Research On Discriminant Method Of Dominant Seepage Channel Of Condensate Gas Reservoirs With Edge And Bottom Water

Condensate gas field has a special important position in the world. With the deep development of exploration degree, more and more condensate gas fields have been found. The development and study of the condensate gas field is increasingly important. Since the gas condensate field in our country has been water breakthrough in the development process, leading to edge water onrush and bottom water coning, then it flowed into the wellbore, and gas wells produced water and effusion. The result is gas production greatly reduced and even not produced any more. It has a serious influence to normal production and life of the gas well. So it is difficult to develop the condensate gas reservoirs with edge and bottom water. How to improve the development efficiency of gas condensate fields, especially the influence about the formation of water dominant channel. It has the important and realistic significance to research.Tahe condensate gas field have block, active edge-bottom water and depletion exploitation characteristics. In recent years, with the continuous development of the condensate gas reservoir in tahe oilfield, the reservoir pressure gradually decreases, especially the high gas production rate result in the rapid decline of the gas reservoir pressure and the gas well productivity drastically reduced and precipitation of condensate. The reserves producing degree of condensate gas reservoir in tahe oilfield is low, the reservoir vertical developed a large number of low-permeability layer. It also has strong heterogeneity, and gas wells produced large amounts of formation water with the gas reservoir pressure drops until the gas wells stopped producing. At present, edge-bottom water leads to low recovery degree of the condensate gas reservoir in tahe oilfield. It is development effect is not ideal.In this paper, two main condensate gas reservoirs (S3-1, AT11) in tahe oilfield are studied. On the basis of extensive research and the successful experience of the previous are summed up, through the use of the gas reservoir dynamic analysis method, I analyzed the gas reservoir dynamic and static data, selected the representative parameters and judged the advantage seepage channel. Then through expert systems of fuzzy discriminate method, which combined with analytic hierarchy process for qualitative identification about the advantages seepage passage of the two condensate gas reservoirs. And the advantage seepage paths of the two blocks are described by the connectivity between the wells. On the basis of the above research, this paper got the following results and understanding:1. The S3-1block of condensate gas reservoir in tahe oilfield block composite water cut reached44.67%, and it is relatively high. Water cut rising rate is9.57%, the water cut raised quickly. The gas extraction rate is2.75%. The condensate rate is3.2%and the speed is slow by June of2012. The block has put into production for five and a half years. Due to the longitudinal development of low permeability reservoir layers and strong heterogeneity, which have a big influence to the oil and gas flow, the oil and gas vertical migration ability is greatly reduced. Calculation about natural gas recovery level is20.99%, which is low. Block reserves producing degree is low, the deep reservoir exploration has certain potential. Part of the gas wells capacity is decreasing quickly due to formation water breakthrough. Bottom water along the permeable zone onrush, and then formed storm flooding. After the gas well saw water in January2009, the S3-1block daily production capacity has dropped by nearly50t, production declines about35.71%. Because of the small body of water, and the gas wells do not take timely and effect measures to water shutoff, the water does not play a supplementary role in the formation energy.By analyzing the area of reservoir geological features (Depositional environment, Lithological characteristics, Pore structure, Heterogeneity), I judged the district has formed geological factors of the dominant seepage channel, and its advantage seepage channel formation mechanism has been studied. Later, based on static parameters of the geological, production dynamics and analysis of test data, through the base parameter optimization and the calculated key parameters, I integrated use of fluid mechanics and fluid mechanics theory. Through fuzzy mathematics analysis method combined with analytic hierarchy process advantage seepage channel for the qualitative judgment. Advantage seepage paths in the area are divided into three types:immature advantage seepage paths, weak the developmental advantages seepage channel, the developmental advantages seepage channel. At last, by well connectivity judgment, combined with the early results of the advantages seepage channel, I think that the S3-2H and S3-6H has the advantages seepage paths.2. The AT11block of condensate gas reservoir in tahe oilfield composite water cut reached13.14%. Water cut rising rate is22.64%, the water cut raised quickly. The gas extraction rate is2.12%. The condensate rate is3.2%and the speed is slow by June of2012. The block has put into production for four years. Calculation about natural gas recovery level is20.99%, which is low. The main problems include:Affected by bottom water coning, some of the gas wells are shut down due to effusion minting. There are a total6wells are discontinued, among these five wells moisture content greater than75%. Normal production AT11, AT11-1, AT11-3wells in the production process are only sporadically see water, mainly governed by the mezzanine impact, and they have low moisture content. Because the high water content, oil pressure drops rapidly, part of the wells has low production, even no production. Also the reservoir is single, no other layers can tap the potential. And because of the early production measures as irrational, it is difficult for discontinued wells to take effective measures to re-production.The same analysis method with S3-1block, I analysis the reservoir geological features, and judged the district has formed geological factors of the dominant seepage channel. Its advantage seepage channel formation mechanism also has been studied. Later, through fuzzy mathematics analysis method combined with analytic hierarchy process advantage seepage channel for the qualitative judgment. Advantage seepage paths in the area are divided into two types:weak the developmental advantages seepage channel, the developmental advantages seepage channel. At last, by well connectivity judgment, combined with the early results of the advantages seepage channel, I think that the AT11-4and AT11-6H has the advantages seepage channel.