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Jiuquan, China

Zhao J.-Z.,Southwest Petroleum University | Zhou L.-L.,Southwest Petroleum University | Ma J.-J.,Yumen Oilfield Company | Li Y.-M.,Southwest Petroleum University
Natural Gas Geoscience | Year: 2015

Hydraulic fracturing is an essential technology to stimulate shale reservoirs, and accurate prediction of fractured shale gas well productivity is the basic for the efficient development of shale gas reservoir. This paper establishes a gas-water two-phase percolation mathematical model under the condition of desorption and diffusion by means of numerical simulation and calculation method. And the numerical model is given in this paper. By means of the simulator for post-fracturing performance of the shale gas reservoir is developed, and quantitative analysis of the influence of fracture parameters, physical parameters and desorption diffusion parameters to fractured shale gas well production is investigated. The research results show that hydraulic fracturing improves single well production, and it's an effective measure to develop shale gas. Therefore the induced hydraulic fracture conductivity and natural fracture permeability are the main influence factors on shale gas production, and the higher the induced fracture conductivity and natural fracture permeability, the higher the gas and water production rate. Relatively speaking, the matrix permeability and diffusion coefficients have less effect on production. ©, 2015, Science Press. All right reserved. Source


Qu W.,Xian Shiyou University | Sun X.,Xian Shiyou University | Gou J.,Petrochina | Tang F.,Yumen Oilfield Company
Materials Science Forum | Year: 2016

Aimed at the serious problem of N80 tubing failure in the drainage of CBM (Coal bed methane) well, it can define the failure into two types: eccentric failure wear and the corrosion failure, through analyzing the well space structure, the stress and the chemical reaction on the tube in the coal bed water. The main reason is well deviation, instability of rod string and rod vibration. It makes sucker rod contacts with the N80 tube, when the sucker rod is up and down, the friction exists between the sucker rod and the tube, which leads to the tube wear out. Corrosion failure may happened in the condition that there are some acid anions in the coal seam water, such as HS-, S2-, Cl-, HCO3 -, SO4 2-, CO3 2-, etc. These ions react with N80 tubing that corrodes and destroys the N80 tube. In this paper, we suggest to replace the N80 tube with the UHMWPE (ultra-high molecular weight polyethylene) liner tube. This is capable to reduce the wear and corrosion rate effectively. The field tests show that it is still useful over 600 days, which means that the serving life of UHMWPE liner tube can be increased over 50 percent than others. Therefore, it has a significant meaning to popularize UHMWPE liner tube in the CBM well. © 2016 Trans Tech Publications, Switzerland. Source


Chen Z.-X.,China University of Petroleum - Beijing | Chen Z.-X.,China National Petroleum Corporation | Fan H.-H.,China University of Petroleum - Beijing | Shi D.-H.,Yumen Oilfield Company | And 3 more authors.
Oilfield Chemistry | Year: 2013

Through the development of X-diffraction, coefficient of rolling recovery and expansion laboratory experiments, the physical and chemical performance distribution rule of the formation clay mineral in Baka area was summarized. According to characteristics of formation lithological and technical difficulties of the drilling fluid used in Baka area, combined with the existing several different drilling fluid systems, including sulphonated polymer mud, polyether glycol drilling fluid, and amino poly alcohol drilling fluid, the conventional performance, inhibition performance and plugging and anti -sloughing ability were investigated and the best drilling fluid was carried out in t Ke21-ping 1 well. The experimental results showed that the content of coal and clay minerals were higher, thereinto, the clay minerals were mainly illite and smectite mixed layer, which meant that the drilling fluid in coal seam drilling hole should have strong inhibitory, in the lower should have anti-sloughing ability. The recipe of the optimal drilling fluid system with the strongest inhibitory and plugging and anti-sloughing ability, an amino poly alcohol drilling fluid, was as follows: (4%-5%) bentonite + 0.5% amino poly alcohol AP-1 + 0.5% aluminum polymer anti-sloughing agent DLP-1 + (0.8%-1%) Hydrolyzed polyacrylonitrile sodium NaHPAN + 0.5% NaOH + (0.3%-0.5%) carboxymethyl cellulose CMC + (3%-4%)cationic emulsified asphalt + 3% sulfomethylation phenolic resin SMP-1 +(3%-5%)sulfomethylation phenolic resin SMP-2+3% lignite resin SPNH +2% non-invaded protection agents BST-2+3% sulfonated tannins SMT+(2%-4%)sulfonated humic acid chromium PSC. The API filtration of the optimal drilling fluid was 4.2 mL, and the high temperature and high pressure filtration was 12 mL, which could inhibit shale hydration swelling effectively, exhibiting the excellent plugging and anti - sloughing ability. Field test results of Ke21-ping 1 well showed that in the coal seam section drilling process the underground complicated accidents had not occurred to, and the penetration of many sets of coal seam and coal-bearing stratum was achieved successfully. At the same time, it also ensured the stability of directional drilling of borehole wall, and made the drilling cycle significantly shorten and the performance of drilling fluid maintenance more easily. The operation was simple and could fulfill the safety drilling requirements of coal seam hole. Source


Ran B.,Chengdu University of Technology | Li Y.L.,China University of Geosciences | Zhu L.D.,Chengdu University of Technology | Zheng R.C.,Chengdu University of Technology | And 2 more authors.
Acta Petrologica Sinica | Year: 2013

The Jiuxi basin, bounded by the Altyn Tagh fault and northern Qilian fault located in the northern margin of the Tibetan Plateau, is the perfect area to study the Early Cenozoic tectonic action, because the tectonic events of the two faults were recorded in the Late Eocene sediments. In this paper, an integrated research of sedimentary facies, heavy minerals, and paleocurrents on eleven sedimentary sections from the Jiuxi basin provides a detailed record of the early tectonic evolution of the northern margin of the Tibetan Plateau since the Late Eocene. Then these data indicate the sedimentary frame of the earliest sediments records, the Huoshaogou Formation, in the Jiuxi basin was constrained by the left-slip motion along the northern part of the Altyn Tagh fault. However, the Altyn Tagh fault could not extend beyond the Tibetan Plateau within the Alxa block because of the rigid nature of the Alxa block. Hence this strong crustal extrusion from the Altyn Tagh fault had to southwardly transform to the northern Qilian fault to south which resulted Early Cenozoic thrusting of the northern Qilian fault while the foreland basin stage of the Jiuxi basin had been formed. Source


Liu Y.,Southwest Petroleum University | Zhang F.,Southwest Petroleum University | Wang X.-Z.,Southwest Petroleum University | Bie Q.,Petrochina | And 2 more authors.
Geology in China | Year: 2010

The main Carboniferous reservoir rocks in Kaijiang area are granular and rubble dolomites. The reservoirs are characterized by low porosity and permeability, low water saturation, and the mesoporous and small throat system. Reservoir performance is mainly controlled by fissures, which were mainly formed in Himalayan period and have become the main channels for Carboniferous natural gas, with most of the structural fissures not filled or half-filled. The favorable reservoir diagenetic event was dolomitization. Karst slope and palaeostructure slope constituted the Indosinian paleouplift slope or the palaeostructure height in subsequent geological history, and the reservoir space was further dissolved by acidic water in the formation under the later burial action. This area has always been in the well-developed secondary dissolution pore zone and the favorable zone for oil and gas migration and aggregation. Therefore, the Kaijiang Carboniferous reservoir favorable area is mainly distributed in the paleokarst slope which is developed in the erosional Carboniferous remnants around the Kaijiang-Jiangping zone. Source

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