| With the continuous development of global technology and industry, people growing demand for oil and other fossil energy. Old oil field after a long time mining, production and recovery factor serious decline, conventional development scheme of production has gradually cannot meet the demand of people. As oil exploration theory gradually mature, and the technology of development innovation, some low permeability, buried deep, less displacement distance reservoir of oil and gas gradually into everyone’s vision, those reservoir which applying this kind of conventional development scheme can not meet the economic exploitation are collectively referred to as "unconventional oil and gas". There are a lot of members in the unconventional oil and gas "family". The tight oil is the most successful in the "family". Its success is largely because of the western Canada sedimentary basin shale reservoir and the bakken group’s successful exploitation. The effective exploitation and utilization of unconventional oil and gas resources gradually been paid great attention in petroleum industry. Tight oil did not make people disappointed, the tight oil production is rapidly increased, its proportion in global crude oil output increase gradually. The rapidly increased of tight oil production success offset the huge demand gap caused by the increased demand for crude oil and conventional oil and gas production’s decline, showed it’s unusual exploitation value.Because of the tight oil reservoir permeability is low, poor connectivity, using conventional development method is hard to get effective production. before the well completion people usually remould the reservoir to increase the permeability and connectivity of reservoir, in order to achieve the goal of increase production. This technology is currently one of the core technology in unconventional oil and gas development "hydraulic fracturing technology". With the continuous development of exploration technology, proven reservoir exploration difficulty also will increase. The original reservoir reconstruction technology already cannot satisfy the needs of the current exploration and development. As a result, people on the basis of the original fracturing technology, developed a variety of new fracturing technology. For example, "repeated fracturing, channel fracturing, SRV fracturing", people will also combine horizontal well technology with fracturing technology, formed the widely use of horizontal multi-stage fracturing technology, effect of production increase is very obvious, played a vital role in oilfield exploitation. Although these technologies have different construction process, but its core is same, use reservoir reconstruction technology remould the reservoir around the wellbore, create artificial fracture. These fracture will serve as seepage channels for the crude oil flow from the reservoir to the wellbore, increase the permeability of reservoir and connectivity so as to realize the purpose of production increase.Fracture conductivity is one of the important indicators to evaluate the artificial fracture’s effect, therefore, analyze the influence factors of fracture conductivity, study how to increase fracture conductivity, has important practical significance on improve the effect of fracturing technology to increase production.Width and permeability of fracture is the main influence factors of fracture conductivity, width of fracture is mainly affected by the construction parameters, such as pump injection program, and the permeability is maily provided by the proppant, affected by its types, grain size and the influence of different parameters such as particle size combination. This paper took the proppant as the research object, based on the of analysis of influence factors, through two kinds of method,numerical simulation and indoor experiments, to proceed qualitative and quantitative analysis of the proppant influence, finally combining McGuire yield ratio curve to forecast yield ratio for the optimized result.First of all, in this paper, qualitative analyze the proppant which used in the practical production from strength, percentage of damage and cost, the analysis shows that quartz sand strength is low, easy to broken, but the price is relatively cheap; Ceramsite have a high strength,not easy to broken, but due to the special material and complexing production processing,its cost is expensive. If using ceramsite as fracturing proppant how to reduce the cost under the premise of a satisfactory fracture conductivity has become the key problem.After that, the article regard Chang 72 reservoir which in the Ji Yuan oil field An 83 wellblock as the research object, using the Meyer fracturing simulation software to simulaethe fracture development situation in this reservoir; Change proppant types Then observe the changes of fracture flow capacity, use this way to analysis of the factors which influence the fracture conductivity. Comparative analysis shows that simulation results are as follows:1) Different kind of proppant,it’s support high seam are equal in the fracturing process, but using ceramsite as fracture proppant, the fracture conductivity and permeability are much higher than that of quartz sand supported fracture;2) Different size proppant, fracture height, length and width are nearly same in the process of fracturing. But fracture conductivity decreased with the decrease of the particle size of;3) Combination of different particle size of proppant, fracture height, length and width are nearly same in the process of fracturing. But different combination fracture conductivity’s difference is bigger, the greater the proportion of middle size proppant the higher fracture conductivity and permeability is, the proportion in the proppant for 1:3:1, its highest fracture conductivity and fracture permeability.At last, use laboratory experiments on the quantitative analysis of the factors which influence the fracture conductivity. In this paper, through a series of indoor experiments to analysis effect about different parameters on the fracture conductivity offered by proppant:1) quartz sand, ceramsite proppant fracture conductivity contrast experimentThis experiment using 40/60 mesh quartz sand and ceramsite, under the same closure pressure respectively. Experiment obtains that fracture which use quartz sand proppant, it’s conductivity is better than the fracture which use ceramsite proppant’s. After closure pressure exceed 20 MPa, quartz sand support fracture’s conductivity fell sharply, but ues ceramsite proppant is slow.2) strength of proppant---fracture conductivity experimentThis experiment selected three kinds of different intensity, same size proppant to experiment respectively. Experiment obtains that the higher the proppant strength, the higher initiation fracture conductivity is; And as the closure pressure rising, it’s conductivity decline slow.3) proppant thickness---fracture conductivity experimentThis study selected 10/20 mesh ceramsite proppant as the research object, use 7.5kg/m2、10 kg/m2、15 kg/m2 three concentration to experiment respectively. Contrast experiment data, the proppant which concentration is 15 kg/m2 its conductivity is the highest in different closure pressure.4) single size proppant fracture conductivity experimentThis experiment selected 10/20mesh,20/40mesh,40/60mesh, four kinds of size range of ceramsite proppant as the research object. The experiment shows that the fracture conductivity of 10/20 mesh ceramic proppant is the highest in different closure pressures. When closure pressure is over 30MPa, the bracing fracture conductivity decreases quickly. When closure pressure reaches 70MPa, the fracture conductivity of several diameter proppants are very similar.5)multi size proppant combination fracture conductivity experimentThis study choose 10/20mesh,20/40mesh,40/60mesh, 100mesh, four different diameter ceramsite proppant as the research object. Experiment obtains that use 10/20mesh,20/40mesh,40/60mesh,three kinds of proppant in 1:3:1 ratio place in the fracture sequencely can get the highest fracture conductivity, and the fracture conductivity drop slowly when the closure pressure constant rise.This paper mkes a detailed understanding on mainstream reservoir reconstruction technology nowadays. Experiment obtains that use 20/40mesh,10/20mesh, 40/60mesh,three kinds of proppant in 1:3:1 ratio place in the fracture sequencely can get the highest fracture conductivity. Use 20/40 mesh ceramsite fracture proppant’s conductivity as the foundation. It can obtaine the change percentage of fracture conductivity which ues imparity proppants in different closure pressures by comparing the experiment results, which makes a foundation on the accurate control of fracture conductivity in the future. |
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