Integrated design and control technology of liner completion and drilling for horizontal wells

Aiming at the problems of large load of rotation drive system,low efficiency of torque transmission and high cost for operation and maintenance of liner steering drilling system for the horizontal well,a new method of liner differential rotary drilling with double tubular strings in the horizontal well is proposed.The technical principle of this method is revealed,supporting tools such as the differential rotation transducer,composite rotary steering system and the hanger are designed,and technological process is optimized.A tool face control technique of steering drilling assembly is proposed and the calculation model of extension limit of liner differential rotary drilling with double tubular strings in horizontal well is established.These results show that the liner differential rotary drilling with double tubular strings is equipped with measurement while drilling(MWD)and positive displacement motor(PDM),and directional drilling of horizontal well is realized by adjusting rotary speed of drill pipe to control the tool face of PDM.Based on the engineering case of deep coalbed methane horizontal well in the eastern margin of Ordos Basin,the extension limit of horizontal drilling with double tubular strings is calculated.Compared with the conventional liner drilling method,the liner differential rotary drilling with double tubular strings increases the extension limit value of horizontal well significantly.The research findings provide useful reference for the integrated design and control of liner completion and drilling of horizontal wells.

Pre-Drilling Prediction Techniques on the High-Temperature High-Pressure Hydrocarbon Reservoirs Offshore Hainan Island,China

Decreasing the risks and geohazards associated with drilling engineering in high-temperature high-pressure(HTHP) geologic settings begins with the implementation of pre-drilling prediction techniques(PPTs). To improve the accuracy of geopressure prediction in HTHP hydrocarbon reservoirs offshore Hainan Island, we made a comprehensive summary of current PPTs to identify existing problems and challenges by analyzing the global distribution of HTHP hydrocarbon reservoirs, the research status of PPTs, and the geologic setting and its HTHP formation mechanism. Our research results indicate that the HTHP formation mechanism in the study area is caused by multiple factors, including rapid loading, diapir intrusions, hydrocarbon generation, and the thermal expansion of pore fluids. Due to this multi-factor interaction, a cloud of HTHP hydrocarbon reservoirs has developed in the Ying-Qiong Basin, but only traditional PPTs have been implemented, based on the assumption of conditions that do not conform to the actual geologic environment, e.g., Bellotti's law and Eaton's law. In this paper, we focus on these issues, identify some challenges and solutions, and call for further PPT research to address the drawbacks of previous works and meet the challenges associated with the deepwater technology gap. In this way, we hope to contribute to the improved accuracy of geopressure prediction prior to drilling and provide support for future HTHP drilling offshore Hainan Island.

Novel Water-Based Drilling and Completion Fluid Technology to Improve Wellbore Quality During Drilling and Protect Unconventional Reservoirs

The efficient exploration and development of unconventional oil and gas are critical for increasing the self-sufficiency of oil and gas supplies in China.However,such operations continue to face serious problems(e.g.,borehole collapse,loss,and high friction),and associated formation damage can severely impact well completion rates,increase costs,and reduce efficiencies.Water-based drilling fluids possess certain advantages over oil-based drilling fluids(OBDFs)and may offer lasting solutions to resolve the aforementioned issues.However,a significant breakthrough with this material has not yet been made,and major technical problems continue to hinder the economic and large-scale development of unconventional oil and gas.Here,the international frontier external method,which only improves drilling fluid inhibition and lubricity,is expanded into an internal-external technique that improves the overall wellbore quality during drilling.Bionic technologies are introduced into the chemical material synthesis process to imitate the activity of life.A novel drilling and completion fluid technique was developed to improve wellbore quality during drilling and safeguard formation integrity.Macroscopic and microscopic analyses indicated that in terms of wellbore stability,lubricity,and formation protection,this approach could outperform methods that use typical OBDFs.The proposed method also achieves a classification upgrade from environmentally protective drilling fluid to an ecologically friendly drilling fluid.The developed technology was verified in more than 1000 unconventional oil and gas wells in China,and the results indicate significant alleviation of the formation damage attributed to borehole collapse,loss,and high friction.It has been recognized as an effective core technology for exploiting unconventional oil and gas resources.This study introduces a novel research direction for formation protection technology and demonstrates that observations and learning from the natural world can provide an inexhaustible source of ideas and inspire the creation of original materials,technologies,and theories for petroleum engineering.

Intelligent Drilling and Completion:A Review

The application of artificial intelligence(AI)has become inevitable in the petroleum industry.In drilling and completion engineering,AI is regarded as a transformative technology that can lower costs and significantly improve drilling efficiency(DE),In recent years,numerous studies have focused on intelligent algorithms and their application.Advanced technologies,such as digital twins and physics-guided neural networks,are expected to play roles in drilling and completion engineering.However,many challenges remain to be addressed,such as the automatic processing of multi-source and multi-scale data.Additionally,in intelligent drilling and completion,methods for the fusion of data-driven and physicsbased models,few-sample learning,uncertainty modeling,and the interpretability and transferability of intelligent algorithms are research frontiers.Based on intelligent application scenarios,this study comprehensively reviews the research status of intelligent drilling and completion and discusses key research areas in the future.This study aims to enhance the berthing of AI techniques in drilling and completion engineering.

Drilling and completion technologies of coalbed methane exploitation: an overview

Coalbed methane(CBM)drilling and completion technologies(DCTs)are signifcant basis for achieving efcient CBM exploration and exploitation.Characteristics of CBM reservoirs vary in diferent regions around the world,thereby,it is crucial to develop,select and apply the optimum DCTs for each diferent CBM reservoir.This paper frstly reviews the development history of CBM DCTs throughout worldwide and clarifes its overall development tendency.Secondly,diferent well types and its characteristics of CBM exploitation are summarized,and main application scopes of these well types are also discussed.Then,the key technologies of CBM drilling(directional drilling tools,measurement while drilling,geo-steering drilling,magnetic guidance drilling,underbalanced drilling and drilling fuids),and the key technologies of CBM completion(open-hole,cavity and under-ream completion,cased-hole completion,screen pipe completion and horizontal well completion)are summarized and analyzed,it is found that safe,economic and efcient development of CBM is inseparable from the support of advanced technologies.Finally,based on the current status of CBM development,the achievements,existing challenges and future prospects are summarized and discussed from the perspective of CBM DCTs.

The study of formulation and performance of formate drilling and completion fluid system

Formate drilling and completion fluid system is a new type of clean organic salt brine system which has been developed from inorganic salt brine drilling fluid system. It is beneficial to protecte and find hydrocarbon reservoir. Due to the solid free system, the damage of solid phase particles on reservoir, especially low permeability oil and gas layer, can be greatly eliminated, at the same time, drilling fluid and completion fluid have greater compatibility. It will avoid that precipitation which is not compatible with drilling and completion fluid and generates damages on reservoir. And because mud cake of the solid free system is thin and resilient, it is conductive to improve cementing quality greatly. Experiments show that the formate drilling and completion system has good rheological property, strong inhibition ability, good lubricating performance, good compatibility with reservoir rocks and formation water at high temperature.

Research and application of non-clay low damage temporary bridging drilling/completion fluids system

Following the basic theory of protecting gas-reservoirs from damage with the temporary bridging technology,inert calcium carbonate (CaCO3) particles,whose diameter is consistent with the size of pores or apertures in the reservoir,were selected as the bridging agent,and modified resolvable starch was selected as filtration loss reducing particles to form the non-clay low damage temporary bridging drilling/completion fluids system (NLTDFS). Under the simulated condition of the well bottom during real drilling,NLTDFS was used to conduct dynamic and static damage experiments of cores for 48 hours,respectively,and then the experimented cores were permeated with pure nitrogen from the undamaged end to the damaged one to measure their recovery of permeability. The results showed that the permeability recovery rate of the core reached 90% or so,and the damaged depth was less than 1 cm,which demonstrates that NLTDFS has higher temporary bridging effectiveness and lower damage to the gas-reservoir than other drilling fluids system. NLTDFS has been used to drill many horizontal wells,and four of them have obtained high yield of natural gas. The yield of natural gas of LP1 well reached 85×104 m3/day after completion with the rump pipe. The formation of the stable well wall and smooth drilling led to an API loss less than 4 mL and an HTHP loss less than 15 mL.

Permittivity of composites used for Luneburg lens antennas by drilling holes based on 3-D printing technique

Due to the attractive performances such as the ability of beam focus,broadband,multi-beam scanning and other features,Luneburg lens antennas are applied in multi-beam antenna,which overcomes the problem of gain loss produced by multi-beam parabolic antenna.Based on 3-D printing technique,Luneburg lens antennas by drilling holes are studied.Permittivity and loss tangent of the equivalent lens materials can be influenced by original materials,hole shapes,hole directions,and porosity.After tests,polystyrene with waxes may be the most appropriate materials for Luneburg lens with high strength.Permittivity with the shape of triangle is the lowest due to the homogeneity.Relative permittivities with the direction at a range of 15°-45°are lower while loss tangent at a range of 0°-30°.Radial directional holes are more appropriate for Luneburg lens.The relative permittivity is decreased with the increment of porosity.After calculations,the forecasts calculated by Looyenga and A-BG theory are more precise.Finally,Luneburg lens with two layers is fabricated by 3-D printing.

Nonlinear Dynamic Analysis of Deepwater Drilling Risers Subjected to Random Loads

Excited by ocean currents, random wave and vessel motion, deepwater drilling risers exhibit significant dynamic response. In time domain, a method is proposed to calculate the nonlinear dynmnic response of deepwater drilling risers subjected to random wave and dynamic large displacement vessel motion boundary condition. Structural and functional loads, external and intemal pressure, free surfaee effect of irregular wave, hydrodynamic forees induced by current and wave, as well as wave and low frequency （drift） motion of the drilling vessel are all accounted for. An example is presented which illustrates the application of the proposed method. The study shows that long term drift motion of the vessel has profound effect on the envelopes of bending stress and lateral displacement, as well as the range of lower flex joint angle of the deepwater riser. It can also be concluded that vessel motion is the principal dynamic loading of nonlinear dynamic response for the deepwater risers rather than wave force.

“Push back” technique: A simple method to remove broken drill bit from the proximal femur

Broken drill bits can be difficult to remove from the proximal femur and may necessitate additional surgical exploration or special instrumentation.We present a simple technique to remove a broken drill bit that does not require any special instrumentation and can be accomplished through the existing incision.This technique is useful for those cases where the length of the broken drill bit is greater than the diameter of the bone.

Kicks Controlling Techniques Efficiency in Term of Time

Kicks are the result of under balance drilling operation. Time consumed to control the kicks will be different in depending on the controlling technique. Drilling fluid considered as a first barrier to control formation pressure and well kicks. Any advance in drilling fluids leads to more controlled operation in term of time. This paper will follow the general increasing profile of pressure before entering the reservoir. Both methods of well controlling technique;circulating techniques and non-circulating have been implemented in many oil blocks. The process of designing and casing selection, setting depth and many other issues is predominately dependent on the utilization of accurate values of formation pressure. Formation pressures used to design safe mud weights to overcome fracturing the formation and prevent well kicks. Hence the emphasis has been placed on the practical utilization of kicks pressure near the reservoir. The presented relationships will help the engineer to better understand lithological columns and reduce potential hole problems during the kick appearance. Selecting the best well controlling practical method can lead to not harming the reservoir and more production later. Changes in some drilling fluid properties have been proposed with increasing the depth without damaging the reservoir. Suggestions in relation to the casing setting point of the intermediate section are also proposed. Standard equations with proper modification for gases and safety margin have been proposed for the future drilling operation in oil fields above the reservoir.

Drill-in钻井液在苏丹37区水平井中的应用

Palouge油田位于苏丹37区上尼罗州的Melut盆地,属典型的高渗油层,储层压力已降低,易被污染和损害,同时储层上部的Adar和Yabus泥岩水敏性强,易发生缩径坍塌。开发出了Drill-in钻井液,利用KCl和聚合醇保证钻井液的强抑制性和防塌性,利用聚合醇和QS-2的屏蔽暂堵作用减少油气层伤害;采用碳酸钙和可降解的有机处理剂作主要成分,使泥饼得到有效的化学和生物降解,以提高储层的渗透率恢复率。Drill-in钻井液在该油田水平井的使用收到了良好的效果,基本满足了钻井施工的需要,使该油田水平井产能平均增加了12.4%。

完全性脊髓横断后排尿次数对神经源性膀胱模型大鼠成模率的影响

背景:脊髓损伤常导致逼尿肌反射亢进型神经源性膀胱,目前对其发病机制和治疗缺乏明确认识,建立稳定可靠的动物模型对揭示疾病的病理机制和探索治疗方法具有重要影响。目的:探究完全性脊髓横断术后辅助排尿次数对神经源性膀胱模型大鼠的影响,以提高神经源性膀胱模型大鼠术后生存率及成模率。方法:从46只雌性SD大鼠中按随机数字表法抽取6只为假手术组,剩余40只大鼠完全性脊髓横断造模后随机分为每日排尿0,1,3,5次组,每组10只。术后19 d内每隔3 d测量残余尿量,术后第19天时观察存活及成模情况,进行尿流动力学检测及离体逼尿肌肌条收缩实验。结果与结论:①存活率及成模率:每日排尿0次组存活率10%,成模率10%;每日排尿1次组存活率20%,成模率10%;每日排尿3,5次组存活率70%,成模率70%;②残余尿量:与假手术组相比,术后第3,6,9,12,15天,每日排尿3,5次组的残余尿量显著增加(P<0.01);术后第18天,每日排尿3,5次组的残余尿量增多(P<0.05);与每日排尿3次组相比,术后第6天,每日排尿5次组的残余尿量减少(P<0.05),术后第3,9,12,15,18天,每日排尿5次组的残余尿量无统计学差异;③尿流动力学:与假手术组相比,每日排尿3,5次组大鼠的漏尿点压差明显减小(P<0.01),膀胱最大容量显著增大(P<0.01);与每日排尿3次组相比,每日排尿5次组的漏尿点压差和膀胱最大容量均无统计学差异;④离体逼尿肌肌条收缩实验:与假手术组相比,每日排尿3,5次组逼尿肌肌条收缩幅度和频率显著减少(P<0.01);与每日排尿3次组相比,每日排尿5次组的逼尿肌肌条收缩幅度和频率均无统计学差异。结果表明:辅助排尿是成功构建逼尿肌反射亢进型神经源性膀胱模型的影响因素之一,每日排尿3次或5次无明显差异,结合实际工作量和成模率,建议每日排尿频率至少3次及以上。

Research and application of water jet technology in well completion and stimulation in China

In recent years, rapid progress in the use of high pressure water jets （HPWJ） has been made in oil and gas well drilling, completion, and stimulation; and good results have been achieved in field applications. Advances in technologies and developments of well completion and stimulation with hydrajet are reviewed in this paper. Experiments were conducted to study the characteristics of abrasive water jetting and to optimize jet parameters, which can provide methods for the well completion and hydrajet fracturing. Deep-penetrating hydrajet perforating can create a 2-3 m clean hole with a diameter of 20-35 mm. Multilayer hydrajet fracturing is a process whereby multiple layers are stimulated in a single run without using mechanical packers, thereby reducing operation procedure and risk. Multilateral radial wells can be drilled using hydraulic jetting up to 100 m in length. The technique to remove sand particles and plugs with rotating self-resonating cavitating water jets in horizontal wellbores has been developed and oilfield-tested, which shows promising, cost effective prospects.

The q-analogues of two-mode squeezed states constructed by virtue of the IWOP technique

The q-analogues of two-mode squeezed states are introduced by virtue of deformation quantization methods and the technique of integration within an ordered product （IWOP） of operators. Some new completeness relations about these squeezed states composed of the bra and ket which are not mutually Hermitian conjugates are obtained. Furthermore, the antibunching effects of the two-mode squeezed vacuum state S＇s（τ） │00） are investigated. It is found that, in different ranges of the squeezed parameter τ, both modes of the state exhibit the antibunching effects and the two modes of the state are always nonclassical correlation.

Evaluation of the Functional Impression Technique with Various Impression Materials on the Surface Topography of Dental Stone Casts and Their Effect on Retention

Background: The accuracy of the final prosthesis is affected by the final impression technique and master cast production. The aim of the present study was to evaluate the effect of the functional impression technique with various impression materials on the surface characteristic of dental stone casts and their clinical effect on the retention of complete dentures. Method: Specimens of three impression materials/stone casts were fabricated. The specimens of the impression materials/stone casts were divided into three equal groups (I, II, and III). The impression materials used were as follows: tissue conditioner group (I), zinc oxide (ZEO) (group II) and poly (vinyl siloxane) (PVS) (group III). Cylindrical split aluminium moulds were designed to receive the impression materials and the stone mixture. The surface roughness of the stone cast specimens of the three groups (I, II, and III) was measured with a surface profilometer and analyzed by a scanning electron microscope. A clinical study included five severely resorbed mandibular edentulous alveolar ridges and edentulous maxillary arches. Each subject received three heat-cured acrylic resin dentures, fabricated using the functional impression technique. The three dentures were identical except for the different impression materials used from Groups I, II and III. The retentive force of each denture for each subject was measured. Result: The results of this study revealed that the mean value of surface roughness of the stone cast surface of group I was higher than group II and group III. A statistically significant difference was observed in surface roughness and the retentive dislodging force between the three studied groups. Although using a tissue conditioner as a functional impression material led to a high level of surface roughness and good retention, it could not produce the same smooth surface quality of PVS or ZEO. These data were supported by SEM analysis. The complete dentures for these patients require important oral and denture hygiene care. Conclusion: Complete dentures made using functional impression technique with PVC as a final impression material are more comfortable, retentive and stable.

A new analytical algorithm for computing probability distribution of project completion time

An analytical algorithm was presented for the exact computation of the probability distribution of the project completion time in stochastic networks,where the activity durations are mutually independent and continuously distributed random variables. Firstly,stochastic activity networks were modeled as continuous-time Markov process with a single absorbing state by the well-know method of supplementary variables and the time changed from the initial state to absorbing state is equal to the project completion time.Then,the Markov process was regarded as a special case of Markov skeleton process.By taking advantage of the backward equations of Markov skeleton processes,a backward algorithm was proposed to compute the probability distribution of the project completion time.Finally,a numerical example was solved to demonstrate the performance of the proposed methodology.The results show that the proposed algorithm is capable of computing the exact distribution function of the project completion time,and the expectation and variance are obtained.

Minimally Invasive Surgical Technique in Double Aortic Arch with Distal Atretic Left-Side in Infant:From a Single-Surgeon Clinical Experience

Background:Double aortic arch(DAA)with distal left-sided aortic arch atresia(LAAA)can form complete vascular ring by ligamentum connection.We aimed to introduce an uncommon DAA-LAAA diagnosis and treatment by the minimally invasive surgical technique(MIST).Methods:We retrospectively reviewed 7 cases of DAA-LAAA that were treated from January 2017 to July 2021.All infant patients underwent surgical repair by minimally invasive surgical technique.Mean follow-up was 14.43 months(range,5–21 months).Results:There were seven patients with DAA-LAAA,including six males and one female.Median age was 19.29 months(range,9.0–29.0 months).Median weight was 11.30 kg(range,9.6–13.0 kg).Three patients were found severe tracheal compression by cardiac computed tomography angiography(cCTA).Six patients with isolated DAA-LAAA were performed operations through left subaxillary minithoracotomy,and one patient with ventricular septal defect(VSD)was performed operation concurrently under the cardiopulmonary bypass(CPB)through right subaxillary minithoracotomy.All patients had symptom improvement in the postoperative period and discharged successfully.Follow-up data showed good results in short-term.Conclusions:We introduce a new surgical pathway for DAA-LAAA treatment with good symptomatic relief in short-term.MIST is a safe,feasible and economical approach for infant patients.

Laboratory Evaluation Procedures of Formation Damage Induced by Completion Fluids in Horizontal Wells

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中国石化超深层钻完井关键技术挑战及展望

超深层是中国石化油气勘探开发的重要增储上产领域。针对超深层勘探开发需求和高温高压及复杂地质环境带来的工程挑战,中国石化持续开展关键技术攻关,在钻完井基础理论和方法、钻完井装备、高温井筒工作液、耐高温井下工具仪器和完井测试等方面取得关键技术进展,保障了120口超8 000 m油气井的安全钻探,钻深能力突破9 000 m,助推塔里木盆地顺北大型超深油气田建设、四川盆地海相特深层油气勘探开发突破,为保障超深层油气勘探开发提供了有力的工程技术支撑。随着油气勘探开发不断向更深层推进,技术升级转型需求日益迫切,需进一步夯实理论研究基础,突破耐高温关键工具仪器和井筒工作液,加快推进钻完井工程技术向数智化转型,为保障深层、超深层油气高效勘探开发和加快技术升级转型提供工程技术支撑。