Knowing the temperature distribution in gas well is of great importance to gas well design and dynamic analysis; accurate prediction of wellbore temperature distribution can improve the accuracy of wellbore pressure prediction. Based on energy conservation law, a mathematical model for calculating wellboretemperature distribution in a gas well has been developed. This model assumes steady-state heat transfer inside the wellbore and transient heat transfer in the adjacent formation. Data from the literature are used to testify the validity of the model. Results indicate that the temperature distribution predicted by the model agrees well with the measured data.
According to the technical procedures and the characteristics of well -testing for a swabbing well and the formation pressure distribution of last swabbing, we developed a new mathematics model of well-testing analysis for the next step swabbing, and obtained the theoretical solution for this new model in Laplace space. Application results in Changqing oil field showed that this new model can describe the characteristics of transient drops of the well pressure in swabbing producer and the changes of the non- regularly characteristics of the well pressure during the swabbing procedures. The ratio of the well -testing data is used and the reliability of the analysis results can be also increased. The well pressure of a swabbing producing well can be calculated with this new model as well.
Comprehensively integrated well testing interpretation model and the automatic recognization of the model have being a hard point for the study on the area. In order to solve the problems of curve pattern recognization and model diagnosing inference, a new method of well testing model recognization is presented in the paper based on syntactic pattern recognization. The complicated process recognizing pattern is simplified into characteristic extraction, shape tracing and model inference. A set of highly effective interpretation software integrating interpretation models is developed by well testing analyses and nonlinear optimization technology.
Based on the analysis of conventional rock wettability evaluation methods, a sand-pack flooding experiment procedure for the research of effect of partially hydrolyzed polyacrylamide on sand partial wettability has been established. Use this procedure, the effect of polymer solution on sand grain wettability is measured under different TDS and polymer concentrations. The results show that the presence of adsorbed polymer always induces an increase in the water irreducible saturation and decrease the residual oil saturation. It makes the sand grain become more water-wettability. The enhancement of the water-wettability of the sand grain affected by polymer concentration and TDS. It increases with polymer concentration and decreases with TDS in the interesting ranges.
Since the acoustic velocity is an acoustic index that can reflect the comprehension physical properties of formation rock in fairly good condition, it is widely used in all the technical fields of oil exploration and development. In this paper, the methods of the rock acoustic velocities and the uniaxial compression strength measurement in the laboratory are introduced briefly. And the studies of the correlation the acoustic velocity with uniaxial compression strength of rocks and the surface acoustic velocity with logging acoustic velocity by regression analysis, their data analysis procedure and their qualitative-quantitative conclusions are discussed deeply. Based on comprehensive analysis, the paper describes the mathematical models and their prediction profiles that are established for field to predict uniaxial compression strength of rocks by means of acoustic velocities from logging. As a content of an experimental study, the application prospect of this research result is also presented in the conclusions.
In order to explore old reservoir potential, 3-D seismic data and drilling data are integrated and used in reservoir areas are determined: (1) the mini-structures around faults; (2)the structure formed by sealing of fault plane; (3) the blind areas surrounded by faults and (4) the lower part blind areas located not on main stream lines. The potential exploring illustrates that 3-D seismic data has incomparable advantage over 2 -D ones, specially, exploring old reservoir potential will be effectively guided by tight combination of 3-D seismic data and drilling data so as to determine well location.
The natural gas resources in the remote magical areas in oil/gas fields include let-out gas (mainly associated gas) and low pressure well gas, which have not being utilized for a long time because of low yield, no local users and far away from transportation pipeline. The resource is not only considerably wasted, but environment is servile polluted. After demonstrating purification and integrated utilization technology of natural gas development of remote marginal areas in oil/gas fields both at home and away, it is recognized that reasonable purification and utilization technology should be put into use according to gas quality, quantity and the demand of market. Finally, integrated utilization of gas resource in the remote regional areas in TuHa oilfield is studied.
Dongyun formation, Oligocene series in Dalujia area is on of the main production formation of Linpan oil field deposition system is mainly made up by the delta from part, and its sand body genetic type includes river-ountain, sublacustrine distributary channel, sublacustrine levee, sublacustrine crevassesplay, distal bar, sheet coveting in delta front subfacies, which have been identified through comprehensive use of core, logging and well log data. Vertically, all these microfacies can be induced into three typical depositional sequences; uniform, decreasing and increasing upward respectively. In addition, all these microfacies identified in the area are the result of multisuperstition in the geologic time. And the interfaces are not always the interfaces of single sand beds. Through all studies inthis area and by the analysis of the deposition source from the west-north direction, the driving way of river, and the locate form extending to east-south or south, the data in this area is determined to be river-controlling type. Finally, a 3-D depositional faces model of this area has been induced, and in this model sublacustrine distributary channel and river-mouth barare in the center and the other microfacies are around them.
AbstractIn order to evaluate the oil and gas resources of the structure from Jurassic to Silurian system in Yingmai structure No.2-3 in Tarim Basin, basic electric properties of all strata from Jurassic to Silurian system in the structures are investigated. Core analysis and paleocurrent of important in the wells both in and around the structures are investigation, shows that Jurassic strata in Yingmai structure No.2-3 rise up gradually from northwest reservoir improved from northern west to southern east, and the direction of deposit source accorded with that of paleocurrent. Vertically, properties of formation on the bottom is stronger than that on middle and top. The oil and gas display in Yingmai well 3 is better than n other wells. Therefore, new oil and gas display is to be found from the apex area, which is the southern part of Yingmai well 3.
Based on the extensive surface natural asphalt, oil and gas seepage hydro-chemical property and asphalt evolution stage, integrated with regional tectonic, thermal degradation, preservation condition and the correlation of known oil and gas field, it is pointed out the preservation and potential structure study should be done on the fault-depression at Mesozoic and Paleozoic outcrop areas. It is in the area with good preservation and thermal action is procreating that fault trap and organic reef gas pool will be found. It is not favorable area to find gas field in the area, which the natural asphalt commonly occurs and oil and gas seepage and extensional fracture are developed.
Trap evaluation is the core of oil/gas resource evaluation. But some qualitative factors make the conventional evaluation methods not convenient during the work. For example, it can only be given a dim concept about whether or not a trap contains oil- gas. Comprehensive evaluation method of blurred mathematics can deal with the “be this and that” with mathematical method. Therefore, it can be evaluated quantitatively. It is the advantage of comprehensive evaluation method of blurred mathematics in trap evaluation.
A hybrid fast genetic algorithm (H2O) is proposed on the basis of various characteristics of nature evolution. This algorithm is combined with niche technician, a variety of crossover schemes, multi-populations and catastrophism phenomenons. Last sense, it can efficiently eliminate premature convergence of GA on the nonlinear multi-parameter optimization problem. Through testing seism wave impedance inversion, the result is obviously improved compared with the convention genetic algorithm in the convergence ability and computation efficiency.
According to the comparison of the VSP-log shooting and receiving conditions with the conventional seismic exploration, this paper discussed the accuracy of the VSP-log and the conventional seismic average velocity and the reasons which conventional seismic average velocity accuracy is lower than that of the VSP-log average velocity. The author emphasizes that it is important to restrain and correct the conventional seismic average velocity using the VSP-log average so that it provides good velocity data for the high accurate structure maps compilation used in oil-gas exploration.
Shale formation is different from “inactive” rocks when contacting with water-based drilling fluid, rock strength and the internal stress around borehole in the hale formation will change with mud properties and time in which shale formation had been opened. Finally stability will be decreased. The effects of hydration on stresses distributions, caving pressure and fracture pressure of shale formation around borehole had been studied quantitatively. The results have illustrated that shale hydration will decrease the fracture pressure, and increase caving pressure.
Aimed at low pressure and high porous formation in the deep wells in Southern margin of Jungor Basin, Xinjiang, influence of various factors on differential sticking is analyzed. Two testing methods to evaluate differential sticking tendency are recommended for Xinjiang oil field. According to parts of laboratory testing results and the characteristic of deep well drilling fluids, the technological sticking tendency is established.
Drill-string vibration system while is very complicated dynamic system, which has uncertain boundary conditions and randomness. Based on random signal theory, in order to quantitatively research drilling string by vibration measurement method, the article sketches out a new method——the identification of drill——string system using the cross correlation function. Using input signal, and output signal, the impulse response of drill-string is obtained. Some problems of drill engineering (critical rotation speed of frill-string, drill-string resonances, interaction between the drill string and the borehole wall and lithology of formation driied )are discussed.
The structure characteristic and operation mechanism of disc bit is briefly introduced in the paper, and the experimental data is analysis and processed aimed at the scraping correlation experiment between disc bit with 9 different structural parameters of disc cutting teeth and conventional insert bit with gourd -shape and wedge-shape teeth operating on the sandstone from Chongqing Member. The scraping force is obtained which is required to scrap unit volume rock, as well as maxim value, minimum valued average value of scraping force obtained during the process of scraping by different teeth, and the scraping effect by different structural teeth in scraping the sandstone from Chongqing member is gained, which provides experimental data for fourthly developing the disc bit suitable to midi-hard adsoft formation and being of highly integrated property.
Under load stresses and corrosion environment with high temperature and pressure , drill pipes occur corrosion fatigue crack easily in drilling mud. A simulated testing apparatus was used to study the crackprocessof drillpipes so as to find an efficient protection method in laboratory. Corrosion fatigue behaviors of steel 45 are studied using self - made rotary type bending corrosion fatigue testing apparatus in salt drilling fluids, as well the effect of some mechanics factors and medium factors, such as cyclic stress, load frequency, temperature , on the corrosion fatigue crack of steel 45 . Results showed that corrosion fatigue crack of steel45 was depended on the corrosion rate of steel 45,especially the extent of pitting corrosion. The corrosion fatigue life of steel 45 increased with the increase of load frequency.While temperature reached 45 C or so , the corrosion fatigue crack of steel 45 was the most quickly.
