High Productivity Gas Research Articles

Research on safety early warning of abnormal A-annular pressure of “three-high” gas wells based on data mining

A major safety accident will be triggered when the A-annular pressure value of high pressure, high productivity and high sulfur gas well exceeded the maximum allowable value. The A-annular pressure value of high pressure high productivity and high sulfur gas well once exceeded the allowable value will trigger a major safety accident. Therefore, this paper proposed a data mining based the gas well early warning strategy by analyzing the annular pressure mechanism and the change in the pattern of instantaneous gas volume, well temperature, and annular pressure in various conditions. To summarize, the law of gas well abnormal A-annular pressure is aimed at constructing a gas well safety warning rule for gas well stable production stage and shutdown period where the initial parameters setting in the early warning rule and adjustment optimization mechanism is also determined. Lastly, with the use of historical abnormal samples, the gas well early warning strategy bought up in this paper was verified. The example shown that compared with the traditional DCS system warning strategy, the gas well safety early warning strategy can identify the abnormal A-annular pressure phenomenon 82 h in advance thus achieving production safety management.

Amplitude variation with offset analysis of nonbright spots for gas channel identification: A case study from the western Sichuan Basin, China

The Shaximiao Formation in the Zhongjiang Gas Field of the Sichuan Basin was initially a high-productivity gas field with the bright spot channel as the vital exploration target. With further development, gas wells were obtained in some nonbright spot areas, which caused interpreters to pay great attention to the channels with nonbright spot abnormal amplitudes. We have developed a method to delineate nonbright spot channels from the complicated sand-mudstone contact relationship. First, we classified sandstone into types I, IIa, IIb, and III, depending on the responses of the amplitude variation with offset from the drilled data, to produce a forward model. We the explain why the hidden channel cannot be identified using the full-angle stack seismic data based on this model. Afterward, we put forward a difference, between the synthetic seismogram responses of bright and nonbright channels, in creating seismic-to-well ties for nonbright channels. This difference from bright channels is that the synthetic data’s wave peak is not corresponding to the peak of the real seismic data. The wave trough has the same situation. Finally, we used far-angle stack seismic data to calculate coherent energy and instantaneous spectral attributes (the latter produced for red-green-blue blending) to identify the hidden channel. We observed that parts of the channel are more clearly visible in the far-angle stack than in the full-angle stack data. In the latter situation, we cannot describe the geometric shape of the channel elaborately. The Shaximiao Formation example is a relatively effective analog for nonbright spot plays compared with elsewhere.

Tight carbonate gas well deliverability evaluation and reasonable production proration analysis

It is very important to accurately predict the gas well productivity and reasonably allocate the gas production at the early development stage of gas reservoirs. However, both the non-Darcy and stress sensitivity effects have not been investigated in dual-porosity model of tight carbonate gas reservoirs. This paper proposed a new dual-porosity binomial deliverability model and single-well production proration numerical model, which consider the effects of non-Darcy and stress sensitivity. The field gas well deliverability tests data validated the accuracy of the new analytical model, which is a very helpful deliverability method when lacking deliverability test. A geological model was built on the results of the well log, well testing, and well production analysis. Then, a reasonable production proration analysis was conducted based on history matched single-well numerical model. The gas productivity index curve and production–prediction of MX22 several simulation cases were adopted to analyze the reasonable production proration. The results indicate that 1/6 may be suitable for high productivity gas well proration. In addition, the absolute open flow rate from the numerical simulation is higher than that from the new deliverability equation, which also shows that the pressure transient analysis sometimes has some deviation in formation property prediction. It is suggested comprehensively utilizing the analytical binomial model and the single-well numerical model in tight carbonate gas well deliverability evaluation.

Delta Sedimentary Model of Shanxi Formation in Qingyang Gas Field, Ordos Basin

Wang, M.; Wu, Z.; Peng, C.; Fan, Q.Q.; Fu, B.; Ouyang, S.K.; Wang, Y.; Wan, D.F., and Yu, X.N., 2020. Delta sedimentary model of Shanxi Formation in Qingyang Gas field, Ordos Basin. In: Guido Aldana, P.A. and Kantamaneni, K. (eds.), Advances in Water Resources, Coastal Management, and Marine Science Technology. Journal of Coastal Research, Special Issue No. 104, pp. 425–434. Coconut Creek (Florida), ISSN 0749-0208.Qingyang gas field is a new exploration tight sandstone gas field in the southwest of Ordos Basin, with characteristics of thin production layer, low physical property of reservoir, Shan 1 member is the main production layer. Based on the analysis of field outcrop observation, core drilling and logging data, the Shan 1 member is divided into three sublayers according to cycle characteristics. Based on stratigraphic division, the sedimentary environment, sediment source and sand body distribution characteristics are defined through mineral petrology analysis, grain size analysis, sedimentary facies marker research and Paleogeomorphology restoration. The controlling factors of high-quality reservoir development were analyzed on the basis of comprehensive sedimentary analysis and structural recovery. During the deposition of the Shan 1 member, the meandering river delta is developed, and the sand body is distributed from southwest to northeast. Four main river channels are developed in the study area. The reservoir is mainly developed in the river bed residence, point bar of delta plain and the mouth bar, underwater distributary channel of delta front. Most of high productivity gas wells are distributed in the updip part of the slope. Sedimentation determines the spatial basis of reservoir formation, structural evolution controlling the migration and accumulation mode and the type of gas reservoir in the stage of hydrocarbon accumulation. The overlapping area of sand body development and the updip part of the slope is the favourable area for the gas reservoir.

Simulation of Gas-Liquid Two-Phase Flow-Induced Corrosion at Premium Connection in High Productivity Gas Wells Containing CO<sub>2</sub>

Numerical simulation was carried out to investigate the gas-liquid two-phase flow-induced corrosion in high productivity gas wells containing carbon dioxide. The Eulerian-Eulerian multiphase model combined with the electrochemical corrosion model was applied to simulate the corrosion rate at the tubing thread connection induced by corrosive medium containing carbon dioxide. The predicted corrosion rate was compared with the field data in the literature. It is shown that the predicted results were conservative when merely considering the phase distribution. Qualitative analysis between the predicted phase distribution, flow characteristics, erosion-corrosion position and the field data was made.

High-productivity gas separation membranes derived from pyromellitic dianhydride and nonlinear diamines

Two new polyimides have been obtained from commercial and inexpensive pyromellitic dianhydride and two affordable meta-substituted diamines bearing ortho methyl substituents (i.e., 2,4,6-trimethyl-1,3-phenylene diamine (TMPD) and 5,7-diamino-1,1,4,6-tetramethylindane (TMID)). Due to a combination of dianhydride rigidity and meta substitution, in addition to the influence of the ortho substituents on the orthogonal placement of the amine and imide planes, the two polyimides exhibited a high fractional free volume and a high rigidity. Therefore, these polyimides were able to produce gas separation membranes with an excellent balance between permeability and selectivity, and these membranes performed similar to many polymers with intrinsic microporosity (PIMs) and surpassed the 1991 Robeson upper bound for all gas pairs. The behavior is more favorable than that for similar polyimides based on 6FDA, which is considered to be the best dianhydride for gas separation polyimides.

Stimulation technologies for Longwangmiao Fm gas reservoirs in the Sichuan Basin and their application results

The Longwangmiao Fm group gas reservoirs in the Moxi structure in central Sichuan Basin feature high temperature, high pressure and high H2S content. The thickness of such high permeable reservoirs with great homogeneity is a geologic basis for a high-productivity gas well, and good match of natural fractures and vugs is the key factor to high well productivity. Overbalance drilling is likely to cause the opening-up of natural fractures, which will lead to the leakage of drilling fluid and severe damage to the reservoir. Experimental evaluation results show that the damage rate of the drilling fluid to the rock sample is between 82.2% and 89.2%, which severely restricts the productivity of gas wells. Therefore, it is necessary to deepen the experimental evaluation technologies and methods to promote the design pertinence of technical parameters. The study shows: first, the optimized gelling acid and steering acid are effective in slowing down speed and removing blockage, forming acidizing wormholes and effectively eliminating the blockage effect caused by drilling liquid pollution; second, the self-developed fiber steering agent and soluble temporary blocking ball can divert the acid, increasing the processing pressure at the well bottom by 5–15 MPa, realizing the even stimulation of heterogeneous reservoirs; third, based on experimental evaluation such as the acid penetration and acid rock reaction, it is recommended that the pumping rate be 3.0–3.5 m3/min in acidizing treatment and the acid intensity for blockage removal be 3.0–5.0 m3/m; fourth, the established blockage removal and steering acidizing technology have been applied in more than 20 wells with a remarkable productivity-increase effect, which gives full play to the natural productivity of gas wells and decreases the acid application scale. All these technologies and measures effectively enhance the development quality and profit of the gas reservoir.

English

Cladding is a surface modification process in which a specially designed alloy is surface welded in order to enhance corrosion resistant properties. Common cladding techniques include Gas Tungsten Arc Welding (GTAW), submerged arc welding (SAW) and gas metal arc welding (GMAW). Because of high reliability, easiness in operation, high penetration good surface finish and high productivity gas metal arc welding became a natural choice for fabrication industries. This paper presents central composite rotatable design with full replication techniques to predict four critical dimensions of bead geometry. The second order regression method was developed to study the correlations. The developed models have been checked for adequacy and significance. The main and interaction effects of process variables and bead geometry were presented in graphical form. Using fmincon function the process parameters were optimized. Key words: Gas metal arc welding (GMAW), weld bead geometry, mathematical model.

Fracture and Gas Potential in Tight Sandstone Reservoirs in the Eastern Part of Sulige Gas Field, Ordos Basin (China)

Sulige gas field in Ordos Basin is the largest discovered gas field in China. But tight sandstone reservoirs is becoming the main limitation of natural gas exploration and exploitation in Sulige gas field. Intensively analysis on micro-pore structure of sandstone reservoirs in Shan1 member of Shanxi formation and He8 member of Shihexizi formation in Permian system in the eastern part of Sulige gas field are conducted by means of drill core observation, slice identification, SEM analysis, casting slice and mercury injection etc. analytical methods. Result shows that fracture is well developed in sandstone reservoirs in the northern part of the interest area, by which petrophysical property of tight sandstone reservoir is improved distinctly. Types of fracture are dominated by diaclase and the diagenesis cracks. Main direction of the fractures is NE and NW, and the angle of the two groups fractures is nearly 90°.But one set of the conjugate shear fractures would develop well and the other was rest rained by the influenced of strong anisotropism of sandbodies. Diaclase and the diagenesis cracks developed along the boundery of tectonic divisions. Fracture is one of the important reasons for improvement of permeability in tight sandstone reservoirs. Gas potential of sandstone in fracture-developed section is much better than that of non-fracture section. Consequently, it is signaficant for all of reservoir forecasting, high productivity gas pool seeking, design and construction of natural gas exploitation to grasp distribution laws of fracture.

Production Simulate Analysis of Multiple-Fractured Horizontal Gas Wells

Productivity simulation of multiple-fractured horizontal wells is the core technique during optimizing fracture’s amount and parameters. According to the dissymmetric double wings of multiple fractured high productivity horizontal gas well which is equality discreted, applying the theory of point source, the formula of unsteady seepage of gas and the principle of superposition, this paper deduce the model of overall pressure drop in formation considering the mutual interference of multi fracture. Besides, considering the high velocity non-Darcy’s flow’s effect to the fracture productivity in high horizontal gas well, establishing a more sophisticated new model to stimulate the fracture productivity in horizontal gas well. Via stimulation calculating and comparative analysing the high velocity non-Darcy’s flow, the dissymmetry of the double wings fracture, the length of fracture and the conductivity’s effect on the multiple fracture gas well’s productivity. This offers a more accurate method to optimizing the fracture’s amount in landscape and the parameters of fracture in high productivity gas well and making sure the proper production’s differential pressure.

ESTIMATION OF QUALITY FACTOR Q FROM THE INSTANTANEOUS FREQUENCY AT THE ENVELOPE PEAK OF A SEISMIC SIGNAL

In this paper, we derive an approximate equation combining the quality factor Q, the travel time of a wave, and the variation of the instantaneous frequency (IF) at the envelope peaks of two successive seismic wavelets, along the wave-propagating direction, based on the theory of one-way wave propagation in a 1D viscoelastic medium. We then propose a method (called the WEPIF method) to estimate Q by measuring the variations of the wavelet envelope peak IF (WEPIF) with the travel time of seismic wavelet. For zero-offset VSP data and poststack seismic data, we describe how to implement the WEPIF method in detail. A test on synthetic VSP data shows that the WEPIF method is less sensitive to interference from the reflector than the logarithm spectral ratio and the centroid frequency shift methods. Applied to field VSP data, the WEPIF method gives a Q-curve with nearly the same distribution as the results from a known well. Applied to poststack seismic data, it produces a Q-profile that indicates an intense absorption zone corresponding to the excellent gas-bearing reservoir. This allows us to predict a potential high-productivity gas well. Drilling confirmed this prediction. The WEPIF method can be applied to poststack seismic data and zero-offset VSP data.

Overview: Gas Production Technology (November 2007)

For this feature, I have chosen three excellent papers that highlight the complex, but very common tendency of gas wells to "load up." Given the explosive growth in new low-rate gas completions and the persistent move of all older high-rate completions toward the same condition, this topic seemed fit for a little more attention. Although not specifically addressed in these papers, the recent widespread use of very long (or thick), multihydraulically fractured completions intensifies these problems. If you think you do not have a well with a liquid-loading issue, you probably have not looked hard enough. Each of these papers addresses the issue from a different viewpoint. One uses video logging to "see" what is happening downhole, while another uses truly remarkable integrated transient wellbore and reservoir-simulation tools to predict mathematically the same behaviors observed in the first. The other paper stakes out a middle position of using comparatively simple analytical models to predict the exact location of a standing liquid level within a gas-producing section. The video-logging paper describes a series of production logs run in several horizontal wells. In the best spirit of data collection and research, the results were far from the expected outcome and revealed the predrill assumption of no potential loading problems to be incorrect. Also, the authors specifically put to rest that long-debated question of what happens to liquid and solids accumulations in horizontal wells with a toe-up trajectory. The paper on modeling the liquid-loading process builds on and complements N. Dousi et al. 2006 "Numerical and Analytical Modeling of the Gas-Well Liquid-Loading Process" [SPE Production & Operations21(4): 475–482 (SPE 95282-PA)]. In both papers, water loading up the wellbore is studied in detail. They both predict a "metastable" flow condition in wells that cannot lift all the liquid but have sufficient liquid injectivity (into the producing zones) to not die completely. This wellbore condition is now attributed to significant formation damage and well-performance deterioration after shut-in periods. The integrated-wellbore/reservoir-model paper takes the subject even further, with an exhaustive transient mathematical treatment of the loadup process. Coupling a reservoir simulator with a time-dependent wellbore model, the authors were able to prove that mathematical models can match an erratic production profile, although that is rarely the objective of the typical modeler. Whatever your mathematical inclination, one of these offerings should help you gain a greater appreciation of the complex process of liquid loadup in wellbores. Gas Production Technology additional reading available at the SPE eLibrary: www.spe.org SPE 107870 "Analysis of Condensate Buildup and Flow Impairment of Retrograde Gases in Fissured Reservoirs" by H. Ayala, Pennsylvania State University, et al. SPE 107169 "Controls on Water Cresting in High-Productivity Horizontal Gas Wells" by R.P. Sech, SPE, Imperial College London, et al. SPE 107274 "Economic Viability of Gas-to-Liquid Technology" by Ali A. Garrouch, SPE, Kuwait University SPE 101497 "Applications of Acoustic Liquid-Level Measurements in Gas Wells" by J.N. McCoy, Echometer Company, et al.