, kaolin and small amounts of pyrite, fluorite, anhydrite and sphalerite occur along and in the vicinity of the stylolites. Petrographic observations, negative δ18OVPDB, fluid inclusion microthermometry, and enrichment in 87Sr suggest that these cements have precipitated from hot basinal brines, which migrated along the stylolites and genetically related microfractures (tension gashes). Fluid migration was presumably related to lateral tectonic compression events related to the foreland basin formation. The low solubility of Al3+ in formation waters suggests that kaolin precipitation was linked to derivation of organic acids during organic matter maturation, probably in siliciclastic source rocks. The mass released from stylolitization was presumably re-precipitated as macro- and microcrystalline calcite cement in the host limestones. The flanks of the oilfield (water zone) display more frequent presence and higher amplitude of stylolites, lower porosity and permeability, higher homogenization temperatures and more radiogenic composition of carbonates compared to the crest (oil zone). This indicates that oil emplacement retards diagenesis. This study demonstrates that stylolitization plays a crucial role in fluid flow and diagenesis of carbonate reservoirs during basin evolution.

Current Status and Expectation of Salt Containing Waste Water Discharged from Oil Production and Its Treatment

In this paper, we review the current status about the salt containing waste water discharged from oil production. Currently, most of the waste water discharged from oil production in China has not been treated by desalination. Soilsalinization has been an important environment problem. The salt-containing composition and mineralization degree data of reservoir water in major oil and gas fields of China were summarized. It can be seen that the reported data show very different and complex distribution of salt-containing composition of reservoir water. The application of computer simulation canimprove the prediction of the analytical data. The predicted data of water and salt concentration in the soil can be used to determine the boundary condition and initial condition of the simulation, and the limit of the sampling can be thus avoided. The results of the study will provide a scientific basis for environmental protection to build the standards of the salt contents of waste water and to prevent secondary salinization of soil of oil fields.

Application of a polytetrafluoroethylene (PTFE) flat membrane for the treatment of pre-treated ASP flooding produced water in a Daqing oilfield

Pre-treated ASP flooding oilfield water produced in Daqing, China was treated by a PTFE microfiltration membrane and the removal efficiency of the main pollutants in the oilfield-produced water was studied.

Determination of boron in produced water using the carminic acid assay

Using the carminic acid assay, we determined the concentration of boron in oilfield waters. We investigated the effect of high concentrations of salts and dissolved metals on the assay performance. The influence of temperature, development time, reagent concentration, and water volume was studied. Ten produced and flowback water samples of different origins were measured, and the method was successfully validated against ICP-MS measurements. In water-stressed regions, produced water is a potential source of fresh water for irrigation, industrial applications, or consumption. Therefore, boron concentration must be determined and controlled to match the envisaged waste water reuse. Fast, precise, and onsite measurements are needed to minimize errors introduced by sample transportation to laboratories. We found that the optimum conditions for our application were a 5:1 mixing volume ratio (reagent to sample), a 1gL−1 carminic acid concentration in 99.99% sulfuric acid, and a 30min reaction time at ambient temperature (20°C to 23°C). Absorption values were best measured at 610nm and 630nm and baseline corrected at 865nm. Under these conditions, the sensitivity of the assay to boron was maximized while its cross-sensitivity to dissolved titanium, iron, barium and zirconium was minimized, alleviating the need for masking agents and extraction methods.

裂缝性碳酸盐岩油藏凝胶堵水方案优化模拟研究

In order to avoid S Oilfield water ratio rising rapidly and slow down production decline, we need to implement plugging process with polymer gel. Through researches on the mechanism of the polymer gel, and factor in elements during underground water plugging process including underground gel chemical reaction, loss of various chemical agent, adsorption and retention of chemical component, degradation of gel, and the influence to water phase viscosity from flow properties and the chemical components, etc., we can establish a movable gel three-phase seven components numerical model. By simulative calculation, we are able to get a reasonable way of gel injection and injection volume, providing an effective way to improve the effect of oil field exploitation, slow down production decline and improve recovery efficiency.

AN EXPERIMENTAL INVESTIGATION OF THE EFFECT OF SURFACTANTS ON RELATIVE ROCK PERMEABILITY

The various methods of enhanced oil recovery are developed on the background of falling rates of oil production and the introduction of hard to recover reserves in the development. The chemical methods such as acid treatment wellbottom band and the use of synthetic additives or surface-active agents become widespread. They are dissolved in injected water and they are injected into the reservoir through the system of the maintenance of reservoir pressure to reduce the surface tension of the interface “oil-water”. The introduction of the method of surface-active agents is prevented by the complexity of the dynamic changes in the physical-chemical properties of rocks, thermodynamic conditions in the reservoir in the range from water-injection wells to exploitation wells, huge amounts of water injection into the pressure maintenance system and continuous increase of the water intrusion of the developed working seam. The experimental results for the determination of the relative rock permeability of Sorovskoe oilfield are presented in this paper. The experiment was carried out in two stages: the filtration of a two component mixture without surfactant and with a reagent dissolved in an oil-field water model. The results obtained allow suggesting that the samples permeability, primarily for oil, increases for each of the simulated filtration regimes when adding a reagent. The diagram of the permeability increase has a nonlinear dependence on the rock water flooding: the higher the water content in the two-phase flow, the greater the permeability coefficient increase when using surfactants. In conjunction with the estimated economic calculation it allows suggesting that the use of a particular reagent is optimal only for a certain period of water cut which is especially characteristic for the extreme flood patterns, where the reagent use is not always justified from an economic point of view.

Поведение геллана в водно-солевых растворах и пластовой воде

The influence of storage time and temperature on the behavior of low acyl gellan (LAG) was studied by viscometry and 1 H NMR spectroscopy without salt addition. The viscometric results revealed that the effectiveness of salts to enhance gelation of gellan changes in the following order: BaСl 2 >CaCl 2 »MgCl 2 >KCl>NaCl. The sol-gel and liquid-solid phase transitions of gellan solutions were observed upon addition of oilfield water containing 73 g L -1 of alkaline and alkaline earth metal ions. The effectiveness of salts to induce the separation of liquid and solid phases changes in the sequence: NaCl>KCl>MgCl 2 »CaCl 2 »BaСl 2 . The hydrodynamic behavior of 0.5 wt.% gellan solution injected into the sand pack model with high (20 Darcy) and lower (2 Darcy) permeability is useful to model the oil reservoirs in the process of enhanced oil recovery.

A Review of Applications of Rotating and Vibrating Membranes Systems: Advantages and Drawbacks

Dynamic filtration (DF) consists in creating a high membrane shear rate by disks rotating near a fixed membrane or by rotating or vibrating membranes. The shear rate can exceed 3 105s-1 in some modules and significantly increases permeate flux and membrane selectivity as compared to cross flow (CF) devices. This paper describes several DF industrial modules and gives equations for calculating shear rates at rotating and vibrating membranes. It reviews 23 recent articles from 2008 to 2014, dealing with diverse applications: separation of microalgae from sea water by UF, clarification of rough beer, concentration of CaCO3 suspensions, treatment of dairy effluents and shipboard wastewaters, inulin extraction from chicory juice, treatment of oil field water, and separation of bovine albumin from yeast. In several applications, the maximum permeate flux at initial concentration ranged from 270 to 760 Lh-1m-2. Modules with ceramic membranes rotating around several shafts inside a housing seem to be preferable to the concept of multi-compartments modules with metal disks rotating between fixed membranes. Since the cost of DF modules is higher than that of spiral wound ones, it is better to apply DF to ”end of pipe treatment” after an initial concentration by CF.

Estimation of stature from maxillo-facial anthropometry in Tripuri population

Barium sulfate deposition on the inner surface of a tube is one of the most serious oil field problems affecting oil field water injection systems. The effects of tube length, liquid volume, deposition time, the profile of the Ba2+ concentration in the outlet and the pressure drop in the tubing were evaluated using a graphite furnace atomic absorption spectrometer (GFAAS) and pressure transducer methods. The deposition model of BaSO4 in the tube is presented using coupled mass balance and fluid flow equations. The deposition model contains two governing parameters, the kinetic coefficient and the deposition coefficient, which can be estimated from experimental data. The predictions from the simplified model for barium sulfate scale were in good agreement with experimental data and laboratory observations. In addition, it was proved that many factors are important for deposition kinetics, including the accumulated barium ion amount, the initial flow rate, the initial barium concentration and the deposition time. Scanning electron microscopy (SEM) images of the inlet and outlet of the tube reveal the deposition thickness and morphology.

Development features and affecting factors of natural depletion of sandstone reservoirs in Sudan

Abstract Most reservoirs in Sudan are medium to high porosity and permeability sandstone reservoirs, these reservoirs have been developed by natural depletion since put into production, and the development is characterized by sparse wells of high production, big pressure differential, delayed infill drilling and water flooding, and rapid investment recovery. H field, FN field and P field are bottom water drive light oil field, bottom water drive heavy oil field and stratified high pour point oil field respectively, and they are representative fields in Sudan. The production performance of the three oil fields features sparse well spacing and high plateau rate, short stable production period, rapid water cut increase and fast production decline. Commingled production results in poor inter-layer development and complicated residual oil distribution. On the basis of the above analysis, major affecting factors of Sudan sandstone reservoirs natural drive have been identified through lab experiments, field development plan and field monitoring. The high off-take rate is conducive to the increase of the contract period recovery and recovery factor; sparse well spacing based on crude mobility range and determining infill well production cutoff considering contract terms can be helpful for cost-effective development; barriers and inter-layers can be made use of to detain bottom water coning and to enhance the development effect of bottom water oilfields; and delayed water injection in stratified high pour point reservoirs has no effect on recovery factor during contract period.

Vacuum enhanced direct contact membrane distillation for oil field produced water desalination: specific energy consumption and energy efficiency

This paper presents a study for energy requirements of lab-scale membrane distillation (MD) unit. This lab unit consists of flat-sheet membrane module with two circulation pumps, heater, and cooler to study the effect of different operating conditions on both specific energy consumption (SEC) and energy efficiency (ηE) via vacuum enhanced direct contact MD method. The flux and the two parameters of energy (SEC, ηE) were measured using different temperatures, different feed flow rates, and different feed salt concentrations. The two membranes used were neat polypropylene (PP) membrane and PP/multi-walled carbon nanotubes (MWCNTs) composite membrane. The membranes were synthesized via phase inversion process, using xylene as a solvent, methyl iso-butyl ketone as a coagulant and dispersion medium for MWCNTs. The results showed that the highest ηE was 39.5 with SEC 1,649.2 kW h/m3 at flux 52.5 kg/m2 h using 15 L/min feed flow rate of synthetic feed water with salt concentration 10,000 ppm at 55°C feed temperature. On the other hand, using our prepared membrane for the desalination of oil field water, the values of ηE and SEC were 12.1 and 4,189.5 kW h/m3, respectively.

THE CALCULATION OF PARAMETERS OF THE MIXING APPARATUS WITH A VORTEX DEVICES BY METHODS OF MATHEMATICAL STATISTICS AND PATTERN IDENTIFICATION FOR THE QUALITY OIL DESALTING IN CDU

Oilfield water and oil form oil-water emulsion under existing methods of oil production. Oilfield water is heavily mineralized fluid with a high content of chlorides of sodium, magnesium, calcium, and sulfates and bicarbonates, mechanical impurities. The presence in the oil of these impurities have a negative impact on both the safe, efficient operation of equipment of oil refining installations and the ecological safety of the environment: 1) large water content rises excessively the pressure in the apparatus of distillation of crude oil; 2) salt in the form of sedimentation in pipes and heat exchangers lead to corrosive rustiness; 3) reduce the quality of secondary products of oil refining - fuel-oil residue and tar. Technological processes of dehydration and desalting is used to remove oilfield water from oil-water emulsion. Primary dehydration of oil-water emulsion is produced in the fields by settling with the addition of demulsifiers. The residual content of salts and water in oil emulsion is removed due to the desalination process. The technological process of oil desalting involves mixing the oil, water and demulsifier. Desalination process efficiency depends strongly on the degree of mixing oil, water and demulsifier. It is proposed to use mixers with vortex devices for intensive mixing. Theoretical and experimental studies aimed at improving the processes of oil treatment for refining have been done. A stochastic model of the work of mixers with vortex devices has been constructed. The criteria characterizing the work of the vortex devices for mixing of oil, water and demulsifier have been defined. Regularities of the influence of the found parameters on the quality of desalting have been identified.

Water Drive Characteristic Curve Theory of Low Permeability Reservoir

The so-called water flooding characteristic curve refers to the oilfield water injection (or natural water drive) development process, a relationship between curve cumulative oil production, cumulative water production and accumulation of fluid production. These curves have been widely used for water injection development of dynamic and recoverable reserves forecast. After many years of practical application, summed up the four kinds of water drive characteristic curve, they have a good practical significance. Recoverable reserves are important indicators of field development and also the main basis for planning and design, while the application of water flooding characteristic curve can be predicted oil recoverable reserves. Four kinds of water flooding characteristics discussed above curve are mainly applied in high-permeability oil field, which did not consider starting pressure. In fact we should consider the impact of low permeability oilfield actuating pressure gradient on the water content. Here, we deduce the formulation considering the actuating pressure. Key words: Low permeability; Water flooding; Actuating pressure

Research of the Impurities Causes in Water Injection Well in Longhop Oilfield

Due to the particularity of its percolation of low permeability reservoirs, water injection is very difficult and damage to the reservoir, especially the impurities in injection Wells, at the same time affect the injection efficiency, it will ultimately affect the recovery of the reservoir and the oilfield production. So it is necessary to carry out the ingredients and the causes of impurities in injection wells, clearing the Source for different kinds of impurity to provide the basis for reduce the impurity content in injection wells. In this paper, the author analyzed impurities particle size, composition and content in oilfield injection water In Longhop Oilfield through the indoor experiment, and with the comparison between the ion content and composition of the filtered water samples, analyzing the cause of the impurity within the wellbore. Experimental results show that in oil field water injection well, impurities particle size are mainly distributed between 2.6 and 5.4 um, impurity content mainly changes between 0.003746% and 0.017189%, the main ingredients of impurities is Fe2O3 and acid insoluble substances (SiO2). Fe2O3 mainly comes from the injection water; acid insoluble substances mainly come from the formation sand production.

Determination of sulfate and chloride ions in highly saline oilfield water by capillary electrophoresis using bilayer-coated capillaries and indirect absorption detection

Analysis of highly saline oilfield waters for anions presents challenges. Traditional analytical techniques used for such analysis tend to suffer from both poor sensitivity and selectivity due to the high concentrations of salt present in the samples. A capillary electrophoresis method was developed for the simultaneous determination of chloride and sulfate anions which is relevant to the oilfield analysis industry and of economic value. Due to the extremely high concentrations of chloride in highly saline oilfield waters, it is difficult to achieve baseline electrophoretic separation necessary for accurate quantitation. By using a capillary with a noncovalently bound bilayer coating using Polybrene, a cationic polymer and sodium dodecyl sulfate (SDS), an anionic surfactant and a buffer consisting of 50 mM TRIS, 30 mM SDS, 5% methanol and 26 mM chromium trioxide (CrO3) at pH 6.7, baseline separation (Rs > 1.5) of chloride and sulfate was achieved. To mimic possible oilfield water samples, model water solutions of 5%, 10%, 15% and 20% chloride containing low ppm sulfate were prepared and successfully analysed using the method developed. In addition, the method was applied to determine chloride and sulfate anions in highly saline oilfield water samples. The accuracy of the method developed was verified by analysing NIST certified standards of chloride and sulfate. The results obtained for chloride and sulfate with the indirect CE-UV method were in close agreement (94–100% accuracy; <2.5% relative standard deviations) with those of the certified standard analysed by ion chromatography.

Determination of inorganic anions in oilfield water using capillary electrophoresis with indirect fluorescence detection

Analysis of high salinity oilfield water presents challenges. Here we develop a method for determination of bromide, chloride, nitrate and sulfate using 8-hydroxypyrene trisulfonic acid as an indirect fluorescence probe.

Risk Assessment-Led Characterisation of the SiteChar UK North Sea Site for the Geological Storage of CO2

Risk assessment-led characterisation of a site for the geological storage of CO 2 in the UK northern North Sea was performed for the EU SiteChar research project as one of a portfolio of sites. Implementation and testing of the SiteChar project site characterisation workflow has produced a ‘dry-run’ storage permit application that is compliant with regulatory requirements. A site suitable for commercial-scale storage was characterised, compatible with current and future industrial carbon dioxide (CO 2 ) sources in the northern UK. Pre-characterisation of the site, based on existing information acquired during hydrocarbon exploration and production, has been achieved from publicly available data. The project concept is to store captured CO 2 at a rate of 5 Mt per year for 20 years in the Blake Oil Field and surrounding Captain Sandstone saline aquifer. This commercial-scale storage of 100 Mt CO 2 can be achieved through a storage scenario combining injection of CO 2 into the oil field and concurrent water production down-dip of the field. There would be no encroachment of supercritical phase CO 2 for more than two kilometres beyond the field boundary and no adverse influence on operating hydrocarbon fields provided there is pressure management. Components of a storage permit application for the site are presented, developed as far as possible within a research project. Characterisation and technical investigations were guided by an initial assessment of perceived risks to the prospective site and a need to provide the information required for the storage permit application. The emphasis throughout was to reduce risks and uncertainty on the subsurface containment of stored CO 2 , particularly with respect to site technical performance, monitoring and regulatory issues, and effects on other resources. The results of selected risk assessment-led site characterisation investigations and the subsequent risk reassessments are described together with their implications for the understanding of the site. Additional investigations are identified that could further reduce risks and uncertainties, and enable progress toward a full storage permit application. Permit performance conditions are presented as SiteChar-recommended useful tools for discussion between the competent authority and operator. © M. Akhurst et al.

HS油田注水系统腐蚀原因分析

HS油田注水系统腐蚀严重，结合注水系统的水质，分析了腐蚀原因：矿化度和温度是影响注水系统腐蚀主要因素，除此之外，清水系统的4个站点的细菌含量以及采出水的SRB、硫化物含量均是影响腐蚀速率的重要因素。 HS oilfield water injection system is corroded severely. Combined with the water quality of HS oilfield water injection system, the reasons of corrosion are as follows. Salinity and temperature are important factors affecting the corrosion rate, and in addition, the bacteria content of four sites in fresh water system, the content of SRB and sulphide of produced water are also important factors affecting the corrosion rate.

Flow cytometry as a tool for oilfield biocide efficacy testing and monitoring

Currently, oilfield biocide performance testing relies on classical microbiological culture techniques and culture-independent based methods such as ATP measurement. Although each method has its merits, there are significant drawbacks for each. For example, results from culturing require a two to four week incubation, which delays optimization of the biocide application. It also assumes that the microbes are able to grow in oilfield culture media. ATP photometry has reduced the time necessary for system optimization to one day, but there can be challenges with quantification of stressed and dying – yet intact – microbes. Flow cytometry is a technique that allows a real-time, absolute measurement of individual cells and gives insight into microbial kill mechanisms by distinguishing physiologic states other than alive or dead. Based on these advantages we show that flow cytometry may be a better alternative for biocide selection compared to culture- and ATP-based methods. Here we show that kill studies done with flow cytometry can give more meaningful and significant results compared to culture-based methods and commercially available ATP kits on pure-culture preparations and oilfield water samples.