Keywords: mechanical sand control and chemical sand control in oil wells
China Library Classification Number: TE358 Document Identification Number: A Document Number:1672-3791(2012) 05 (a)-0087-02.
1 TUHA oil region
1. 1 An Oilfield Ⅰ
Reservoir characteristics of 1. 1. 1
The heavy oil reservoir in an oilfield is coarse sandstone and the sedimentary type is river delta facies. The reservoir has loose cementation, low diagenesis, poor consolidation performance and weak cementation degree, mainly argillaceous cementation, and is a strong water-sensitive reservoir. The argillaceous content is 6.53%. Carbonate cement is 0.99%. The cementation degree of reservoirs in eastern Henan block is weak, and some intervals are loose. The cementation type is mainly argillaceous cementation, and the total cement content is 6.8%, including argillaceous content of 5.58% and carbonate cementation content of 1.22%. Kaolinite and chlorite are the main argillaceous cements, with relative contents of 42. 1% and 25.6% respectively. The content of Iraq/Mongolia mixed layer is 20.3%. It belongs to a reservoir with high porosity and medium-high permeability.
1. 1.2 sand production
Since it was put into production, 24 wells have produced serious sand. According to the sampling analysis of two wells, the median grain size is 0. 18 mm ~ 0. 19 mm, which belongs to medium-coarse sandstone. During pump inspection, it was found that there was a large amount of sediment on the inner wall of tubing hanger, which led to pump sticking.
1.2 An Oilfield Ⅱ
Reservoir characteristics 1. 2 1
The sandstone of reservoir ⅱ in An Oilfield is dominated by carbonate cementation and clay cementation, and the total cement content is about 16%, which also belongs to river delta facies according to the type and content of cement. Drilling coring found that the reservoir core was loose. Logging interpretation shows that the acoustic time difference of reservoir is 365,438+02 ~ 350 us/m, and the possibility of sand production in reservoir is analyzed theoretically within the critical acoustic time difference of 295 ~ 395 us/m.
1.2.2 Sand production
Sand production is serious in an oilfield, especially in wells 6- 1 and 6-2.
According to the analysis of sand particles, the median particle size of 6- 1 well in an oilfield is 0.08 mm ~ 0.09 mm, which belongs to fine sandstone.
2 sand control technology application
According to the principle of early sand control and combined with the present situation, mechanical sand control and chemical sand control are mainly selected at present.
2. 1 mechanical sand control technology
Mechanical sand control can be divided into two types: hanging sand control pipe in pipe and metal sintered sand control screen. Their construction steps and sand control mechanism are basically the same, and they have been well applied in oil fields.
2. 1. 1 Sand Control Technology of Metal Sintered Oil Sand Separation Screen
The sand control pipe is made of oilstone with very high particle size and surface smoothness, which is sintered at high temperature to form a uniform fine mesh structure. The micropores in the structure are interconnected, and the liquid can freely enter and exit, which has the advantages of high permeability, uniform pores, good sand control effect and corrosion resistance. Because the oilstone itself has high smoothness and hydrophilic and oleophobic properties, it can prevent the tiny pores from being blocked by heavy oil and dead oil, and prolong the service life. Mainly used in the following four aspects.
(1) Sand control of oil, gas and water wells; (2) Suspend (sand anchor) under the pump to prevent sand; (3) Sand control of sand production layer in perforated interval; (4) Sand control for oil and gas wells with deviation less than 40.
2. 1.2 TBS integrated metal fiber sintered sand control pipe sand control technology
Metal fiber sintered sand control pipe is based on high-quality steel pipe, perforated according to certain rules, and sintered with metal fiber on the base pipe at high temperature and high pressure to form a three-dimensional mesh sand filter shield. Metal fiber can make crude oil and fine sand less than 0.07 mm pass through and be taken out of the wellbore with the oil flow, while the sand with larger particle size is blocked outside the screen, forming a natural sand barrier to achieve the purpose of sand control.
For heavy oil wells with serious sand production or thin oil wells with serious sand production, this technology can adopt full perforation interval sand control, that is, packer, sand control pipe and other supporting tools are combined to form a sand control string, so that the sand control pipe is aligned with the sand production horizon, and then the packer is set, and then the wellbore sand control string structure is formed. Its technical features are as follows.
(1) stainless steel metal fiber sintered sand control pipe is a single-layer pipe structure, which has the characteristics of high strength, low stiffness and uniform outer diameter. (2) The large diameter of the sand control pipe brings convenience to the later sand washing area in the screen pipe, and avoids the pipe string sticking accident when the sand control pipe with small diameter washes sand. (3) Stainless hard metal fiber wires used in sand control pipe string have different shapes and sizes. According to the sand production characteristics of specific oil reservoirs, sand control pipes with appropriate parameters can be manufactured by adjusting the shape and size of the wires, porosity and other parameters. (4) The stainless steel wire filter layer is sintered at high temperature and high pressure, so it is not affected by high temperature and high pressure of heavy oil injection wells, and it is resistant to corrosion of various downhole chemical reagents and has a long validity period. (5) Washing with a small washing pipe can remove the accumulated sand in the filter layer, so that the sand control pipe can be reused and the cost can be reduced.
Matching tools: Y453 series hanger, KYY release connector and fishing stab connector.
See the figure below for the construction process.
(1) Open the sliding sleeve of KYY dropping tool, clean the inside, replace the sealing ring, close the two mounting pins of the sliding sleeve and replace the four sealing rings of the center pipe. (2) Connection with hanger. Insert the center tube of the maintained dropping tool into the center of the hanger, align the keyway on the center tube with the pin hole of the hanger, tighten six pins, and adjust the locking sliding sleeve to minimize the gap. Only after detailed inspection can the tool be lowered into the well. (3) Run the sand control pipe. Before running the pipe string, processes such as sand washing, drifting, scraping and well washing must be carried out to clean up the wax deposition in the wellbore and the burr in the perforation section. Then, connect the repaired hanger, lowering joint and sand control pipe, and lower it to the required position at a limited speed. In the design, the top of the sand control pipe is located 2m ~ 3m above the perforation section, so that the sand control pipe covers the whole oil layer and the packer avoids the casing coupling. After the pipe string is in place, put the Ф ф38mm steel ball into the tubing and let it stand for 30 ~ 50 minutes. Then slowly press 12- 14MPa forward to set it, continue to press until it is successful, and lift the tubing for 3 ~ 5 m. If the setting position of the lower hanger is qualified, pull out the setting string and run it into the production string. If the sand control pipe needs to be replaced and cleaned, the fishing tool must be lowered to remove the sand control pipe.
2. 1.3 process improvement
According to the characteristics of oil field sand control, in order to simplify the sand control construction technology and reduce the number of sand card hangers, the dropping suspension mode can be changed to direct pumping connection, which saves the process of dropping and setting.
2. 1.4 tool improvement
Due to design defects, the mating joint is not easy to salvage and release after salvage. In practice, the fishing tool is improved, that is, the body is thickened on the sliding block fishing spear, and the diameter is meshed with the inner diameter of the hanger central tube, and the fishing success rate is over 98%.
2.2 Chemical (artificial borehole wall) sand control technology