Journal of Southwest Petroleum University(Science & Technology Edition)

AN APPROACH TO THE CONDITIONS FOR CONDENSATE GAS POOL FORMATION IN TARIM BASIN

ZHANG Ji ZHANG Lie-hui ZHOU Shou-xin XU Chun mei NAN Li ya

2002, 24(4): 1-4. DOI: 10.3863/j.issn.1000-2634.2002.04.001

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The conditions, in terms of hydrocarbon source, temperature, pressure, tectonic activities and sealing, for the formation of condensate gas pools in the Tarim basin are analyzed and discussed. It is concluded that the gas-generating kerogens are of both the land-derived humic type and the marine sapropelic type, withthe two types generating gas condensates at different
thermal evolutional stages. The temperature and pressure ranges for the gas condensate accumulations in the basin are 70-130℃and 35-60 MPa, respectively. The existence of favorable regional capping beds is an important factor for the enrichment of gas condensates, while later phase tectonic reworking is the major factor for the formation of secondary gas condensate pools.

A STUDY OF SEISMIC WAVEFORM INVERSION BY CHAOTIC NOISE PERTURBING

YIN Cheng PU Yong ZHOU Jie-ling XU Chuan xiong ZHENG Xiong

2002, 24(4): 5-8. DOI: 10.3863/j.issn.1000-2634.2002.04.002

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In general, geophysical inversion is a nonlinear, multi-parameter, non-onvex question. It is therefore worthy of solving geophysical inversion questions with nonlinear approaches to search for new global optimization algorithm. In the present work, the thought of chaotic noise perturbing is introduced into
seismic waveform inversion. The method is characterized by introducing a simple nonlinear feedback into the gradient descendant systems for optimization tasks. It not only maintains the fast searching speed of the gradient descendant method, but also is of the capability to get away from the pitfall of local extremum. Results show that in comparison with conventional genetic algorithm and logistic map-based chaotic optimization algorithm the proposed method is faster in computation and needs
less subjective parameters, and then is easier to lead to a global optimization.

METHOD OF EVALUATING LOW-PERMEABILITY,FRACTURED CARBONATE RESERVOIRS WITH CONVENTIONAL LOGGING TECHNIQUES

WANG Yong-jun XIAHong-quan FAN Xiang-yu

2002, 24(4): 9-12. DOI: 10.3863/j.issn.1000-2634.2002.04.003

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The key parameter in evaluating fractured carbonate reservoirs is fracture porosity. However, the evaluation of such reservoirs with conventional logging data has for the most part been qualitative. On the basis of qualitative identification, the fracture porosity of the Changxing fractured carbonate reservoir in the T gas field was determined in the present work, by calibrating log curves with core data. Results indicate a higher loginterpretation precision although available log curves were much limited. Considering the situation in many of the old oil/gas fields where log data are extremely inadequate, it is believed that the proposed method is promising in application.

TECTONIC EVOLUTION AND PROTOTYPE BASINS OF SANTANGHU BASIN

LIU Xue-feng LIU Shao-ping LIU Cheng-xin et al

2002, 24(4): 13-16. DOI: 10.3863/j.issn.1000-2634.2002.04.004

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The tectonic evolution of Santanghu basin has undergone three major stages: (1) Oceanic subduction during Middle Devonian and the early phase of Late Devonian; (2) Formation of remnant sea basin from the late phase of Later Devonian to Early Carboniferous; (3) Intra-plate tectonic evolution since Later
Carboniferous. The last stage can be further divided into four sub-stages: collision and mountain formation during Late Carboniferous-Early Permian, A-subduction and foreland basin formation during Late Permian-Triassic, stress adjustment and sag-basin formation during Jurassic-Cretaceous, and Aubduc-
tion and regenerative foreland basin formation since Tertiary.Accordingly, six different, stacking prototype basins, namely back-arc basin, remnant sea basin, fore-mountain sag basin,foreland basin, simple sag basin and regenerative foreland basin,have been formed.

STUDY ON PETROPHYSICAL PROPERTIES OF LOW-RESISTIVITY RESERVOIRS

HU Jun XUAN Guo-yong Wei Hong-yan

2002, 24(4): 17-19. DOI: 10.3863/j.issn.1000-2634.2002.04.005

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The combined use of conventional logs such as density,neutron and resistivity logs has been proven very effective in evaluating normal reservoirs. An accurate determination of the petrophysical parameters with the conventional logs for low resistivity reservoirs, however, is very difficult. This paper presents two cases of low resistivity reservoirs and low contrast resistivity reservoirs where conventional logging interpretation shows water zones, yet water free hydrocarbons would be produced. Nuclear Magnetic Resonance (NMR) has been available only as a supplement tool, to provide additional information on the productivity of the reservoir. This paper shows that in the
case of low resistivity contrast reservoirs NMR is a very cost-effective tool for helping accurately determine petrophysical properties of the reservoir.

STUDY ON CASING PROGRAM DESIGN CONSIDERING THE EFFECT OF SALT BED CREEP

XIE You-xin XIONG You-ming XU Zhi-xiong LIU Hui xin JIA Li qiang

2002, 24(4): 20-23. DOI: 10.3863/j.issn.1000-2634.2002.04.006

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Salt bed creep has been a big challenge for casing program design for deep and extra-deep wells. It is also the case in the Tarim basin, where there are very thick, gypsum-bearing salt beds in the Carboniferous formations of Lunnan and Halihatang areas and in the Tertiary formations of Yinmaili area. During drilling into these formations, sticking of tool was often the case. Shear deformation or breakdown of the casing induced by salt creeping would occur shortly after completion. Therefore, the conventional methods of casing program design cannot satisfy the needs in this basin. In the present work, a method is proposed and the companying software is developed of casing
program design for deep and extra-deep wells, with salt bed creeping taken into consideration. The method and software have been used in designing the casing program of seven wells and have been proven valid and effective.

MATHEMATICAL MODEL AND CHARACTER OF PRESSURE TRANSIENT OF UNSTABLE SEEPAGE FLOW IN DEFORMABLE DUAL-POROSITY FRACTAL RESERVOIRS

HE Guo-liang XIANG Kai-li

2002, 24(4): 24-28. DOI: 10.3863/j.issn.1000-2634.2002.04.007

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On the basis of Warren-Root model, a mathematical model of unstable seepage flow in deformable, dual-porosity reservoirs for the infinite and bounded strata isproposed. Introduced into the model are fractal parameters (dfandθ) and deformation coefficients. The model assumes that both fracture porosity and porosityare functions of pressure and spatial distance, and thus
it is nonlinear in nature. Numerical solutions to the model are obtained with the predictor-corrector method. Pressure transient character and its effect on the parameters are analyzed.

GENERAL SOLUTION OF THE PRESSURE DISTRIBUTION IN MULTILAYER RESERVOIRS

LI Shun-chu ZANG Pu-zai HUANG Bing-guang

2002, 24(4): 28-39. DOI: 10.3863/j.issn.1000-2634.2002.04.008

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This paper presented the bottom pressure performance with the three kinds of boundary conditions (infinite outer boundary, closed outer boundary, constant pressure outer boundary)and the two kinds of inner boundary conditions(wellbore storage and skin effects) in multiplier reservoirs without
cross-flow. A general formula of the corresponding Laplace space solution was not only derived from the complete analysis, but the special cases were also discussed.the results of the research shows: the theory of the multilayer well test presented in the paper has an important significance to program the application software.

COMPARATIVE STUDY OF TWO MODELS FOR CONTINUOUS REMOVAL OF LIQUIDS FROM GAS WELLS

LI Min GUO Ping ZHANG Mao-lin MEI Hai-yan LIU Wu LI Shi-lun

2002, 24(4): 30-32. DOI: 10.3863/j.issn.1000-2634.2002.04.009

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Gas produced from a reservoir tends to have liquid-phase material with it, which can accumulate in the wellbore over time when the transporting energy is low enough. The liquid thus accumulated will cause additional hydrostatic pressure onthe reservoir, resulting in a continued reduction of available
transportation energy and affecting the production capacity. In some cases, it even causes gas well to die. Many formulas related to the determination of critical rate for continuous removal of liquids from gas well have been proposed. Two of the models,as proposed by Min LI and Turner et al, respectively, are compared in this paper. The comparative study includes: (1) The shape of liquid droplets entrained in high velocity stream; (2)The drag coefficient; (3) The terminal velocity and critical rate formulae; (4) Comparative study with field data. For the easier application purpose, simplified formulas for the calculation of critical rate and production rate are also deduced and given in the paper.

EXPERIMENTAL STUDY OF THREE KINDS OF SOURCE WATER MIXED INJECTION IN SZ36-1OIL FIELD

LI Hong-jian CHEN Yi-jian WANG Shu-di HU Ling zhi LI Jun MA Xiu feng

2002, 24(4): 33-35. DOI: 10.3863/j.issn.1000-2634.2002.04.010

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The injected water samples offered by SZ36-1 oil field are seawater, sewage and formation water. The scale produced by the injection water is one of the important factors that impac jection of flooding wells and developing effect in the oil field. Analysis results of water show that the concentration of SO^2-₄is as high as 3670 mg/L in seawater, which requires special attention to the concentration of Ba²⁺in source water that mixed with seawater during flooding in order to avoid generating BaSO₄scale. In addition, there are some HCO^-₃ions in the three kinds of source water, so it is essential to consider the fact that the changing of temperature breaks the balance of water system and generates CaCO3scale. The tendency of scaling of the mixed samples of three kinds of source water is studied under the formation temperature (60℃) and the normal temperature (20℃) by the perpendicular method. Results show that the maximums of scale of the mixed samples of three kinds of
source water are very different (they are 139 mg/L and 12 mg/L) under the different temperatures. At the same time, the optimal and the worst mixture ratio of the mixed sample of three kinds of source water are obtained respectively. It provides a reliable basis for injecting mixed formation water, sewage and seawater of the oil field.

AN EXPERIMENTAL STUDY OF THE MECHANISM OF OIL DISPLACEMENT WITH CLAY COLLOIDS

LI Zhou-rong ZHOU Yuan-bin WANG Xin LI Ji yong YUAN Ming quan

2002, 24(4): 36-39. DOI: 10.3863/j.issn.1000-2634.2002.04.011

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On the basis of preliminary studies on the mechanism of oil displacement with clay colloid SMD system, this work focuses on the regularities of percolation and dispersion of clay colloids in different permeability models. The physical models used are flat sand-packs. Observed phenomena include pressure balancing between large and small pores/throats, pressure fluctuation,and emulsification-transporting. It has been noted that the advancing front of the moving SMD system would assume a fanlike shape, with a zone of dilution and dispersion occurring along the edge, and periodical break though would take place within the low-permeability layers. With the clay colloid system, oil/gas mobility ratio and sweep efficiency can be effectively improved. By modifying the formula of SMD system, can be used to formations of different ermeability.

OIL RESERVOIR IN SHENGLI OIL FIELD

MA Xiu-feng YANG Zhao-Zhong LI Zhe LI Jun ZHANG Ling-ling ZHANG Yong-ming

2002, 24(4): 40-44. DOI: 10.3863/j.issn.1000-2634.2002.04.012

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The Chenjiazhuang Reservior in Shengli Oil Field is a typically heavy and high permeability reservoir, which resulted in a relatively poor oil increment by the universal thermal-stimulation. By the geologic research and the developmentanalysis, robust water-injection according to distribution of remaining oil andhydrodynamic, matching techniques as well as careful reservoir management, were all contributed much to oil recovery,
which comes true that oil production annually held steady-going
with a bit of rise. The comprehensive water percentage was steady, the oil exploration effect was obviously improved, and the recovery efficiency increased 5.6%.

EARLY-STAGE INJECTION-PRODUCTION PERFORMANCE OF POLYMER FLOODING AND EFFECT ANALYSIS: FEIYANTAN OILFIELD

SHENG Li-jiang KANG Ren-hua YANG Ming-ling LIN Jie

2002, 24(4): 45-48. DOI: 10.3863/j.issn.1000-2634.2002.04.013

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The area within Feiyantan oilfield was under polymer injection when the total water cut reached 86.1%. As such the area claims the lowest water cut among all the areas put into polymer injection in Shengli oilfield so far. A good effect of increased oil production and decreased water cut appears after the
polymer flooding has been carried out over one year. Oil production increases from 652 t/d to 758 t/d, while total water cut decreases from 86.1% to 79.9%. And a cumulative incremental production of 2. 2×104t has been obtained. Currently the character of early-stage flooding-production performance is apparent. The practiceand research show that the important measures to improve polymer-flooding effect in the coming years should be differential management of the injection-production wells, and a balanced recovery of liquids from the wells.

FLOW BEHAVIORS OF ASP FLOODING SYSTEM IN POROUS MEDIA

YE Zhong-bin WEI Fa-lin LUO Ping-ya

2002, 24(4): 49-52. DOI: 10.3863/j.issn.1000-2634.2002.04.014

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A series laboratory experiments have been carried out in this paper to investigate foam behaviors during N2/ASP alternative injection, especially its flow behaviors under different flow rate and pressure conditions. Experimental results show that the formation and flow of foam were seriously affected by velocity and pressure. High flow velocity makes gas channeling happen,
and low flow velocity makes the difficulty increase of foam propagating along the displacement. Low pressure is beneficial to generate stable foams. Once foam formed, its flow resistance increases and mobility decreases notably. In the process of N2/ASP alternative injection, the foam generated in the input area will propagate along porous media at the displacing of viscous fluid.

STUDY OF A NEW SURFACTANT WITH HIGH MOLECULAR WEIGHT

SUN Li-li YANG Xu YANG Shi-guang

2002, 24(4): 53-55. DOI: 10.3863/j.issn.1000-2634.2002.04.015

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High molecular weight surfactant is a very important polymer material in daily life. These materials have some special characteristics (high molecular weight and lower surface tension), so that they could be used in lots of area. Using three different kinds of monomers, acrylamide, acrylic acid, methyl ethacrylate, a high molecular weight surfactant has been synthesized and the erformance of this surfactant has been measured such as intrinsic viscosity, surface and interfacial tension.Although the ability of decreasing surface tension of the surfactant is not better than that of low molecular weight surfactant,some special characteristics of the high molecular weight surfactant have made it more useful in lots of area.

CURRENT STATUS OF APPLICATION FOR MATERIALS AND NANOTECHNOLOGY

LI Fu-sheng DUAN Ming WANG Zhou-yu JIANG Zheng-ju HU Xing-qi

2002, 24(4): 56-59. DOI: 10.3863/j.issn.1000-2634.2002.04.016

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Nanotechnology is a branch of engineering that deals with the design and manufacture of extremely small electronic circuits and mechanical devices built at nano level of matter. It was first appeared at the later of the 20th century. Nanotechnology spans a wide variety of disciplines such as physics, chemistry, applied mathematics, material science, computer simulation/design science, electronics, engineering, biotechnology, genetics, protein engineering, biochemistry, biosciences. The properties of electronics, mechanics, magnetic and optics of nanometer materials have been changed greatly because of their particular surface effect, volume effect and quantum size effect. Nanotechnology was applied successfully in environment protection, ceramics,
textile, lubricant, electronics and information, chemical engineering, bioengineering and pharmacy, coatings, energy, auto and aviation after development of past several years. So nanotechnology has become one of the hottest topics in the scientific research field and are regarded as another industrial revolution in the 21th century.

PROPERTIES OF STABILIZERS FOR FOAM FLOODING

YANG Yan PU Wan-fen ZHOU Ming

2002, 24(4): 60-62. DOI: 10.3863/j.issn.1000-2634.2002.04.017

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The foamability of sulfate foaming agent and its stability has been evaluated by a Waring Blend Method when adding respectively four types foam stabilizers. The viscosity decrease of the four foam stabilizers solution with the increase of temperature and salinity has been investigated. And hydrophobically associating polymer and its concentration are optimized. Results show that the foam solution in which the hydrophobically associating polymer is added has stronger foamability and its foam has longer half-life. It has good applied prospects in foam flooding.

SYNTHESIS OF POLYFERRIC SILICATE SULFATE FLOCCULANT

WAN Li-ping ZHAO Li-zhi MENG Ying-feng

2002, 24(4): 63-64. DOI: 10.3863/j.issn.1000-2634.2002.04.018

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A polyferric silicate sulfate(PFSS) flocculant has been prepared by using Na₂SiO₃、H₂SO₄and Fe₂(SO₄)₃as raw materials according to compound co-polymerization.The pH value , SiO₂content and temperature have different effects on the process of silicate preparation.The influence of molar ratio of Fe3+/SiO₂on the stability of PFSS and removal rate of CODcr has been
studied.Results have shown that optimally-prepared-PFSS has more advantages than PFS and PAC on decoloration and removal rate of CODcr , and has widely applied prospects.

RESEARCH ON MODIFIED BENTONITE BY CARBON-ENTRAINING ROASTING METHOD

CHEN Ji RAO Xiao-tong XU Yuan

2002, 24(4): 65-67. DOI: 10.3863/j.issn.1000-2634.2002.04.019

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A new method on bentonite modification by carbon-entraining roasting has been presented. The optimum conditions for bentonite modification were determined by the experiments.
The effect of improvement was evaluated by de-phenol efficiency in aqueous solution. Comparing with directing roasting method, the bentonite absorber made by carbon-entraining method has stronger adsorptive capacity, its dephenol efficiency raises about 16%. The absorber is easy to separate by sagging after treating waste water, and the recovered absorber is reusable by activation at 600℃. The modified bentonite by carbon-entraining roasting method is a good organic wastewater treatment agent that is cheaper and does not cause secondary pollution. Besides, it can be used as a catalyst carrier because the modified betonite has a stable structure and large amounts of specific surface.

SYNTHESIS OF DIMETHYL FUMARATE BY1-METHYL-3-ALKYLIMDAZOLIUM/AlCl3CATALYST

LIU Jin TAN Nai-di ZOU Chang-jun

2002, 24(4): 68-70. DOI: 10.3863/j.issn.1000-2634.2002.04.020

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In this paper, dimethyl fumarate was synthesized by isomerization and esterificatoin of maleic anhydride and methanol under 1-methyl-3-alkyl-imdazolium/AlCl3catalysts. The process of one step method was developed and optimized. The reaction temperature, amount of the catalyst, reaction time, material molar ratio and reaction time were optimized by the method
of sequential discriminate procedure for design of experiments.
Experimental results have indicated that 1-methyl-3-alkyl-imdazolium/AlCl3can catalyze the isomerization of maleic anhydride and esterification of fumaric acid, and the optimum conditions are: the molar ratio of catalyst to maleic anhydride is 0.17,that of methanol to maleic anhydride 4.01, the reaction temperature 93.0℃,the reaction time 5.0 hours, and the yield of dimethyl fumarate can reach 90%.

CONE-LOSING INDICATOR REPRESENTS DIRECTION OF CONE RETENTION TECHNIQUE

YANG Ying-xin ZHU Qiang LIU De-ming YANG Jian-zhong LIN Min SONG Dao-jie

2002, 24(4): 71-74. DOI: 10.3863/j.issn.1000-2634.2002.04.021

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Decreasing the probability of cone-losing of rock bit by improving the cone retention technique, it should have quite significant effect on reducing cost of drilling and increasing bit utilizing efficiency. This paper summarized the development history of cone retention or cone-locking technique of rock bits.
Principles and characteristics of several typical configurations,ball retainer, snap ring retainer, threaded ring retainer, and trapped ball cone-losing indicator, were described respectively.A new cone-losing indicator design, trapped rollerindicator,which utilizes the sharp changes of both twisting moment and ROP of bit as alarm signal, was introduced and analyzed. The
simulative drilling test have proved that this new technique have an ability to inspect the bearing clearance exactly, and the trapped roller will increase the twisting moment and decrease the ROP of bit by locking the cone utomatically when the critical clearance is reached.

INFLUENCE OF THE PIPE INCLINED ANGLES ON THE EXISTING REGION OF THE STRATIFIED FLOW IN GASLIQUID COMBINED PIPELINES

LIU Wu WANG Kai-xiong LIANG Dang-guo

2002, 24(4): 75-77. DOI: 10.3863/j.issn.1000-2634.2002.04.022

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To provide the theoretical basis for practical production and the design of two phase separators, this paper simulated the existing region of the stratified flow under different pipe inclined angles and the inclined angle of maximum region for stratified flow in the pipeline operation conditions was presented. The stable criterion for the stratified flow interface was derived from Kelvin Helmholtz instability theory, and the transition from stratified flow to annual flow presented by Barnea was adopted in the present papers. The results show that: the stratified flow in the upward pipelines almost did not exist; with the angle under the downward pipeline increasing, the existing region for
stratified flows gradually increased, and quickly decreased after exceeding the maximum region, and even disappeared; The optimal separating efficiency can be obtained when the inlet inclined angle of two phase separators is about 30 degree.

OPTIONAL TIME ANALYSIS OF OIL WELL OPERATION

CHEN Wu ZHANG Ming-Quan ZENG Gao-Feng ZHANG Nai-xin

2002, 24(4): 78-80. DOI: 10.3863/j.issn.1000-2634.2002.04.023

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Oil well always follows the production rate decreasing and the containing water increasing from the beginning of the development to the well closed not until it is no economic value. Especially, it is developed after the middle development term, the crude oil production rate was declined quickly and the contained water was raised quickly. The measurement of the increased
production was necessary for the production decrement to be delayed and the contained water increment to be controlled, it will enhance the life of the oil well economy. The cost will gradually be increased when the oil well is production with the time lose.It will make the economic benefit maximum in the whole oil well life when the oil well benefit was equal to the cost by some
measurements.

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