Henan Oilfield Research Articles

Research on Oil-Water Interfacial Properties Effect of Polymer / Surfactant Binary Flooding System

The formula of surfactant(QY-3、SHSA-HN6、SS) and polymer compound system, and the interfacial characteristics between oil and water of Henan oil field were evaluated, the binary composite system formula adapt to the field was explored. The results show that the binary composite system (surfactant QY-3 and polymer 1630S) and oil-water in Henan can achieve ultra-low interfacial tension(＜10-3mN/m); If the addition agent NaCl was added to the composite system (Surfactant Ss and polymer ZL-Ⅱ or Surfactant Ss and polymer KYPAM) that the interfacial tension between oil and water can be reduced effectively.

Feasibility Study of Secondary Polymer Flooding in Henan Oilfield, China

After polymer flooding, it is necessary to find relay technology to retain oil yield. In this paper, laboratory experiments were conducted to investigate feasibility of secondary polymer flooding, in which injecting more polymer with higher concentration and relative molecular mass. It is necessary to determine enhanced recovery range and optimum concentration. With microscopic visible glass physical models, further start up of oil drops with secondary polymer can be observed distinctly. In the mean time, macroscopic heterogeneous core tests were carried out with permeability range of 2, 5 and 8. Polymer concentration effective and economical for flooding is optimized. Ii is shown that 3%~8% of further enhanced recovery and 20% decreased water cut can be obtained, and water profile can be improved to some extend after secondary polymer flooding. Thence, it is proved that secondary polymer injection after primary polymer can indeed further improve recovery and the technology of secondary flooding is feasible. Moreover, laboratory optimum concentration of 2200mg/L is determined. On the basis of laboratory results, from 2007 to 2008, filed trial with above optimum parameters were implemented. Up to 2008.12, water cut decreased from 92% to 83%, and cumulative increased crude oil of 5.71×104t.The success of secondary polymer flooding technology provides reference for the development of oil fields after primary polymer flooding in China and other regions in the whole world. Key words: secondary polymer flooding; feasibility study; microscopic mechanism; polymer concentration optimization; after polymer flooding

Conformance Control of CSS and Steam Drive Process With a Carbamide Surfactant

Abstract Based on physical modelling, this paper discusses the feasibility of injecting additives to control the conformance of the cyclic steam stimulation (CSS) and steam drive processes in the Biquan 10 Block of the Henan Oil Field. The lab test results show that waterflooding with the addition of a carbamide surfactant can decrease residual oil saturation by 4.7% and that steam drive with the addition of this same surfactant can improve the sweep volume and increase the oil recovery factor by 17.5%. Also, field application results confirmed that injecting this surfactant in the CSS and steam drive processes can increase oil production, lower steam-oil ratio (SOR) and improve the economic benefitssignificantly. Introduction The CSS process has been applied in developing the heavy oil reservoirs in the Henan Oil Field since the late 1980s. It has been clearly demonstrated that with increasing the cycles of steam stimulation, the oil production rate decreases and SOR can rapidly reach the economic limit. For improving the oil production rate and recovery factor, the steam drive process needs to be applied as a subsequent technology. However, the reservoir in the Henan Oil Field is thin and interbedded so it is a challenge to operate the conventional steam drive process. To reduce the steam channeling effect, a number of high temperature resistant plugging surfactants have been tested, but they could not achieve ideal and persistent results(1). This paper discusses the development of a new kind of conformance control agent ? carbamide surfactant. The lab testing results and field applications of the steam drive process with the addition of a carbamide surfactant in Well Group 577, Biqian 10 Block, Henan Oil Field, are described in detail below. Mechanism and Physical Modelling When the carbamide surfactant is injected into the reservoir with steam, carbamide decomposes into CO2 and NH3 under high temperatures. The decomposition can be expressed as follows: Equation (available in full paper) The physical modelling shows that, with increasing temperature and pressure, the carbamide decomposes even faster but its concentration does not affect the decomposition speed. The produced CO2 dissolves in heavy oil and NH3 can react with some acid in the oil. As a result, the heavy oil volume expands and viscosity decreases. At 50 °C, when the oil-carbamide solution (30 wt% carbamide) ratio is 4 to 1, the oil viscosity can be reduced by 73% to 80%. The single tube displacement efficiency test shows that adding carbamide solution (30 wt% carbamide) into hot water will increase the displacing efficiency by 6.5%. Field Application and Discussion Reservoir Geology and Production History Well pattern 577 in the east of Biqian 10 block was selected for the field test. The well pattern is an inverted 9-spot with injector-producer spacing of 70 m and 100 m. The pay zone is the IV-9 layer of the H-3 interval in the Hetaoyuan Formation. The basic reservoir parameters are as follows:

Laboratory Experiments and Field Tests of an Amphiphilic Metallic Chelate for Catalytic Aquathermolysis of Heavy Oil

An amphiphilic metallic chelate−aromatic sulfonic iron was synthesized for the first time, characterized by Fourier transform infrared (FT-IR) spectroscopy, and then used in catalytic aquathermolysis of heavy oil both in the laboratory and field. The laboratory results showed that this new catalyst was efficient, universal, and superior to other efficient catalysts we have synthesized before; in addition, for EX35 heavy oil, it led to a evident viscosity reduction by 90.66% at 200 °C with 14.66% in conversion of heavy contents to light contents. To evaluate the its performance, the structure and group composition of heavy oil was analyzed by FT-IR, thin-layer chromatography−flame ionization detection (TLC-FID), gas chromatography/mass spectrometry (GC/MS), 1H NMR, and elemental analysis (EL) before and after the aquathermolysis. It is found that the changes of the composition and structure of the heavy oil can lead to the viscosity reduction. In field tests of G61012 and G6606 wells in the Henan oilfield,...

Kinetics and characteristics of phenanthrene degradation by a microbial consortium

The kinetics and characteristics of phenanthrene degradation by a microbial consortium W4 isolated from Henan Oilfield were investigated. The degradation percentage of solid phenanthrene at 200 mg/L in liquid medium after 6 days of incubation was higher than 95% under the condition of 37 °C and 120 r/min by this microbial consortium. The degradation of phenanthrene could be fitted to a first-order kinetic model with the half-life of 1.25 days. The optimum conditions for degradation of phenanthrene by consortium W4 were as follows: temperature about 37 °C, pH from 6.0 to 7.0 and salinity about 8.0 g/L. It was concluded that microbial consortium W4 might degrade phenanthrene via both salicylic acid and o-phthalic acid pathways by analyzing products with GC-MS.

Isolation and characteristics of a microbial consortium for effectively degrading phenanthrene

A microbial consortium (named W4) capable of aerobic biodegradation of solid phenanthrene as the sole source of carbon and energy was isolated by selective enrichment from petroleum-contaminated soil in the Henan oilfield, China. The strains of the consortium were identified as Sphingomonas cloacae, Rhizobium sp., Pseudomonas aeruginosa and Achromobacter xylosoxidans respectively by means of genetic methods. The major metabolites of phenanthrene were analyzed by gas chromatography-mass spectrometry (GC-MS). The biodegradation percentage of solid phenanthrene at 200 mg/L in liquid medium after 7 days of growth was greater than 99%. The degradation of phenanthrene was compared between individual predominant strains and the microbial consortium in different treatment processes. The microbial consortium showed a significant improvement of phenanthrene degradation rates in either static or shaking culture. The degradation percentage of phenanthrene by the consortium W4 decreased to some degree when C16 coexisted, however it was hardly affected by C30. Furthermore, the ability of consortium W4 to remediate oil sludge from the Dagang oil refinery was studied by composting; and it was found that the consortium W4 could obviously remove polycyclic aromatic hydrocarbons (PAHs) and paraffinic hydrocarbons. All the results indicated that the microbial consortium W4 had a promising application in bioremediation of oil-contaminated environments and could be potentially used in microbial enhanced oil recovery (MEOR).

Mechanisms of Solution Gas Drive in Heavy Oil Reservoirs

Introduction Solution gas drive in heavy oil reservoirs (with viscosity in the range of 10 to 1,000 poise and API gravity in the range of eight to 15), which is often referred to as cold production, has a long production history in Canada. In a recent review paper, Dusseault et al.(1) presented the information that more than 5,000 wells in Canada have produced heavy oil by cold production. In addition to Canada, cold production from heavy oil reservoirs has been practiced in Venezuela(2), China(3), and Oman(4). Recoveries from some of the heavy oil reservoirs by cold production are estimated to be as high as 20﹪. The high recovery is often associated with a low pressure decline rate in the reservoir and the slow increase of GOR in the two-phase below the bubblepoint, as well as geomechanical effects. Recoveries in the range of 10 to 20﹪ below the bubblepoint pressure are believed unusual for very heavy oils. In this overview, we will briefly review the literature and then provide some insight into the relevant mechanisms for cold production. Literature Review An early paper by Smith(5) set the stage for the understanding of cold production from solution gas drive in heavy oil reservoirs. In his work, Smith provides an analysis of solution gas drive in heavy oil reservoirs from the examination of field data. He attributes the high efficiency of solution gas drive in viscous oils to:a significant reduction (around one order of magnitude) in the oil viscosity due to formation of small gas bubbles in the oil,simultaneous flow of continuous oil phase and discontinuous gas phase in the form of tiny bubbles,an increase in absolute permeability due to sand production, andhigh fluid compressibility due to high gas bubble density in the oil. In order to validate some of the postulations by Smith, the bulk of research has focused on the socalled pseudo-single phase model. In the pseudo-single phase model, a new terminology has evolved to distinguish solution gas drive in heavy oil reservoirs. The so-called foamy oil terminology was introduced in 1992 by Sarma and Maini(6); it was defined as a viscous (heavy) oil containing dispersed gas bubbles. Claridge and Prats(7) used the term " foamy heavy oil" and " foamy crude" mainly to imply drastic reduction in the oil viscosity due to dispersed as bubbles. The term " foamy oil" has had a wide acceptance because the oil samples at the wellhead produced from the reservoirs seem to be in the form of oil-continuous foam, with the appearance of chocolate mousse, and may contain a large volume of dispersed gas bubbles. Hu et al.(3) report that the density of the produced oil from a heavy oil pilot well from the Henan oil field in China is about 0.58 g/cm3, while the density after all the gas has left the oil (which may take several days) is 0.95 g/cm3.

A Pilot Test of Polymer Flooding in an Elevated-Temperature Reservoir

Summary We conducted a pilot test of polymer flooding in the Shuanghe reservoir located in the southeast Henan oil field, China. The target reservoir has a net thickness of 15.56 m (50 ft), an average permeability of 420 md, and a temperature of 75°C (167°F). The polymers used are two types of modified partially hydrolyzed Polyacrylamides, named S525 and S625, which have molecular weights of 16,700,000 and 19,670,000 daltons, respectively. The objective of this pilot test is to investigate the feasibility of polymer flooding for improving oil recovery in an elevated-temperature reservoir. The polymer flooding started in February 1994. Through December 1995, a total of 246 tons (about 0.5 × 106 lbm) of dry polymer had been used with an injection concentration of 900 to 1,100 ppm. The pore volume (PV) injected reached 0.2164. As a result, oil production increased by 22,000 tons (184,000 bbl) and water production decreased by 153,000 tons (962,000 bbl), which accounts for the incremental oil recovery of 3.8% and water-cut reduction of 5.6% in the test block. We estimate that, by the end of this project, the ultimate increase in oil production will exceed 63,000 tons (528,000 bbl) with the enhanced oil recovery going up to 9.8%. The yield is 0.2 tons more oil produced per kilogram of polymer injected or 0.7 barrel of oil produced per pound of polymer. We attribute the success of the pilot test to the techniques used during the implementation of the flooding, including prevention of polymer-thermal degradation, good reservoir description, and the profile modification carried out before and after the polymer injection. This pilot test illustrates a case where polymers with extra-high molecular weight are successfully injected in an elevated-temperature reservoir to control the mobility ratio and modify the permeability profile.

Why There Weren't Any Women among the Forty-four Bidders

In November 1988 our bureau decided to introduce the assets operating system at our machinery maintenance plant, and the rental-and-appointment operating system at our commercial company. Open bidding would be conducted within the oilfield for directorships and managing posts. "One stone raised a thousand ripples," and many people eagerly came forward to try their luck. Altogether, forty-four applicants decided to take advantage of this rare opportunity to display their ambitions and talents in open and equal competition. But during the application period, which lasted nearly two months, not a single woman in the huge Henan oilfield signed her name on an application form, resulting in a forty-four to nil situation.