Research On Staged Fracturing Strings With Supporting Tools Of Casing Completion Horizontal Well

Oil and gas exploration and development in China presents the situation of the new reservoir type more and more complex, the old oil field development is getting more and more difficult. How to improve the development benefit of the oilfield, the greatest degree of enhanced oil recovery has become the common goal of petroleum industry.In recent years, the domestic crude oil reserves of70%belongs to low permeability reservoir, mining, oil well production dynamic exhibit peculiarities. Effective use of reserves, increase single well production is the urgent of low permeable oilfield development. Horizontal wells of reservoirs of thin reservoir, low permeability, small reserves of heavy oil reservoir, the marginal oil and gas reservoirs is one of the most effective means. It has been widely used in block, block, edge and bottom water, heavy oil, low permeability, special lithology reservoir. Especially, it played an important role in the development of complex fault block, heavy oil, low permeability and other marginal oilfield, the ratio as high as60%.China is one of countries with relatively rich CBM resources. According to a new round of national coal bed gas resources evaluation results, five coal accumulating area in china,39coal bearing basins,68coal accumulating unit of coalbed methane resources quantity is36.8×1012m3, equaling to onshore conventional natural gas resources. By the end of2012, to obtain a total of coal-bed gas geological reserves of1180×109m3, gas bearing area691km2. In2012March, the Ministry of land and resources issued the "national shale gas resource potential assessment survey and favorable zone optimization results", said the recoverable resource potential is25.1trillion cubic meters Chinese shale gas, more than USA24.4trillion cubic meters. The successful development of USA shale gas let us realize that, in the level of technology and equipment continue to progress, economic development and utilization is very low porosity can also be very low permeability oil and gas resources. There are resources of low porosity, low permeability formation, this point we have always known, but is not believed to have economic value. With the technology and equipment level of progress, especially the application of horizontal well fracturing technology, which has the economic value, can be used as resources.Horizontal well fracturing stimulation technology in foreign countries has been study from twentieth Century80,90time, first level on the oil well fracturing is generally. After2000, with the scale field application of horizontal well, the large-scale exploitation of oil and gas and shale gas, tight gas, dense oil unconventional, many developed countries started to study the horizontal well fracturing technique. After ten years of development, has now formed a relatively perfect, can adapt to different conditions of horizontal wells downhole segmentation technology of hydraulic fracturing. The horizontal well application more staged fracturing technology mainly includes the horizontal well hydraulic jet subsection fracturing, horizontal wells dual card on fracturing technology, multi section annulus fracturing technology, liquid rubber plug isolation and staged fracturing technology, mechanical bridge plug fracturing technology, isolation of limited entry fracturing technique.This paper makes the interpretation process principle of horizontal well fracturing technology widely used, comparison and analysis of the process of each technique has advantages and disadvantages as well as in the field application also shows many problems. Research on Staged fracturing strings with supporting tools of casing completion horizontal wells, which is an efficiency, simple process and low cost less stadge fracturing technology. The three key supporting tools:fracturing sphere, short-contact of casing, and material selection of ball throwing device selection.The characteristics of fracturing sphere which puts forward three basic requirements:small density, the row of liquid without drainage amount can greatly be discharged to the wellhead; high pressure resistance, sitting in the casing fracturing shorted to stand fracturing fluid on the pressure, and also to ensure the sealing. On material selection of fracturing sphere, this paper presents several options for engineering plastics, ABS (acrylonitrile butadiene styrene), PS (polystyrene), ASA (copolymer of acrylate rubber and acrylonitrile, styrene), HDPE (high density polyethylene) etc. Discuss their respective advantages and disadvantages and mechanical properties. Select the density of fracturing sphere1.4g/cm3,1.08g/cm3and0.96g/cm3indoor test. Analyzed the force in the fluid fracturing ball, mathematical expressions are given for each force. A motion equations of fracturing ball is established by using C#programme. Selection of different density, fracturing ball diameter and different volume calculation, the relation of flowback fluid volume and velocity, and according to the result of fracturing sphere density selection provides guidance.The design of the casing fracturing horizontal well fracturing string technology short circuit are introduced, and the difference of completion casing. The fracturing short materials proposed alternatives, namely, aluminum alloy and alloy steel materials. Introduced the classification, performance of two materials, processing and using, analysis and comparison of the two as the use of the process of key part. Finally chose the35CrMo as the final liner material. The perforating gun size category, and discusses the matching problem of the perforating gun and the inner sleeve, and thus put forward the feasibility of request size of casing. The ring material on the inner sleeve is introduced in detail, it points out the feasibility as fracturing ball setting tool fluorine rubber seal ring.According to the current level of domestic technology, the casing fracturing short the minimum diameter of differential6mm is relatively safe standard. For greater security, we as differential8mm, casing fracturing at the bottom of the short connecting inner diameter is76mm. So for the51/2inch completion casing, a horizontal well completion string can into the6set of casing fracturing shorted, maximum drift diameter casing fracturing short diameter is116mm, can be divided into7stadges of fracturing.