The popularization and application of compound salt drilling fluid has become the new normal of drilling in Shengli Oilfield. In view of the problems existing in the exploration period, the construction plan and supporting measures are gradually improved to form a mature construction technology. Compared with the conventional polymer drilling fluid, the improved compound salt drilling fluid not only reduces the hole enlargement rate by 70.61%, improves the ROP by 30.59% and achieves 100% success rate of one-time logging, but also solves the reaming problem in the upper Ng Formation caused by sticking and wellbore stability problem in the lower Es Formation, which is worthy of popularization and application.
Aiming at the problem of drill pipe washout in the SHYB583 well in Saudi Arabia, the failure mechanism of drill rod is studied by analyzing the physical and chemical properties of thickened transition zone, stress analysis of transition zone under the combined action of tension, bending and torsion, flow field characteristics of inner channel, dynamic characteristics and fatigue analysis of drill string under the condition of actual well trajectory. The results show that the thickness of some parts of the coating of the failed drill pipe sample does not meet the requirements of SY/T 0544-2010 technical conditions for internal coating of petroleum drill pipe (seriously thin), and the drill pipe material contains high index nitride, which reduces the impact toughness of the drill pipe, thus reducing the fatigue life of the drill pipe. Under the combined load, the transition section of the drill pipe has a high stress level, and there is a significant eddy current near the transition zone, and the total pressure of the drill pipe caused by the internal flow field is large. The drill string does not produce more severe whirl, and the amplitude of axial vibration and transverse vibration is small, but the vibration frequency of bending stress is twice of the rotation frequency of the drill string. The large dogleg of the failed drill string increases the bending stress, which makes the drill string more prone to fatigue failure.
Microorganisms as the biotic factor are capable to participate in processes leaching of a rock of an oil layer directly, and also by secretion of various agents leaching -gases, acids, spirits, slime, etc. The basic mechanism leaching of a rock is formation of chelates by microbial agents with minerals of a rock. The order of carrying out of elements from minerals of rock of a class alumosilicates basically is defined by structure and property of the mineral. The elements making cristallic a lattice of a mineral will least intensively be mobilized; isomorphically replaced or exchange ions which are taking place on peripheral sites of mineral particles will most intensively be mobilized . Knowledge of physical and chemical features of a collector - the nature and a cementing mineral of a rock, his maintenance in a rock, type of cement (bazalic or pore type etc.) and other parameters, in the certain degree allow to predict probability of shaking of structure of a rock of a collector and speed of his destruction during technological influence. At selective leaching minerals of collector properties of rock can be modified both aside deterioration, and aside improvements of filtrational properties of pore spaces of a reservoir. Deterioration of collector properties can be shown, for example, in display sand recovery to wells-bottom (most likely in the first in sandy collectors with the small maintenance of a cementing material of montmorillonite type). In collectors with the high maintenance of a cementing material (bazalic or pore type of cement) leaching can promote substantial improvement of collector properties in connection with increase of permeability due to formation of secondary porosity.
Coalbed methane (CBM) is a kind of natural gas which is stored in the micropores and fractures of the “coal seam” and has not been transported out of the source rock. Conventional logging technology plays an important role in coalbed methane exploration and development. By analyzing the response characteristics of conventional logging of coalbed methane, coal bearing strata are accurately determined. Two methods of statistical model and volume model are established to analyze and calculate industrial components. Based on the study of adsorption isotherm and correlation between logging parameters and coal core gas content, the calculation method of coal seam gas content is determined In practices, the calculation accuracy of industrial components and gas content of coal seam has been significantly improved. Abstract: coalbed methane (CBM) is a kind of natural gas which is stored in the micropores and fractures of “coal seam” and has not been transported out of the source rock. Conventional logging technology plays an important role in coalbed methane exploration and development. By analyzing the response characteristics of conventional logging of coalbed methane, coal bearing strata are accurately determined. Two methods of statistical model and volume model are established to analyze and calculate industrial components. Based on the study of adsorption isotherm and correlation between logging parameters and coal core gas content, the calculation method of coal seam gas content is determined In practice, the calculation accuracy of industrial components and gas content of coal seam has been significantly improved.
Offshore Testing is a world-wide difficult problem with high danger and high risk. Many technical problems in the field of national offshore oil production are still pending. The safety of testing string is affected by multiple complex factors, and it is a complicated nonlinear problem with marked deformation and indeterminacy. The traditional risk assessment methods no longer meet the need for risk assessment of testing string. This paper adopts fuzzy comprehensive evaluation, which is based on the AHP (analytic hierarchy process) to assess the security of strings of deepwater gas well. First of all, it makes model, analyses the factors of the risk, divides the hierarchy and adopts AHP (analytic hierarchy process) to determine the weight of each factor. Secondly it seeks the experts’ reviews to establish the aggregation of comments, researches the effect of each assessment factors, makes fuzzy assessment of each factor, and makes fuzzy information of many describing different aspects of the object which has different dimensions quantification. Lastly, it makes fuzzy comprehensive evaluation in order to make sure the risk assessment level of testing string and achieve quantitative analysis of the risk factors that effect testing string and assess the safety of testing string scientifically.
