Petroleum Engineering Research Team

Petroleum Engineering Research Team covers fields of drilling & completion, production and reservoir engineering research and study, and controls the experimental laboratory on petroleum engineering. The mission of the research team is to reply oil & gas industry's subject and problems promptly attending basic R & D technology on above research fields and also to take oil & gas industry's interest in advance.
The research team has advanced mainly basic R&D, collaborated R&D with private companies and also with oil & gas producing countries.

(1) IOR/EOR Technologies
A. Research on Gas Flooding
The asphaltene precipitation during CO2 injection was investigated for a Middle East crude oil through the phase behavior studies and the coreflood tests. In the phase behavior studies, a light-scattering technique with near infrared was used to determine the onset pressure of asphaltene precipitation of oil-CO2 mixtures. The amount of the precipitated asphaltene was measured at various CO2 concentrations and pressures. The miscible CO2 and immiscible associated gas coreflood tests were conducted using carbonate core. The larger amount of asphaltene precipitation was recognized in the upper side of core in case of the miscible gas flood test. In case of immiscible gas flood test, asphaltene precipitated throughout core, but the amount was approximately half of that of miscible flood test. The effective oil permeability after miscible flood test reduced 20-25% from the original value(before the flood)and this is caused by the effect of the asphaltene precipitation.

B. Fundamental Study on Air Injection for Application to Light Oil Reservoir
We have conducted study of air injection process since 1999. The Aim of our study is to understand how to apply air injection process to a field. Three items were carried out so far. First to get more accurate data for thermal simulator, the combustion tube(CT)test was conducted again with Japanese oil sample, which was conducted CT test last year. Next to consider the possibility of miscible−flooding in the air injection process, some interfacial tensions between flue gas(N2 85mol% CO2 15mol%) and Japanese oil were measured. For the last time we also try forecasting oil production in the field using compositional simulator.

(2) Core & Fluid Analysis Technology
A. INCELA : Concept of Integrated Core Evaluation Laboratory
The purposes of this research is application of new technology to core analysis, to conduct　the case study for the analysis on fluid flow behavior and to build a reliable all-around core analysis　system. We are now advancing to build the system under the concept of INCELA(Integrated Core Evaluation Laboratory). This concept includes not only preparation of the advanced and precise methods and equipments for core analysis, but also the upscaling and core simulation technique to obtain more appropriate Kr/Pc data for reservoir simulation. For this purpose we have introduced the reservoir condition steady state type relative permeability apparatus(XRP-500) and the X-ray CT scanner system with high speed helical scanning and data treatment(Aquillion). Using these equipments, it is expected that more accurate flow behavior in heterogeneous core under reservoir condition will be investigated.

Reservoir condition steady state type relative permeability apparatus

X-ray CT scanner system

B. Application of MRI Technology for Core Analysis
It is difficult to understand the mechanism that causes unexpected fluid flow behavior due to the heterogeneities of reservoir rocks such as a carbonate rock without grasping heterogeneous distributions of petrophysical parameters. Although the wettability is of particular importance, no method with current technology can provide its spatial distribution. MRI is expected to provide such wettability distribution with much less time consumed for the experiment than Amott and USBM tests. Prior to the methodology development of wettability distribution, this study shows the workflow to improve signal to noise ratio(S/N ratio) which can be reduced by magnetic susceptibilities of rocks and the evaluation on porosity and pore size distribution using MRI.

(3) Research of the Optimization for Drilling Operation - Development for the Cuttings Transport Simulator
JOGMEC/TRC and PDVSA/INTEVEP of Venezuela and Tokyo University were jointly developing the technology related to underbalanced drilling(UBD). The final deliverables of the project by March 2002 include ; a mathematical model, a numerical model, a computer software, closure relations, and closure model. We carried out the cuttings transport experimental study with using the Cuttings Transport Flow Loop System(CTFLS)in Kashiwazaki Test Field. From 2002 to 2003, JOGMEC/TRC and Tokyo University with support of Tohoku university performed to develop and improve the transient cuttings transport simulator with inclined & horizontal well including extended reach well(ERW). It was getting close to the level to be able to apply for actual well. This year, we performed the cuttings transport study for ERW to raise practical use. As the application way of this simulator in future, we'd like to contribute to the operating company has highly awareness of hole cleaning in terms of cuttings transport.

JOGMEC Multiphase Flow Test Facility

The objectives of this research are to enhance our understanding through experimental and theoretical studies and to develop reliable and robust simulation models for multiphase flow in wellbores, flow lines, pipelines, and equipment.
The trend in multiphase flow modeling is leading toward to use of mechanistic modeling from experimental and/or empirical approaches. This is because the use of mechanistic model is expected to improve both its accuracy and extrapolation capability to any operating conditions.

For further improvement of the models, the experiments of oil-water flow in pipes are under progress.

Dynamic Field Tester Down Hole Coupon

Many oil and gas fields are being operated under production corrosive conditions with the presence of corrosive gases such as Hydrogen Sulfide (H2S) and Carbon Dioxide (CO2). To mitigate their negative impacts on field operation, corrosion resistant alloys (CRA's) are commonly used. However, the selection of an appropriate CRA for a given corrosive environment requires much engineering work, particularly when both H2S and CO2 exist in high-pressure gas wells. Under such a condition corrosion mechanism becomes complex and is affected not only by partial pressures of H2S and CO2 but also Cl-, pH, temperature, and flow behavior of the producing fluids.

To cope with such sour environments, use of stainless steels or Ni-based alloys would be considered. There are many types of CRA's available in the market and products divided into numerous categories. Operators tend to select a CRA, based upon the severest environment expected, meeting both operational and safety requirements to ensure that no corrosion related problems such as Sulfide Stress Cracking (SSC) would occur during the production life of wells. However, there is a second thought that the selected CRA may be over graded for the given condition and this could have created significant impacts on project economics.

Therefore new corrosion evaluation methods, Dynamic Field Tester (DFT) and Down Hole Coupon (DHC), were applied to this project. These test conditions were more similar to actual well conditions than conventional laboratory tests. In addition, a new laboratory test methodology reflecting the effect of water-cut on corrosion rate was also introduced. Corrosion Rate Break-point (CRB), the point where corrosion rate increases sharply, became evident in the laboratory test.

Joint study team which is composed of JOGMEC, Sumitomo metals, JODCO summarized the test results mentioned above and proposed the new material selection methods for gas-condensate wells to ADNOC in November 2004.

• The Effect of Acetic Acid on Corrosion Behavior
Currently attention is paid to the effect of organic acids, especially acetic acid on CO2 corrosion. In J-TUBE MATE, which is the tubing material selection software developed by JNOC and Nippon Steel Corporation in 1998, acetic acid is worked out as behaving that acetate consumes hydrogen ion through an ionization equilibrium. As a result of that, J-TUBE MATE judges that corrosion rate decreases as pH increases by partially being acetic acid. This processing doesn't seem to be realistic. If it is added as pure acetic acid molecule it is inferred that pH decreases and corrosion is promoted by releasing hydrogen ion. Eventually behavior of acetic acid is very complicated in a well depending on temperature, water-cut, and material's surface conditions. According to the requirement mentioned above, JOGMEC consulted Huazhong University of Science and Technology in China to investigate effects of acetic acid on CO2 corrosion from the viewpoints of acetate and acetic acid by changing temperature and materials.

(6) Offshore Oil and Gas Field Development Technology
　 Offshore oil and gas production extended its water depth range to 2,000 m in the year of 2002. This has been achieved by the innovative technical development of floating production system and Subsea Production System (SPS).

Among the existing floating production systems, it is considered that FPSO and SPAR are and will be the most feasible applications to ultra deepwater over 2,000 m. FPSO with Compliant Vertical Access Riser (CVAR) is a unique concept that can offer the workover capability and can eliminate the expensive flexible risers with use. CVAR is composed of steel rigid pipe and buoyancy members. Vortex Induced Vibration (VIV) caused by the wave and current is the important phenomenon because of the possible fatigue effects to the riser.

Decommissioning of the offshore oil ands gas production systems is one of the most serious problems, and many R&D are being carried out to minimize its cost that can applicable the latest international decommissioning standards and regulations.

The following researches have been executed based on the above states of arts:
1) System construction of engineering tools,
2) Development of cost estimation algorithm for natural gas liquefaction FPSO,
3) VIV analysis of CVAR for Workover-FPSO, and
4) Development of cost estimation algorithm for offshore production system decommissioning.

Advance of Deepwater Development Concept of CVAR-FPSO

(1) Technologies for Efficient Drilling Operations
A. Development of High Performance Bit for Hard Rock　

A prototype bit

From a viewpoint of bit application in the fields of Japan, Vietnam etc., current roller bit is not effective on account of low ROP and short bit life in hard, abrasive rock such as volcanic and granite rock that is now being drilled. The cause of low ROP and short bit life is thought damage and worn of the tip and gage part of bit in short time. The main purpose of this research is that by conducting a research and development about high resists abrasion material for roller bit, to extend bit life and improve bit’s performance. Furthermore to make progress bit’s ROP of these areas and contribute the reduction of drilling cost, by acquiring and analyzing the data of drilling and logging in such formation. In 2003, a field trial for developed material with prototype bit was carried out in the GTI Catoosa test field in USA. As a result, high resistant to abrasion of the new material was proven. However the materials need to be improved in resistant to fatigue failure. An improved material was manufactured and tested in laboratories for verification of the improvement.

B. Technology for Improvement of Wellbore Stability of Shale Formation
In the collaborative research program on “Technology for Improvement of Wellbore Stability of Shale Formation”, we have studied the mechanism of shale instability problems and effective counter-measures of them for the improvement and cost reduction of drilling operations since 1999. The fiscal year 2003 is the last year of the project. During the first three years, fundamental knowledge about the mechanism was investigated with numerical simulation techniques and measurement techniques of Geomechanical parameters. In the last two years, the project stepped in the application phase and we achieved the targets of the project; to utilize comprehensive engineering approaches for the wellbore stability in oil fields, in which practical methods to eliminate the problem were found, and basic and fundamental knowledge of the science of shale failure were obtained.

(1) PEMEX-JOGMEC joint study
PEMEX-JOGMEC joint study “Chicontepec Project” aims to design an optimized development plan based on the results of geostatistical reservoir characterization for low-productivity turbidite sandstone reservoirs in the Chicontepec Basin, Mexico. As interim results of the Phase-II study, the study focuses on (i) the diagenetic reservoir distribution analysis and (ii) cross validation of different geostatistical reservoir modeling methods.

(a) Diagenetic effects are one of important factors controlling reservoir heterogeneity in the Chicontepec reservoirs. The results of diagenesis mapping show that the lower reservoirs are intensely cemented, whereas the upper tends to be dissolved.
(b) Different geostatistical modeling methods have been used for Agua Fria and Tajin fields in Phase−I study. For comparison purposes, cross validation is used as a means of establishing the better geostatistical modeling method. The results show the performance of the Tajin method is generally better and fairer than that of the Agua Fria method.