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Prediction of Dynamic Wellbore Pressure in Gasified Fluid drilling

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Petroleum Science 2007年第4期4卷 66-73页

作者： Wang Zhiming1,Ping Liqiu2 and Zou Ke2 (1. School of Petroleum Engineering,Petroleum University of china,beijing 102249,china) (2. institute of drilling Engineering Technology,cnpc,beijing 100097,china) Petr Univ china Sch Petr Engn Beijing 102249 Peoples R China cnpc Inst Drilling Engn Technol Beijing 100097 Peoples R China

The basis of designing gasified drilling is to understand the behavior of gas/liquid two-phase flow in the wellbore. The equations of mass and momentum conservation and equation of fluid flow in porous media were used to establish a dynamic model to predict wellbore pressure according to the study results of Ansari and Beggs-Brill on gas-liquid two-phase flow. The dynamic model was solved by the finite difference approach combined with the mechanistic steady state model. The mechanistic dynamic model was numerically implemented into a FORTRAN 90 computer program and could simulate the coupled flow of fluid in wellbore and reservoir. The dynamic model revealed the effects of wellhead back pressure and injection rate of gas/liquid on bottomhole pressure. The model was validated against full-scale experimental data,and its 5.0% of average relative error could satisfy the accuracy requirements in engineering design.

关键词： Gasified fluid drilling dynamic model pressure prediction model validation

EXPERIMENTAL STUDY OF ROCK BREAKING EFFECT OF STEEL PARTICLES

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Journal of Hydrodynamics 2011年第2期23卷 241-246页

作者： CUI Meng ZHAI Ying-hu JI Guo-dong MOE Key Laboratory of Petroleum Engineering China University of Petroleum Beijing 102249 China cnpc drilling research institute Beijing 100195 China

Particle impact drilling is an efficient drilling technology for deep-well hard formation, With this technology, the rock is cut mainly by high-speed spherical particle impact under hydraulic action. In this article, the influence of jet flow factors, hydraulic factors and abrasive factors on rock breaking is studied through indoor experiments of impact by steel particles. The results indicate that the particle water jet has an optimal standoff distance and particle concentration; the rock breaking effect declines with the increase of the confining pressure and the decrease of the pump pressure and particle diameter. This study will provide some food of thought for the development of particle impact drilling technology.

关键词： hard formation particle impact drilling water jet rock breaking effect experimental research

AN APPROACH TO CUTTINGS FLUOROLOGGING USING HEXANE AS A SUBSTITUTE

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石油勘探与开发 1997年第4期24卷 92-96页

作者： Zhao Juying(research institute of Petroleum Exploration and Devempment, cnpc, beijing, 100083)

It is discovered that carbon tetrachloride is a fluorescence quencher in crude oil detedion with cottings fluorologging. Hexane, which has many advantages as a substitute for carbon tetrachloride, is proposed. In this paper, four typical comparison results of fluorescence spectra of crude oil samples and some of field cores and cuttings are *** sensitivity of fluorescence analysis is increased by 10 to 35 times when we substitute hexane for carbon tetrachloride as the solvent of crude oil. We also find that the lighter the crude oil,the more Obvious the increase in analysis sensitivity. lt challenges the old concopt that coal-derived oil, condensate and some light oils do not emit fluorescence. The merit of hexane system in eliminating or reducing the fluorescent interference of modified asphalts in drilling fluids for cuttings fluorologging has also been discussed.

关键词： Cuttings logging Fluorescence analysis Hexane Carbon tetrachloride Crude oil (Fluorescence quench)

Mechanism and performance of a lithium chloride accelerator

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Petroleum Science 2011年第3期8卷 328-334页

作者： Wang Chengwen Wang Ruihe Cheng Rongchao Chen Erding School of Petroleum Engineering China University of Petroleum Qingdao Shandong 266555 China Department of drilling Strategy and Planning CNPC Drilling Research Institute Beijing 100195 China drilling Engineering and Technology Corp. Shengli Petroleum Administration Bureau Dongying Shandong 257064 China

To address present concerns about thickening time and high early-strength in deepwater cementing at low temperatures when using conventional accelerators, a new type of set-accelerating admixture comprising of lithium chloride, aluminium hydroxide and alkaline metal chlorides, named as LS-A, was studied in this paper. Mechanism analysis and performance tests show that the accelerator LS-A accelerated the hydration of tri- and dicalcium silicates （C3S and C2S） at low-temperatures by speeding up the breakdown of the protective hydration film and shortening the hydration induction period. Therefore, LS-A could shorten the low-temperature thickening time and the transition time of critical gel strength from 48 to 240 Pa of the Class-G cement slurry, and improve the early compressive strength of set cement at low-temperatures. It exhibited better performance than calcium chloride and had no effect on the type of hydration products, which remain the same as those of neat Class-G cement, i.e. the calcium silicate gel, Ca（OH）2 crystals and a small amount of ettringite AFt crystals. LS-A provides an effective way to guarantee the safety of cementing operations, and to solve the problems of low temperature and shallow water/gas flowing faced in deepwater cementing.

关键词： Deepwater cementing accelerator lithium chloride Class-G cement mechanism

Numerical modeling of DPSK pressure signals and their transmission characteristics in mud channels

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Petroleum Science 2009年第3期6卷 266-270页

作者： Shen Yue Su Yinao Li Gensheng Li Lin Tian Shouceng College of Physics Science and Technology China University of Petroleum Dongying Shandong 257061 China cnpc drilling research institute Beijing 100083 China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum Beijing 102249 China

A numerical model and transmission characteristic analysis of DPSK （differential phase shift keying） pressure signals in mud channels is introduced. With the control logic analysis of the rotary valve mud telemetry, a logical control signal is built from a Gate function sequence according to the binary symbols of transmitted data and a phase-shift function is obtained by integrating the logical control signal. A mathematical model of the DPSK pressure signal is built based on principles of communications by modulating carrier phase with the phase-shift function and a numerical simulation of the pressure wave is implemented with the mathematical model by MATLAB programming. Considering drillpipe pressure and drilling fluid temperature profile along drillpipes, the drillpipe of a vertical well is divided into a number of sections. With water-based drilling fluids, the impacts of travel distance, carrier frequency, drillpipe size, and drilling fluids on the signal transmission were studied by signal transmission characteristic analysis for all the sections. Numerical calculation results indicate that the influences of the viscosity of drilling fluids and volume fraction of gas in drilling fluids on the DPSK signal transmission are more notable than the others and the signal will distort in waveform with differential attenuations of the signal frequent component.

关键词： Measurement while drilling (MWD) modulation binary symbol mathematical model numerical simulation differential phase shift keying (DPSK) signal transmission characteristics

Mechanisms and field test of solution mining by self-resonating cavitating water jets

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Petroleum Science 2010年第3期7卷 385-389页

作者： Song Xianzhi Li Gensheng Yuan Jinping Tian Zhonglan Shen Ruichen Yuan Guangjie Huang Zhongwei State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China drilling Engineering research institute CNPC Beijing 100088 China

Rapid solution mining is the key to cavern construction in salt formations. Rapid solution mining technology with self-resonating cavitating water jets is described in this paper. It can generate three main physical effects： helical flow dissolution, self-resonating cavitating jet erosion, and ultrasonic waves. A self-resonating cavitating nozzle was also designed with the principles based on theory of fluid transients and hydro-acoustics. Under ambient pressure, the experimental results show that the impulse amplitude of pressure reaches a peak at a standoff distance of 5-13 times the nozzle outlet diameter and the cutting ability of self-resonating cavitating jets is twice that of conventional jets under the same conditions. Compared with the conventional mining method, the field test indicates that rapid solution mining technology with self-resonating cavitating jets can speed the construction by more than 2 times at the pocket stage of cavern development.

关键词： Cavitating jet underground storage helical flow rapid solution salt cavern

Non-Darcy flow in oil accumulation (oil displacing water) and relative permeability and oil saturation characteristics of low-permeability sandstones

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Petroleum Science 2010年第1期7卷 20-30页

作者： Zeng Jianhui Cheng Shiwei Kong Xu Guo Kai Wang Hongyu State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum Beijing 102249 China School of Natural Resources and Information Technology China University of Petroleum Beijing 102249 China cnpc Greatwall drilling Company Beijing 100101 China

Hydrocarbon resources in low-permeability sandstones are very abundant and are extensively distributed. Low-permeability reservoirs show several unique characteristics, including lack of a definite trap boundary or caprock, limited buoyancy effect, complex oil-gas-water distribution, without obvious oil-gas-water interfaces, and relatively low oil （gas） saturation. Based on the simulation experiments of oil accumulation in low-permeability sandstone （oil displacing water）, we study the migration and accumulation characteristics of non-Darcy oil flow, and discuss the values and influencing factors of relative permeability which is a key parameter characterizing oil migration and accumulation in low-permeability sandstone. The results indicate that： 1） Oil migration （oil displacing water） in low- permeability sandstone shows non-Darcy percolation characteristics, and there is a threshold pressure gradient during oil migration and accumulation, which has a good negative correlation with permeability and apparent fluidity; 2） With decrease of permeability and apparent fluidity and increase of fluid viscosity, the percolation curve is closer to the pressure gradient axis and the threshold pressure gradient increases. When the apparent fluidity is more than 1.0, the percolation curve shows modified Darcy flow characteristics, while when the apparent fluidity up＂ non-Darcy percolation curve; 3） Oil-water is less than 1.0, the percolation curve is a ＂concave- two-phase relative permeability is affected by core permeability, fluid viscosity, apparent fluidity, and injection drive force; 4） The oil saturation of low- permeability sandstone reservoirs is mostly within 35%-60%, and the oil saturation also has a good positive correlation with the permeability and apparent fluidity.

关键词： Non-Darcy flow relative permeability oil saturation low-permeability sandstone

NUMERICAL SIMULATION OF TRANSIENT CUTTINGS TRANSPORT WITH FOAM FLUID IN HORIZONTAL WELLBORE

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Journal of Hydrodynamics 2009年第4期21卷 437-444页

作者： WANG Rui-he CHENG Rong-chao WANG Hai-ge BU Yu-huan College of Petroleum Engineering China University of Petroleum Dongying 257061 China cnpc drilling research institute Beijing 100195 China

With considering the interlayer mass transfer and fluid influx from the reservoir, a one-dimensional two-layer hydraulic model was established to describe the mechanism of transient cuttings transport with foam fluid in horizontal well section. The model was numerically calculated based on the modified SIMPLE algorithm, and the height of cuttings bed was predicted by the trial-and-error method. Sensitivity analysis was conducted on the affecting factors on the cuttings transport performance. Results show that cuttings deposition moves along the horizontal wellbore from the drilling bit, and finally achieves a steady state with dynamic balance. Dimensionless cuttings bed height decreases with the increase of foam quality or foam flow rate, but increases with the increase of drillpipe eccentricity, cuttings size or drilling rate. The influx of water and gas from the reservoir is helpful to improve the cuttings transport efficiency with foam. The proposed model offers theoretical guidelines for hydraulic parameter design and hole cleaning control in foamed horizontal drilling.

关键词： foam fluid horizontal wellbore drilled cuttings theoretical model numerical simulation

Investigation of effects of clay content on F-Ф relationship by Lattice gas automation using digital rock model

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Petroleum Science 2011年第2期8卷 170-176页

作者： Yue Wenzheng Tao GUo Chai Xiyuan Jiang Hongxiu Mu Hongwu State Key Laboratory of Petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China Key Laboratory of Earth Prospecting and Information Technology China University of Petroleum Beijing 102249 China cnpc Key Laboratory of Well Logging China University of Petroleum B eijing 102249 China Bohai drilling Engineering Company LTD Logging Company Tianjin 300280 China

The Lattice Gas Automation （LGA） method, which is improved by introducing a reflection coefficient for the border between phases to show its effect on current path, is used in this paper to simulate the current flow in digital rock for investigating the effects of clay content and clay distribution types on the relationship between formation factor（F） and rock porosity（φ）. The digital rock model is constructed by simulating a natural deposit of matrix particles with different shapes and radius. Based on the simulation results, it was found that both dispersed clay and laminated clay can lead to a non-Archie relationship of F-φ. The non-Archie effect of laminated clay on the F-φ relationship was more significant than that of dispersed clay. Moreover, a realistic model is developed in this work for quantitatively describing the effect of clay content （Denoted as Vsh） on parameters a and m. These study results have further demonstrated the validity of LGA in study of electrical transport properties at a pore scale.

关键词： Formation factor non-Archie Lattice gas automation porosity clay content claydistribution