Temperature prediction model in multiphase flow considering phase transition in the drilling operations

The study considers gas compression properties,gas slippage,back pressure(BP),phase transition(PT),well depth,and differences in gas-liquid physical properties.A new temperature model for multiphase flow is proposed by considering phase transition in the drilling process.The mathematical model of multiphase flow is solved using the finite difference method with annulus mesh division for grid nodes,and a module for multiphase flow calculation and analysis is developed.Numerical results indicate that the temperature varies along the annulus with the variation of gas influx at the bottom of the well.During the process of controlled pressure drilling,as gas slips along the annulus to the wellhead,its volume continuously expands,leading to an increase in the gas content within the annulus,and consequently,an increase in the pressure drop caused by gas slippage.The temperature increases with the increase in BP and decreases in gas influx rate and wellbore diameter.During gas influx,the thermal conductivity coefficient for the gas-drilling mud two phases is significantly weakened,resulting in a considerable change in temperature along the annulus.In the context of MPD,the method of slightly changing the temperature along the annulus by controlling the back pressure is feasible.

Treatment of drilling wastewater from a sulfonated mud system

Treatment of drilling wastewater from a sulfonated drilling mud system in the Shengli Oilfield, East China, was studied. The wastewater was deeply treated by a chemical coagulationcentrifugal separation-ozone catalytic oxidation combined process. The factors （i.e. pH value, chemical dosage, reaction time, etc.） influencing the treatment effect were investigated, and pH = 7 was determined as optimal for the coagulation; polymeric aluminum chloride （PAC） was selected as the optimal coagulant with a dosage of 18 g/L; cationic polyacrylamide （CPAM） with molecular weight of 8 million was selected as the optimal coagulant aid with an optimum dosage of 8 mg/L; and the optimal condition of catalytic ozonation was found to be a pH of 12 and an oxidation time of 40 min. The results showed that the combined treatment process was effective. The oil content and suspended solids content of the effluent reached the first class discharge standard according to China＇s standard GB 8978-1996 （Integrated Wastewater Discharge Standard） and the chemical oxygen demand （COD） decreased to 195 mg/L from 2.34×10^4 mg/L after coagulation process and ozone oxidation at pH = 12 for 40 min.

A novel oil-in-water drilling mud formulated with extracts from Indian mango seed oil

Drilling muds with less environmental impact are highly desired over conventional diesel-based mud systems,especially in light of the emerging strict environmental laws.In this article,a novel oil-in-water(O/W)emulsion drilling fluid formulated with a methyl ester extracted from Indian mango seed oil was evaluated.The effect of the weight percent of different constituents of the emulsion/suspension including the oil phase,bentonite,and polyanionic cellulose polymer on the rheology and the fluid loss was examined.The methyl ester oil phase/mud system displayed superior physical,chemical,rheological and filtration properties relative to the diesel and the mango seed oil.Eco-toxicity of the methyl ester and diesel(O/W)emulsion mud systems was assessed using the acute lethal concentration test.The Indian mango methyl ester(O/W)emulsion mud displayed much less impact on fish population.Flow characteristics collected from the flow model at 85°C suggested excellent shear thinning behavior of the Indian mango methyl ester(IMME)(O/W)emulsion mud.Moreover,the IMME(O/W)emulsion displayed strong pseudoplastic behavior,an attractive feature in a drilling mud,with increasing clay content and polymer concentration.The methyl ester mud was thermally stable over a wide range of the constituent concentrations.Furthermore,a particle size analysis revealed that engineered drilling muds targeting suspension of particles with certain size range can be formulated by changing the volume fraction of the methyl ester in the mud system.

Preparation of High Effective Flocculant for High Density Waste Drilling Mud

To satisfy the requirement on the separation of solid and liquid in waste drilling mud, prepare a high effective floccu-lant for high density waste drilling mud used starch, 2-Trimethylammonium ethyl methacrylate chloride (DMC) and acrylamide (AM). The result showed that when the ratio of starch, DMC and AM was 2:1:3, the weight of initiator (po-tassium persulfate) was 0.2% of the AM, reaction temperature was 65℃ and reaction time was 5h, the performance of product was the best. The water content in filter cake was 27.6% after the waste drilling mud disposed by the optimization flocculant. The flocculent effect of optimization flocculant was superior to that of other flocculant in market.

Development of key additives for organoclay-free oil-based drilling mud and system performance evaluation

Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.

Axial Vibration Analysis of the Mud Recovery Line on Deepwater Riserless Mud Recovery Drilling System

The series connection of multistage pumping module is the common concept of deepwater riserless mud recovery drilling system. In this system, the influence of the mass of pumping module on the vibration of mud recovery line cannot be ignored, and the lumped mass method has been utilized to discretize the mud recovery line. Based on the analysis of different boundary conditions, the paper establishes the axial forced vibration model of the mud recovery line considering the seawater damping, and the vibration model analysis provides the universal solution to the vibration model. An example of the two-stage pumping system has been used to analyze the dynamic response of mud recovery line under different excited frequencies. This paper has the important directive significance for the application of riserless mud recovery drilling technology in deepwater surface drilling.

High temperature geothermal drilling mud

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Calculation of safe drilling mud density window for shale formation by considering chemo-poro-mechanical coupling effect

It is difficult to define safe drilling mud density window for shale sections.To solve this problem,the general Biot effective stress principle developed by Heidug and Wong was modified.The Weibull statistical model was used to characterize the hydration strainrelated strength damage.Considering drilling fluid sealing barrier on shale,a calculation method of safe drilling mud density has been established for shale formation under drilling fluid sealing-inhibition-reverse osmosis effect,combined with a flow-diffusion coupling model.The influence of drilling fluid sealing and inhibiting parameters on safe drilling mud density window was analyzed.The study shows that enhancing drilling fluid sealing performance can reduce the pore pressure transmission and solute diffusion;the inhibiting performance of drilling fluid,especially inhibition to strength damage,is crucial for the wellbore collapse pressure of shale section with significant hydration property.The improvement of drilling fluid sealing and inhibition performance can lower collapse pressure and enhance fracturing pressure,and thus making the safe drilling fluid density window wider and the collapse period of wellbore longer.If there is osmosis flow in shale,induced osmosis flow can make the gap between collapse pressure and fracturing pressure wider,and the stronger the sealing ability of drilling fluid,the wider the gap will be.The safe drilling mud density window calculation method can analyze the relationships between collapse pressure,fracturing pressure and drilling fluid anti collapse performance,and can be used to optimize drilling fluid performance.

Microbial Assessment of Used Drilling Mud and Mix Cement Fluid for Production Well

Drilling fluids and mud additives are generally acknowledged as potential sources of contamination in deep drilling programs, as they may contain high concentration of nutrients for subsurface microorganisms. Microorganisms introduced into drilling process cause a number of problems that can lead to significant costs for the industry. Numerous studies have shown that biogenic sulfide production in oil and natural gas fields have led to a number of problems, including reservoir plugging, reservoir souring, reduced product quality, and corrosion of metal-containing equipment. The aim of this study is to determine the microbial contamination of water drilling mud and cement Mix fluid at two Saudi Aramco well SA-10 ＆ SA-12 and to adequately perform microbial assessment for the well both wells. Microbiological analyses were conducted to evaluate the level of contamination by TB （total bacterial） and SRB （sulfate reducing bacteria） using and q-PCR （quantitative poly chain reaction） technique. Microbial results for SA-10 indicated that total bacteria were 2.21 × 103/mL for mix fluid sample and 1.22 × 105/mL for drilling water sample. In addition, microbial results for total SRB were 1.65 × 102/mL and 1.34 × 102 mL, respectively. Moreover, microbial results for SA-12 indicated 5.89 × 105/mL of total bacteria and 98/mL of SRB in the sample.

Preparation of Nano-Modified Polyacrylamide and Its Application on Solid-Liquid Separation in Waste Drilling Mud

To satisfy the requirement on solid-liquid separation in high-density waste drilling mud, prepare the nano-modified polyacrylamide(PAM) flocculant for high density waste drilling mud by in-situ dispersion method, direct dispersion method and simultaneous formation method. The result showed the flocculent effect of nano-modified polyacrylamide prepared by simultaneous formation method was the best. When the content of water glass and acrylamide(AM) were respectively 3% and 15% , reaction temperature was 60?C and reaction time was 3h, the performance of product was the best. The water content in filter cake was 24.32% after the waste drilling mud disposed by the optimization flocculant. The flocculent effect of optimization flocculant was superior to that of other flocculant in market.

OBM-1油基钻井液用聚合物微球

目前的堵漏材料大多针对水基钻井液来研发,对油基钻井液的适用性不强。采用反相乳液聚合方法,通过引入亲油组分,合成了一种油基钻井液用聚合物微球OBM-1。OBM-1基本呈球形,粒径分布处于1~100μm之间,在油基钻井液中具有良好的分散能力。加入3%OBM-1后,能够保持油基钻井液流变性能稳定,有效降低高温高压滤失量和封闭滤失量。高温高压滤失实验表明,OBM-1可使120℃的高温高压滤失量降低50%,其抗温可达150℃;封堵承压实验表明,OBM-1能够封堵5~40μm砂盘,承压达15 MPa;封闭漏失实验表明,OBM-1能够有效封堵20~40目石英砂制备的砂床。现场应用结果表明,OBM-1可有效降低漏失量,试验井段每米油基钻井液消耗量同比下降30.3%,很大程度节约了钻井成本。该研究为使用油基钻井液进行安全高效钻进提供了有力的技术支持。

STRUCTURE-PROPERTY RELATIONSHIP OF POLYELECTROLYTES AND ITS APPLICATION IN STABILIZING DRILLING-MUD IN PRESENCE OF SALTS

A new polyelectrolyte (SPU) has been prepared. It can depress the water-loss of drilling-mud much more effective than the commonly used acrylic polyelectrolytes even in 30% NaCl solution. SPU has phenyl group in the backbone with -SO_3^- in the side chain while the acrylic polyelectrolytes have C—C and -COO^- respectively, there exists an intrinsic relationship between the structure of polymer and its tolerance to salts, it has been found: 1) The adsorption amount of polymer on clay is related closely to the flexibility of polymer chain. 2) The salt-tolerance of -SO_3^- is superior to -COO-. 3) Both SPU-mud and HPAN-mud are plastic fluids. The dependence of yield point on salts relates to the molecular weight of polymer and hydration of ionogenic group, which is quite different for SPU-mud and HPAN-mud. 4 ) The extent of raising zeta-potential of base-mud by SPU is greater than by HPAN, but the extent of dropping zeta-potential of SPU-mud by NaCI is smaller than HPAN-mud. According to these results we suppose the salt-tolerance of SPU-mud is attributed mainly to hydration of -SO_3^- and that of HPAN-mud mainly to network structure formed in the drilling-mud.

Effect of Cassava Starch and Sodium Carbonate on the Properties of Local Drilling Mud: Beneficiation to Improve the Rheological and Flow Properties of Locally Formulated Mud

Drilling mud is a key component in drilling operations and in accessing oil and gas reservoirs. Bentonite is applied as a viscosifier, fluid loss control agent, and as a weighting material in water-based drilling mud. The type of bentonite used in drilling mud formulation is sodium bentonite due to its high dispersion properties and high swelling capacity. Nigeria has a huge bentonite clay deposit resources which can be evaluated and enhanced in order to be utilized as drilling mud. However, bentonite clay from different parts of Nigeria was investigated and found to be calcium bentonite which is not suitable for drilling mud, because it has low swelling capacity and poor rheological properties. In this study, local bentonite obtained from Afuze, Edo state was used to formulate different samples of drilling mud with each treated using thermo-chemical beneficiation process with sodium carbonate and cassava starch, and then undergo characterization to identify the changes in physical properties and finally, draw comparison with API values for standard drilling mud. The results obtained from this study indicates that, the flow and rheological properties of the beneficiated drilling mud developed through thermo-chemical treatment, showed significant improvement compared to the untreated mud. Therefore, pure calcium bentonite from natural deposits in Nigeria can be modified to sodium bentonite and sufficiently used in drilling mud formulation.

考虑深井井下动力钻具影响的钻柱粘滑振动规律

油气勘探开发统计数据显示,深井钻井过程中粘滑振动频发,占钻进时长的50%以上,严重影响了钻井井下安全,延长了钻井周期,增加了钻井成本。由于深井钻柱结构较为复杂,井下动力钻具应用普遍,但动力钻具对井底钻头粘滑振动的影响规律缺乏深入研究,目前尚未有学者提出深井动力钻具下的钻柱全尺寸动力学模型。为此,基于弹簧集中质量原理,建立了包含井下动力钻具的粘滑振动仿真模型和螺杆钻具输出参数的计算模型,研究了螺杆钻具、扭力冲击器及两种工具复合使用对钻头粘滑振动的影响,并基于模型分析了现场实钻案例。研究结果表明:(1)使用螺杆钻具复合钻进时,转盘转速与螺杆转速对粘滑振动影响较大,复合转速越大,越有利于消除粘滑振动;(2)钻压和钻头尺寸越大,需要消除粘滑振动的转速就越大;(3)在保证水力参数的情况下,螺杆输出较高的扭矩和转速,能够有效地抑制钻头粘滑;(4)扭力冲击器和螺杆钻具复合使用情况下,当螺杆钻具的输出参数不足以抑制粘滑振动时,提高扭力冲击器的冲击扭矩和冲击频率,可降低螺杆钻具的临界转速,抑制井底粘滑振动。结论认为,该动力学模型可以为深井合理使用动力钻具、避免粘滑振动和提高机械钻速提供有效的技术支撑,该理论新认识在指导钻井现场钻进,提高钻井效率和降低钻井成本等方面具有重要的现实意义。

负压振动筛原理及在油基钻井液钻屑减量中的应用

经过几十年的发展,振动筛性能有很大提高,但其对钻屑的脱液能力已达极限。40年来,应用于钻井固控,效果不明显。十多年前,经过尝试与高频低幅振动相结合的真空过滤技术应用于钻井固控时,钻屑的脱液能力显著提高,排放钻屑体积大幅减小。近年来,多种负压振动筛在国内钻井中开展了应用试验。经过对常规振动筛复合负压过滤的负压振动筛的原理、主要技术参数、现场应用与国内外类似技术的对比分析及现场应用表明,所使用的负压振动筛的处理量、钻屑含液率、钻屑排放减少量、筛网寿命、能效、设备成本、使用经济效益等都均有明显优势。负压振动筛的应用对节能减排和实现“碳中和”具有重要作用,其逐渐替代常规振动筛,将是钻井固控技术发展的必然趋势。

水文水井钻探泥浆特征参数在线监测技术

水文水井钻探是开发地下水资源的一项重要技术手段,钻探过程中产生的泥浆排放会对生态环境造成一定程度的破坏。为对泥浆进行有效净化并循环利用,开展了泥浆在线监测方案的研究,首先利用管道黏度计对泥浆密度、表观黏度、塑性黏度、动切力进行实时监测,然后通过预先训练基于泥浆密度、流变性参数和含砂量的神经网络模型,预测经过固相控制之后的泥浆中的含砂量。结果表明:通过管道黏度计监测的泥浆密度、表观黏度、塑性黏度、动切力的平均误差分别为0.2%、1.7%、3.4%、3.7%;通过神经网络模型预测的含砂量的平均误差为15.9%,预测模型不依赖模型训练中使用的泥浆配方,能够适用于相同体系的其他泥浆配方,表明预测模型具有一定的泛化性。该泥浆在线监测系统能够满足绿色勘查的要求,适合水文地质及水井钻探的现场应用。

基于钻井泥浆优化设计水淹层识别技术研究

南堡凹陷深层岩性复杂、物性、含油性变化大,油气层测井特征非常复杂,识别难度大。注淡水开发加剧了储层水性的复杂程度,电性特征更加复杂,以电阻率-孔隙度为主的常规测井系列水淹层定性识别技术具有较大的局限性。由于自然电位测井正幅度差异能够有效指示储层水性变化,通过控制钻井泥浆矿化度,使自然电位在油层处呈现较小或微幅度正差异,在水淹层处呈现较大幅度正差异来指示储层水性变化,突出水淹层、识别隐蔽油气层。现场应用实践表明,通过合理控制钻井泥浆矿化度,利用自然电位正幅度差异指示储层水性变化,能够对水淹层及隐蔽油气层进行识别,取得了良好应用效果。

铀矿地质钻探移动式泥浆净化设备设计

环保要求和泥浆性能维护在地质勘探中的重要性日渐突显,使得铀矿钻探建设对泥浆清洁处理的标准变得更为严格。基于铀矿钻探工作单孔施工周期较短、机台搬家频次较高以及泥浆处理量较小的特点,研制了一种适用于砂岩型铀矿钻探的移动式泥浆净化设备。该设备采用模块化集成设计,主要由泥浆收集系统、除砂系统、自动化控制系统等组成,整合泥浆收集、净化、排放等多项传统泥浆处理设备设施及工艺,并可实现拖拽行走,在机台短途搬迁时能有效节约人力、物力。现场试验证明,该设备在砂岩型铀矿钻探过程中实现了优良的环保效果和经济效益,达成了一次配浆多孔使用和泥浆零排放的目标,并提高了钻孔质量。

深海钻探泥浆举升系统双泵协同机制研究

深海钻探泥浆举升系统在无隔水管泥浆循环钻井(RMR)工艺中具有关键作用。为了提升举升系统的安全余量和适应性,本文对多泵串并联机制进行了深入研究,详细描述了泥浆举升泵的串并联结构设计和工作原理,探讨了串联和并联运行时流量与扬程的关系以及泵组串并联工况点的数解法和图解法步骤。进一步地,利用模型泵实测特性曲线,使用图解法获取了双泵串并联工况下的Q-H特性曲线和工况点,并提出了双泵协同控制的建议。