Behavior of gas kick has been discussed as a function of the expansion, void fraction, flow pattern and pressure losses in most existing two-phase simulation models. This paper describes that the behavior is determined mainly by slip velocity of gas bubbles. The slip velocity is governed by bubble diameter and fluid densities and is slowed down by crowdedness of surrounding bubbles. A new two-phase model is developed on the slip velocity model with initial diameter input and assumption of neither coalescence nor breakage of bubbles. Initial distibution of gas, temperature distribution in wellbore, compression factor and pressure losses are also described and incorporated in the model. Simulation runs are discussed and show that the model is realistic and works satisfactorily.
Heat conduction in the cuttings-water mixture beds has been analyzed using Kunii's formula. The analysis was conducted to estimate thermal conductivities of formation rocks in situ from the effective thermal conductivity of the cuttings beds which were measured at simulated geothermal conditions by a new rapid measurement method developed by the authors. As the results of numerical experiments by the analysis, it was made clear that controlling parameters for the thermal conductivity of rock martix of the cuttings estimated, λs, were the total porosity and the effective thermal conductivity of the mixture bed measured. All measurements of the effective thermal conductivity, λe, of the mixture beds of water and cuttings from SKG-11D well, Fushime geothermal field, Kagoshima pref., Japan were conducted at the natural cooling process from 200°C to room temperature as the results of the preliminary study by using fused quartz grains. The estimated values of thermal conductivity of dry cutting particles saturated with dry air, λea, of the samples from the well agreed well with the measured values of λea of the core samples from the corresponding strata within the experimental errors. The effective thermal conductivity of rocks in situ of the well at the depth from 1, 500 to 1, 900m was estimated at 3 to 4W/(m•K).
A method is presented for calculating an expornent n in the back pressure equation from wellhead production data. This method is based on the procedure developed by KATO (1987) and is expanded to the situation where turburent flow exists near wellbore. The study includes the effect of turburent flow to the estimation of the gas in-place and some sensitivities of variables to the proposed calcuation system.
A multiple regression analysis was done to obtain equations showing a screening guide for in-situ combustion projects and their performance, on the base of the results of our simulation study previously reported (ref. (1) to (4)). A stepwise method was chosen, and initial water saturation (or intial oil saturation), absolute permeability, porosity, thickness of the reservoir, residual oil saturation, oil gravity, and air injection rate were taken as explanatory variables. 4 regression equations, for combustion zone temperature (Eq. 1 in the text), recovery (Eq. 2), propagation speed of combustion zone (Eq. 3) and maximum injection pressure (Eq. 4), were obtained. Equation for combustion zone temperature may be used for screening, taking 450°C of the combustion zone temperature as a criterion. Other equations may be used for the estimation of recovery with assumption of sweep efficiency as unity, production period and injection condition at the initial stage. An explanatory example is also shown how to engineer the in-situ combustion project.
The Chengbei oil field is located on the west side of BOHAI bay, about 90km from the city of TANGGU, TIANJIN. The oil field has been producing oil at the rate of 1, 100-1, 300kl/day from 49 producers. Artificial lift was programmed from the begining of the development stage and hydraulic jet pumps and electric submersible pumps have been employed to high water cut wells since 1988. In this paper, operation history of hydraulic jet pump during March through October 1988, selection of this artificial lift and characteristic of artificial lift wells are discussed.
In recent years, use of FRP (Fiber Reinforced Plastic) sucker rod has increased in beam pumping system. FRP sucker rod has some merits, i. e. lightweight, increase of the effective plunger stroke length. In 1987, Teikoku Oil Company started the use of FRP sucker rods in Yabase oil field, Akita Prefecture, Japan. In the case of using FRP sucker rods, it is necessary to consider the characteristics of FRP sucker rods. Because the behavior of FRP sucker rods is different from that of steel sucker rods. The production rate of FRP sucker rod pumping system fluctuates on a larger scale than steel sucker rod pumping system. Sometimes the production rate becomes nearly 0. Then we introduced the sucker rod pumping diagnostics system and analized the performance of the FRP sucker rod pumping system. Finally we obtained the peculiar performance of FRP sucker rod system and the appropriate operating conditions. The content of this paper are as follows: (1) characteristics of FRP sucker rod (2) analysis of FRP sucker rod pumping system (3) design of FRP sucker rod pumping system and field data.
In the Kubiki oil field, oil is extracted by the intermittent gas lift system. Our concern is to reduce operating cost because of the present low price of oil. So as to optimize the intermittent gas lift system, the time taken to inject gas and the cycle frequency have been determined through trial and error and other means. If production volume can be predicted, operating cost can be reduced. The flowing bottom hole pressure curves were analyzed to calculate the productivity index, reservoir pressure and fall back volume. Our prediction is based on these three statistics. We used this method of statistical analysis to predict the amount of oil that was extracted from one of our wells and the prediction closely corresponded with the actual production data. Therefore our statistical method seems to be successful.
The deposits of Minami Kanto gas field is very thick and reserves amout of methane and iodine. Production wells are completed with long perforated pipes. Most of these wells are tubingless and the artificial lift method is continuous gas lift. I have developed a simulator which is formed with a three dimensional, two-phase double porosity reservoir model and a gas lift program. Using this simulator, production rates of wells can be predicted and production tests are analized exactly.
Regarding recent development in new concept and technologies concerning artificial lift and fluid flow in pipes, optimum designing has become more dfficult. Technology Research Center of JNOC has been participating in TUFFP and TUALP that are Joint Research Projects of the University of Tulsa to get useful information in dealing with problems in these subjected areas. First, this paper presents the program named “A continuous gas lift installation design simulation” and another program for estimating fluid flow behavior. Secondly, we touch on two databases which contain readily-accessible file for litertures including TUFFP and TUALP reports.