Discussion on wax cleaning technology and equipment for self-circulating heat washing well in oil field
Nov 16, 2018

[Abstract] In the oilfield industry center, the technology of heat washing and wax removal in low pressure and low permeability areas has caused conflicts between formation fluids due to various reasons, which makes the work cycle spread more widely, and the connection of process nodes is more difficult, especially internal water accumulation. The problem has been difficult to recover, and if the situation is very serious, it will cause serious pollution in the entire oil well. In order to cope with the above-mentioned series of hidden dangers, an oil field decided to apply the self-circulating hot-washing route for scale development, and after the heating and transformation of the oil well's individual liquid potential, it was directly poured into the oil-ring annulus to produce some self-circulation. Morphological structure; and use the hot oil heating means to achieve the motivation of comprehensive cleaning. Therefore, this paper specifically verifies the practical application results of such technical projects in specific oilfield operations, and appropriately explores the corresponding reform experience, which is a convenient door for the scientific operation of equipment and cost savings.

Foreword: The so-called hot-washing process is actually using boilers to heat the fluid material on the tanker. After that, it is injected into the well with the pump tube of the ring structure. The fluid will use this kind of environmental control conditions to enter the inside of the oil pipe and finally return. To the wellhead location. During the entire cyclic motion, the wax body in the surface of the tube wall is heated to be converted into a fluid and carried out of the wellbore. This type of wax cleaning technology is simple in design and easy to operate. However, once it is put into the oil well with low formation pressure, because the pressure and temperature control ability involved in the hot wax cleaning step is not ideal, and the reaction effect between the well fluid and the formation is sensitive, once any details are handled improperly It will cause long-term pollution of the oil layer. If the situation is aggravated, the casing will be damaged, which is not conducive to the smooth connection of the later process.

I. Discussion on the working mechanism of self-circulating well washing technology

In view of the relevant details in the past traditional process environment, the relevant oilfield industry center decided to absorb the experience of foreign self-circulating wax cleaning technology to carry out scale transformation, and use the agglomeration effect of the mixture generated in the later stage of oil well heating to achieve self-circulation. The system architecture builds the goal to ensure the smooth completion of the entire hot wash work, and comprehensively restrains the crisis of the previous formation pressure bottleneck. This type of process advocates the arrangement of the details of the hot wash and wax removal work under the auxiliary range of the oil pumping machinery. Because the pumping unit continuously draws out the mixed liquid through the oil well, it is then warmed with the self-circulating well washing equipment to ensure that the modified well fluid can be fully regulated in the pre-designed annular space and transported quickly through the high-speed pipe. To the bottom of the well, the temperature of the tubing and well fluid is simultaneously raised. Because a certain heat carrier circulation structure has been formed, the heating effect of the oil pipe can be increased step by layer according to the grading standard, and the wax in the inner surface of the oil pipe and the sucker rod is rapidly dissolved, and the liquid in the well is thus subjected to a heat exchange reaction. After the overall temperature reaches a certain standard, the high melting point dirt on the inner wall of the oil pipe can be completely washed.

In this cyclic structure, especially after the inside and outside of the tubing appliance is heated, the fouling layer will slowly disintegrate and disappear until a vertical mode heat exchange system is produced, ensuring that the entire waxing operation can meet the expected planning standards. This type of well washing equipment has a large difference effect from the previous form, mainly because it realizes the liquid washing flow target inside the closed heating oil jacket. The whole process mainly uses the pumping machinery's own power as a supplementary medium, and the overall temperature effect reaches the established standard. The heating is stopped, and finally the internal heat recovery effect of the combined equipment is used to complete the subsequent heating work, so that the overall energy consumption effect will be correspondingly alleviated. The well-washing technology specifically uses data collection systems and micro-electronic processing techniques to store node data, and stabilizes the safety and environmental value of the entire system.

Second, the self-circulating well washing process, equipment application analysis

In order to optimize the design of such equipment and process techniques, the main factors affecting the wax formation of the oil well should be considered, and the full analysis details of the crude oil should be combined to effectively confirm the crude oil properties and wax characteristics. After scientific examination, it mainly presents relative density, kinematic viscosity, freezing point, wax content, colloidal asphaltene content, etc.; while waxy analysis work is carried out on the scale development of wax distribution, wax melting point and waxing temperature. Therefore, China specifically cites such process projects to implement on-site structural development and improvement in the past eight or eight years. During this period, the application scenarios of G97-6, G32-27 and other types of equipment are widely opened, and the overall application effectiveness should not be underestimated.

(1) Analysis of oil temperature phenomenon at the wellhead before and after the well washing process

In order to achieve the goal of self-circulating well washing system, the primary task is to elaborate on the temperature phenomenon, because the temperature change characteristics of the liquid entering and producing liquid will directly affect the final well washing quality throughout the cleaning process.

(II) Analysis of the comprehensive performance results before and after the application of the entire self-circulating well washing technology

Since the construction of this type of process structure has been extensively extended, all kinds of impurities related to condensation inside the oil well have been completely removed, which makes the internal circulation space of the oil pipe grow, and the average daily oil production data is increasing day by day, and the actual improvement range is as high as 15%. On the other hand, after the completion of the well washing process, the effect of the waxing effect is necessary to be alleviated, especially for the oil rod device, the actual resistance effect is relieved a lot; at the same time, the economical quantity of such hot washing engineering is far lower than the traditional process standard. It effectively restrains the breeding effect of the past secondary pollution crisis and avoids the accumulation reaction of the labor intensity of construction workers. After scientific data analysis, under the premise of specifically grasping the characteristics of oil well waxing and management platform in specific oilfields, the drilling and research laboratory actively selects the comprehensive wax cleaning process that is more in line with economic standards, which is to use the thermal energy effect to produce paraffin impurities condensed on the inner wall of the wellbore. The dissolution reaction; in addition, in order to effectively curb the energy crisis and reservoir defect expansion in the cleaning process, the field test technician decided to enhance the anti-pollution energy efficiency standard of the self-circulating wax removal system. The specific process steps are as follows: Firstly, the use of various types of anti-pollution wax cleaning equipment and column optimization structure to achieve the shortening goal of the hot wash circuit, correspondingly improve the overall heat wash efficiency; secondly, install the packer and branch pipe in the downhole position Single flow valve and other structures. In this way, the hot wash fluid can be isolated from the reservoir and the reservoir contamination signs can be completely eliminated.

Through the simultaneous detection and verification of the actual production environment and the laboratory, it is proved that such means can effectively restrain the effect of wax formation on the comprehensive production activities, and at the same time avoid the coagulation of the high-condensation oil in the tube during the period of avoiding the shutdown period and lying down. In the column, a contribution is made to restore the pace of life.

Conclusion: After comprehensive data comparison and verification, it is found that the self-circulating hot-washing well-cleaning technology and equipment and equipment have reached a harmonious handover performance standard, which can consciously resist formation pollution and damage hidden dangers, especially in the later stage of washing. Very large; the effect of the comprehensive temperature conditions is very significant, the relevant oil wells and stress conditions are reasonably reduced, the entire wax cleaning work is very thorough; in contrast, it is easier to save the amount of drugs and well washing costs.

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