Non-screen pipe compound fracturing fabric network framework gravel-filling sand prevention method

Abstract

The invention provides a compound fracturing fabric network framework gravel insertion sand prevention method which does not use a sieve tube. A prepad fluid which includes two parts is poured into a well, the first prepad fluid is a weak water solution prepared by a micro emulsion solution and formate which are disclosed in a patent document with the patent application number of 200610009675.8, the blending ratio is that each 10 tons of water is added with micro emulsion and formate, both of which take up 2 percent of water weight; the second prepad fluid is viscoelastic load fluid with the blending ratio of 40 tons of water added with guar gum which takes up 2 percent of the water weight and 20 tons of sand. The invention has the advantages that the construction is easy and convenient which is laborsaving and timesaving; at the same time, the invention is suitable for a thin oil well, a gas well, a viscous crude well and has wide adaptation range to well temperature, and can greatly improve production efficiency and the productive capacity of the oil well, guarantee the regular production of the oil and gas well and also the comprehensive economic benefit is prominent.

Description

1. Technical field [0001] The invention relates to a method for preventing sand production in oil wells or oil gas wells, especially heavy oil wells, during oil field development. 2. Background technology [0002] The currently widely used sand control technologies can be roughly divided into two categories: mechanical sand control technology and chemical sand control technology. These sand control technologies have many shortcomings in terms of practical effects. For example, mechanical sand control technology includes gravel packing sand control of wire screen, gravel packing sand control of slotted liner, sand control of sand filter pipe and so on. Their common feature is that after the wire-wound screen (or slotted liner, sand filter pipe, etc.) sand pipe, etc.) and the annular space between the casing and the part of the oil layer that is deficient around the wellbore. Their basic principle is that the filled sand layer blocks the flowback of the formation sand, and t...

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Problems solved by technology

Their common defect is that the scope of gravel packing is limited, and the slots or meshes of the screen pipes cannot be too small (if it is too small, the resistance will be large and the oil will come out less), so usually the silt and fine sand cannot be blocked at all, and Under a large production pressure difference, even the filled sand is easy to flow back out; in addition, the process is cumbersome and complicated. If you are not careful during operation, there will be more downhole falling objects, major repairs are required, and the workover is complicated and expensive. Moreover, the validity period is short, and the cost of some is relatively high.

[0003] As another example, chemical sand control technology can be roughly divided into three categories: one is resin-coated sand sand control technology, which is to coat sand with resin and dry it in the sun as a proppant, and inject it into the oil layer by fracturing for sand control. Its disadvantages are: (1) It needs a specific condition to meet the resin curing requirements, such as strict downhole temperature and pressure environmental conditions; (2) The resin is easy to chemically react with some chemicals in the sand-carrying fluid. (3) When the well is closed or opened, the cured resin is easy to break due to the change of closing pressure, which causes the resin coating effect to drop greatly; (4) After resin-coated sand treatment , although it can play the role of sand control, the permeability loss of the filling layer is very serious. Within 48 hours after construction, the well temperature of many wells can only reach 50-60 °C

The ensuing problem is: during the summer construction, the dried resin sand will re-agglomerate due to its own softening, which increases the construction difficulty; It is more complicated to carry out technical measures such as re-drilling and perforating

The second is resin sand consolidation and sand control technology, which is to inject resin into the oil layer and make the resin consolidate the sand in the oil layer to achieve the purpose of sand control. The biggest disadvantage is that the permeability of the oil layer is greatly reduced, the cost is high, and it is poisonous.

The third is artificial well wall sand control technology. There are many types of artificial well walls. For example, pre-coated gravel, resin mortar, water belt dry lime sand, cement mortar, emulsified cement, resin walnut shell, etc. are pumped to the oil layer through the pipe string. And squeeze into the cavity outside the casing to form a dense filling layer. After solidification, the excess filling in the wellbore is drilled and milled, perforated, and put into production. The biggest defect is that it will cause great damage to the oil layer and the permeability The loss is huge, the construction is cumbersome and time-consuming, and the actual effect is not very obvious

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