Water In Oil Wells Research Articles

Effect of Ionic Strength on the Polymerization of Acrylamide, N‐Vinylpyrrolidone and Vinylbenzyl trimethylammonium chloride

AbstractCationic polymers are promising materials for modifying the relative permeability of water in oil wells. These materials must withstand brine and temperature without losing their viscosity; one way to achieve this is by using hydrophobic groups. Some of these groups may contain a cationic part, and when polymerized, the electrostatic repulsions of the cations greatly influence the course of the reactions. In the present work, terpolymers from Acrylamide (AM), N‐vinylpyrrolidone (VP), and Vinylbenzyl trimethylammonium chloride (VBTA) were synthesized. The effect of the ionic strength exerted by the VBTA cationic monomer and NaCl added to the reaction solution over the terpolymer synthesis was studied. Interactions between VBTA and VP were found through FTIR, 1H‐, 13C‐ and 15N‐NMR, which causes inhibition of VP during the reaction. The inhibition was suppressed when using NaCl in the reaction mixture, which improved the molecular weight and the viscosity due to the suppression of the interactions between VBTA with VP. The ionic strength due to the VBTA content also influences on the properties of the terpolymers: at higher VBTA content, higher viscosity in water is obtained and present higher decomposition temperature in TGA‐DSC analysis.

Study on injection and production of oil and water wells in steam flooding test field of thin oil reservoir

On the basis of dynamic changes of steam injection wells and extraction wells, the influencing factors of steam injection oil production in transition zone are analyzed and summarized. According to the dynamic relationship of oil-water wells, the feasibility of steam flooding in this zone is analyzed. According to the field conditions, the reasonable well spacing and injection parameters are optimized to provide reliable field data for the application of steam flooding in this zone.

Feasibility study on adjustment of injection-production system in extremely high water cut period

Entering the stage of ultra-high water cut development, affected by faults and irregular well patterns in some areas, there are problems in the development of oilfields such as imperfect injection-production systems, high oil-water wells ratio, low multi-directional connectivity ratio, and complex injection-production relationships. To this end, combined with well seismic and fine reservoir research results, the feasibility study of the injection-production system adjustment was carried out, based on the fine adjustment of the strata well pattern, and through new drilling, supplementary drilling, re-injection, re-production, etc. The well pattern connection rules are conducive to the purpose of adjustment, thereby increasing the recovery rate and improving the effect of oilfield development.

Study on the Distribution of Sand Body and Fluid in Shallow Stratum of a Development Area

This paper explores the distribution of sand body, fluid and formation pressure in the shallow stratum of a development area through MDT formation tests and logging data, which provides a basis for finding new petroleum geological reserves and preventing casing damages of oil-water wells.

Research and Field Application of Casing Return Well Treatment Technology in Fuyu Oil Field

At present, due to years of development and well pattern adjustment, there are some problems in most oil fields such as close well spacing, dense well pattern, too many oil-water wells, and changeable well conditions. In the process of overhaul, casings in some well are seriously broken, and spit mudstone is serious inside and outside the casing, so the traditional technologies such as overhaul and drawing casing, sweeping plug cannot achieve effective management purposes, and the problem of casing breaking in oil-water wells is becoming increasingly serious, which has become an unfavorable factors restricting the stable productions and efficient development of oil field. Through careful analysis of casing leap mechanism, the casing leap treatment technology has been formed in the process of continuous exploration and summary, which provides some experience and guidance for the future casing leap treatment.

Numerical simulation on heat extraction performance of enhanced geothermal system under the different well layout

China has hundreds of thousands of oil and water wells, about 30% of which have been abandoned currently. If we can convert abandoned wells into geothermal wells, it will save lots of money and reduce drilling and completion time greatly. In this paper, six enhanced geothermal system (EGS) well layout schemes are proposed based on the utilization of abandoned oil–water wells and common oilfield well pattern. Here six common injection-production well patterns in oilfield are combined to hot dry rock (HDR) production and the heat extraction performance is simulated. The results show that the injection well number and the location of injection wells have critical influence on the heat extraction performance. Under the same total injection mass flow rate, the injection well number is the key factor and the fracture area is the secondary factor on heat extraction when the HDR energy is enough. For electricity generation, the life span is 20.2, 19.2, 19.0, 19.2, 18.2 and 13.9 years, and the heat extraction ratio is 65.83, 57.35, 65.96, 62.79, 59.30 and 43.09% from case 1 to case 6, respectively. For heating demand, the life span is 30.0, 30.0, 29.9, 30.0, 29.8, and 27.7 years, the heat extraction ratio is 78.91, 69.63, 77.02, 75.92, 72.27 and 58.94% from case 1 to case 6, respectively. The total injection mass flow rate and injection temperature also have a negative effect on the heat extraction performance. Case 1 (row parallel well layout), Case 3 (four-spot well layout) and Case 4 (five-spot well layout) are a good choice both for electricity generation and heating demand. This study provides good guidance for the selection and optimization of different EGS well layout.

English

Hydraulic fracturing technology is widely used in most oil-water wells to improve production. However, the mechanism of fracturing in a reservoir with inclusion fissures is still unclear. In this study, a theoretical model was developed to determine the stress distribution during hydraulic fracturing. The line inclusion fissure was regarded as a thin bar and the stress around the artificial fracture, which is affected by a single line inclusion, was determined using the Eshelby equivalent inclusion theory. Stress intensity factors at the tip of both the artificial fracture and the inclusion were achieved, and initiation of the fracture was predicted. Furthermore, to validate the theoretical model, re-fracturing experiments were performed on a large-scale tri-axial system. The results showed that the defects reduce the intensity of the rock, which introduces the possibility that more complex fractures emerge in the reservoir. The results also showed that the fracture direction is governed by far-field stress. The obtained conclusions are helpful to better understand the mechanism of hydraulic fracturing in reservoirs.

Evaluation of chemical composition of waters associated with petroleum production using Kohonen neural networks

Chemical composition assessment of produced water in oil wells from the same producing zones was performed using Kohonen neural networks, a pattern recognition technique based on neural networks. Produced water samples from three production zones were characterized according to their levels of salinity and calcium, magnesium, strontium, barium and sulphate (mg/L) contents. Data were normalized by variance before analysis, and Kohonen maps were generated using hexagonal structure, planar shape, and training algorithms for each batch.The analysis with Kohonen neural networks allowed assessing the chemical profile of each production zone, and identifying the formation of clusters related to the individual oil wells, as well as patterns related to seasonality. Production Zone 1 revealed the presence of two distinct sample populations associated to the different oil wells from which samples originated as from two different reservoirs. Production Zone 2 presented a homogeneous cluster of samples from the same oil well, and Production Zone 3 revealed five samples clusters constituted by samples from five different oil wells from the same reservoir. It was also possible to identify samples with anomalous behavior and characterize them according to the contents of the variables involved.

Research on Corrugated Diaphragm Sensing Technique Detecting the Pressure outside the Casing

Monitoring the pressure outside casing of oil-water wells is significant to prevent and reduce casing damage. Aiming at the problem of permanently monitoring the pressure outside casing of oil-water wells, according to FBG sensing principles, FBG is packaged by FRP, pressure sensitivity program is designed, make sure strain for four bending points of FBG sensor are well-distributed, take sinusoidal corrugated diaphragm as elastic element, a monitoring sensor with temperature compensation is developed. Pressure performance calibration test of the sensor is conducted, experimental results show that the sensor has stable performance and fine temperature compensation capability, the pressure measuring range is, sensitivity is 109.

Prediction of the Occurrence of Oil–Water Countercurrent Flow in Deviated Wells

Water circulation and oil–water countercurrent flow in a deviated well has been investigated in the present article. Flow patterns for the countercurrent flow have been identified. Two practical criteria based on the transport mechanisms of a liquid layer and a liquid droplet have been developed for determining the occurrence of oil–water countercurrent flow in deviated or multilateral wells. The criteria can also be applied to determine the liquid loading-up conditions of gas wells. Well deviation, well size, and oil density are the three major factors that affect the occurrence of oil–water countercurrent flow. The smaller the wellbore size, the larger the well deviation, or the denser the oil phase, the lower the minimum oil flow rate is required to avoid the occurrence of oil–water countercurrent flow or water circulation. Excellent agreement has been achieved between the model prediction and the field and laboratory observations. A modified equation has also been proposed for determining the water droplet size in oil–water wells.

Magnesium as a modifier for the determination of barium in offshore oil-well waters by direct current plasma atomic emission spectrometry and flame atomic absorption spectrometry

It is shown that the addition of magnesium (5 mg ml–1) to samples for the determination of barium by d.c. plasma atomic emission spectrometry enhances the sensitivity of the analysis and dramatically reduces interference from calcium and strontium at both atomic and ionic emission wavelengths. In the presence of high concentrations of sodium, magnesium is a slightly less effective plasma modifier, but still allows the determination of barium with a precision that is adequate for most practical purposes. Magnesium (in both the presence and absence of sodium) also reduces the interference of alkaline earth concomitants in the determination of barium by atomic absorption spectrometry using a fuel-rich dinitrogen oxide–acetylene flame.

Das Vorkommen von Schwefelwasserstoff in Gewässern als Folge bakterieller Sulfatreduktion

In mud-samples from a great number of stagnant and fleeting waters of Switzerland presence of sulphate-reducing bacteria could be stated. Besides the two known speciesVibrio desulfuricans van Delden andVibrio Rubentschikii Baars no other sulphate-reducers were encountered. These vibrios also could be found in the sulphursprings from Baden (Argovia), Schinznach-Bad (Argovia), Lostori (Soleure) and Soerenberg (Lucerne). They are the cause for occurrence of hydrogen-sulphid in these mineral-waters. Concentration of hydrogen-sulphid in sulphur-springs does not depend upon water-temperature, but on the quantity of nitrogenous and carbonaceus substances available for nutrients and hydrogen-donators by sulphate-reducing microorganisms. Low concentration of sulphates and occurrence of hydrogen-sulphid in oil-well waters are to be considered as the result of bacterial sulphatereduction, whereas dead organic matter is the source for nutrients and hydrogen-donators.

Methods of Shutting-off Water in Oil Wells by Chemicals

Methods of Shutting-off Water in Oil Wells by Chemicals

Chemical Analyses of Some Oil-Well Waters of Russell, Ellis and Trego Counties, Kansas

Chemical Analyses of Some Oil-Well Waters of Russell, Ellis and Trego Counties, Kansas

THE SPECTROGRAPHIC CORRELATION OF OIL WELL WATERS

A spectrographic analysis of oil well water brines is described, which allows the detection and measurement of a much larger number of elements than the chemical method usually employed, with a considerable saving of time. This larger number of correlation variables have been analyzed statistically and found to give correlations in many cases where the usual chemical tests were inadequate. It is proposed that the same methods may be applied to core analysis.

Causative Agents of Sulphate Reduction in Oil-Well Waters

That inanimate organic matter reduces sulphates in oil-well waters seems to be a tradition, rather than a confirmed fact. The writer reviews the problem in the light of early and recent investigations. Biological research is suggested. A bibliography is given in the footnotes.

Sulphate Reducing Bacteria in California Oil Waters.

Edson S. Bastin has recently pointed out1 that certain bacteria are responsible for the fact that oil well waters are low in sulphates and high in carbonates when compared with the sources from which these waters are presumably derived. He was able to isolate bacteria producing such chemical reactions from Illinois oil field waters. He also sampled oil-well waters originating from the Sunset-Midway and Coalinga districts in California. The samples were cultured by us and we were able to isolate from them sulphate reducing anaerobic bacteria of the same type as had been found in the Illinois oil field waters. Not all the wells, however, showed evidence of these organisms. The methods used for culturing will be described in another paper.As the temperature and salt concentration range at which the organisms metabolize have been used by former investigators2, 3, 4 to differentiate between various types, these influences were studied. All the organisms cultured were found to grow at room temperature and up to...