Jilin Oilfield Research Articles

Research on Stress Sensitivity of Low Permeability Sand Stone Reservoir

In the process of low-permeability sandstone reservoir exploitation, stress sensitivity takes place with the effective stress rises gradually, which will cause permeability decline. Allowing to the condition of in-situ stress, the study and experiment on the rock core in Jilin oil field Fuxin326 oil layer are presented. The experimental results show that the stress sensitivity of this oil layer is small; the regularity of permeability changes is in accordance with exponential function. The stress sensitivity of high permeability core is larger than that of low permeability core. Moreover, experimental and theoretical analysis shows that low permeability core has a larger permeability loss than high permeability core in loading and unloading process where elastic plastic deformation of rock will happen, which is the major reason that permeability loss can not return completely.

The Damage Theory Model on Fluid-Solid-Heat Coupling of Reservoir under Process Injection

Based on the study of double porous medium, the paper provides a new model of cylinder volume element plastic yielding, which assumes that the rock mass is compressible and obeys the D-P formula, and deformation, nucleation and growing of pores and fractures are induced by stress of injection pressure and temperature. The damage variable is defined by strain porosity, and then constitutional equation of double pore medium saturated liquid-solid is set up. Taking one well of Jilin Oil Field in China as a case, the damage variable, porosity and induced stress change laws of rock strain coupling with temperature-injection are studied. The results are acquired from numerical simulation of finite element software, including induced stresses of thermal field, water flood pressure, rock stress distribution rule, together with evolving regulations of stress, damage variable and strain porosity. The numerical computation results match well with the practical situation, which shows that there is obvious elastic and plastic damage characteristic during mass water flood recovery. The new model provides a new research method and theoretical base for changes of reservoir pores and fractures during water flood exploration.

Mechanical Determination of Re-Fracture Well Create New Fracture

The mechanical distribution of refracturing rock around well is Considered, the induced stress of vertical fractured well changes in pore pressure is first to establish, taking into account the fluid compressibility, the introduction of the initial artificial fracture fluid factor, an evolution model of in-situ stress is built up for initial fracture. Consider the impact of temperature on the reservoir rock, an evolution model of the temperature induced stress model is built up, Combined with in-situ stress field, an evolution model of Mechanical determination conditions of re-fracture well create new fracture is built up. Calculation of a block of Jilin Oilfield injection wells by the three effects of stress around an oil well, the theoretical calculation results are consistent with the field.

Washing of field weathered crude oil contaminated soil with an environmentally compatible surfactant, alkyl polyglucoside

Weathered crude oil contaminated soils (COCSs), which are much more difficult to remediate than those freshly contaminated, are widespread especially at the sites of oil fields and industries. Surfactant enhanced ex situ soil washing could be used to remediate COCSs, but surfactant toxicity becomes one of the major concerns. In this study, a class of green surfactants, alkyl polyglucosides (APGs), were tested in washing the field weathered COCS with relatively high oil concentration (123 mg g −1 dry soil) from Jilin Oilfield, Northeastern China. APG1214, characterized with longer alkyl chain, was more effective than APG0810 in crude oil removal. Adding inorganic sodium salts into APG1214 solution further improved the crude oil removal efficiency (CORE). Washing parameters (temperature, washing time, agitation speed and solution/soil ratio) were investigated and further optimized integratedly with an orthogonal design. At the optimum conditions, the CORE reached 97%. GC/MS analysis showed that the proportion of small n-alkanes (C 16–C 23) in residual crude oil gradually increased, which was helpful to interpret the oil removal mechanism. Moreover, eminent effect on removal of large n-alkanes was achieved from the synergy between APG1214 and inorganic salts, which was opposite to the effect when they were added separately. This study demonstrated a promising way to remediate COCS with ecologically compatible surfactant and provided guidelines for its practical application.

ＭＥＯＲを目的とした水溶性ポリマー生産微生物のスクリーニング

In order to obtain highly talented microorganisms to be applied to Fuyu oilfield, PetroChina Company Limited Jilin Oilfield Company, where fractures and sedimentary anisotropy dominate the permeability of the reservoir, microorganisms which produce water-soluble polymer were searched for Microbial FOR by means of permeability modification. Enterobacter sp. TU-7A and TRC-322 were found among talented microorganisms which had already been obtained as gas producers, and Clostridium sp. TU-15A was newly obtained. All of these three microorganisms showed the viscosity of their cultivated solution equivalent to or higher than that shown by SP018 reported by Oklahoma University. Particularly, TU-15A showed an outstanding increase of viscosity, ca. 70cP at a shear rate of 40s-1.For simulative application of strain TU-15A to Jilin oilfield, its optimal cultivation condition and dominant growth under competitive reservoir conditions were discussed. Results may be summarized as follows.1) The viscosity of cultivated solution for TU-15A proportionally increases with the initial molasses concentration, which makes possible an estimation of economically efficient concentration of molasses for injection, and moreover, which may make possible the use of fluid of so high viscosity that its injection is impossible through a well.2) The optimum pH range of TU-15A for polymer production is 7.0-9.0. Automatic adjustment of pH to the optimum range may be done in the reservoir of Fuyu oilfield by natural dilution with brine, the pH of which is 7.7.3) Initial cell concentration of TU-15A in the culture solution for injection must be equal to or higher than 1.0×106 cells/ml for its dominant growth in the reservoir.

石油公団の実施する国際共同研究の現状とねらい

One of the functions of Technology Research Center of Japan National Oil Corporation is to promote international R&D Collaborations. A background philosophy and two categories of international collaboration are reviewed: technology introducing and sharing type, and strategic type with oil producing countries. Several projects, ongoing or in the past, of each category are explained briefly.Technology introducing and sharing type: Joint Research Consortium TRC currently participating, EOR Workshop organized by International Energy Agency, JIP's organized by Drilling Engineering Association.Strategic type: Collaborative research projects with PERTAMINA of Indonesia, TPAO of Turkey, Jilin Oil Field Administrative Bureau of China, KISR of Kuwait, King Fahd University of Petroleum and Minerals of Saudi Arabia, PDVSA of Venezuela, Abu Dhabi National Oil Company of United Arab Emirates, PEMEX-E & P of Mexico.

油層の先住微生物を利用したＭＥＯＲ研究

In MEOR field operations, injection of microorganism (s) may cause the competition between the injected microorganism and natural microorganisms in the reservoir, which may lead to unexpected results. Therefore, utilization of natural microorganisms in the reservoir for MEOR may be one of the best solution.In the present study, first of all, natural microorganisms were collected from the reservoir brine of six production wells in the target oil field, and 32 bacteria were isolated. Then, their function for MEOR were tested, and it was found that No. 12 strain produced a large amount of CO2 gas and metabolites of ethanol and acetic acid, and addition of a small amount of (NH4)2HPO4 increased the production of CO2.Huff and Puff field trials with No. 12 strain Jilin oil field, China were carried out for four wells in 1997. As a result, it was found that the oil production rate increased by 46.4% on the average of four wells for 70 day production, due to the increase of rate of production fluid, not the increase of oil cut.

A study on organic matter in different sedimentary formation from Jilin oilfield, China, by analytical pyrolysis gas chromatography (PY-GC)

A study on organic matter in different sedimentary formation from Jilin oilfield, China, by analytical pyrolysis gas chromatography (PY-GC)