The Design And Simulation Research Of Units Pre-stressed Earth Anchor Of Cementing

At present the main method of the reservoir development is thermal mining. The main way of thermal mining is steam injection, the ground of the steam produced formation into lower viscosity of heavy oil to mining. Steam injection process of mining, cementing casing under350℃high temperature of the highest, because the casing was cement ring cementing and limits the freedom of heat bilges cold shrink, cause casing high thermal stress produced. The thermal stress is hot production Wells is one of the main reasons for casing damage. At present main ways to solve this kind of problem is the use of pre-stressed cementing technology.Pre-stressed cementing is a kind of technique which a stress is applied on the casing sting in the well before or after solidification of the cement slurry. Because of the casing was putted pre-stress and had certain elongation in advance, can reduce or offset the casing elongation which caused by thermal stress, prevent the casing damage and extend the oil Wells’life. To apply pre-stress, the bottom of casing must be fixed firmly, then lift the casing in the wellhead to make the casing string produce the elongation. The size of pre-stressed and elongation should be equal to the thermal stress and inflation elongation when heated, this is the essence of the pre-stressed cementing technology. To apply pre-stress, the bottom of casing must be fixed firmly; earth anchor is a kind of tool used to secure the bottom of casing. At the same time, the cementing length of cementing cement should be increased, Even for the whole casing pipe for cementing, enhance the cementing quality of the casing and formation. Practice has proved, pre-stressed cementing can satisfy the requirements of steam injection thermal recovery of heavy oil.The problems of the design of domestic pre-stressed earth anchor:the existing pre-stressed earth anchor used for vertical Wells and little application in the slope, look form the material haven’t see the application of anchor in the high angle wells and the horizontal Wells. If the anchor be used of the strata in low strength and the pre-stressed can’t meet the need of the heavy oil steam injection.According to The problems of the design of domestic pre-stressed earth anchor this paper puts forward the unit pre-stressed earth anchor of cementing, the earth anchor the strength of different according to stratum we can choose different level of the earth according to different strata, very good solve the problems of the anchor be used of the strata in low strength. At the same time also can be used in the high angle wells and the horizontal Wells. With the development of computer technology, the finite element analysis method in the engineering practice well applied. And the preliminary show its reliable, accurate superiority, so this paper key components of the anchor claw uplift with ANSYS LS/DYNA simulation analysis and research. In order to study different closed angle, different eat into angle affect the anchor claw eat formation, this article through the rational selection finite element units and their parameters, and the reasonable the finite element model of anchor claw into the wall of the eat simulating research.This article through the establishment3D mechanical model of the anchor claw into the wall, after briefly introduce LS/DYNA display dynamic analysis solving process, the anchor claw with different angles into the wall and the same angle different eat into the angle into the wall, the simulation of two conditions. Get:1) Eat into the wall of the anchor claw depth, the bigger the formation of the greater resistance. The smaller open angle of earth anchor the more easily to eat in the process of pulling into the wall.2) Because existence lift acceleration, the force between the anchor claw and the Wall is great in started pulling process. As the depths of the anchor claw eat into the wall increases, the equivalent stress increased.3) In a soft formation, if the rally is greater than the strata of resistance, the uplift of anchorage failure, and can’t meet the need of heat production Wells.Through310mm diameter of well in three different anchor claws before Angle of the simulation analysis get:1) As anchor claw the anterior horn decreases, the eat depth of anchor claw decreases. And have smaller resistance.2) In this simulation results, when eat into the ground the anchor claws before Angle of32°is better than others.The needs to be improved in this paper, first of all, the research of unit pre-stressed earth anchor are not quite perfect, the lack of some experimental data. Secondly, the use of ANSYS LS/DYNA do dynamics simulation may also have some limitations.1. Pre-stressed cementing earth anchor need to do hydraulic experiment, detection of uplift open, and should do experiment of anchor claw strength, inspection anchor claw strength can meet the practical needs. Only through a large number of the experimental analysis data, and compared with the theoretical calculation, make the results of more in line with the actual situation.2. Due to time reason, the examples in the anchor claw different parameters on the anchor claw into the formation of eats research are not enough. At the same time, according to different formation parameters for simulation, the different strata that the size of the force, uplift the selection of guide level.3. The rock material research needs to be further improved.4. By other software such as can be VB, JAVA developed for the application of the interface.