Jingbian Gas Field Research Articles

Application of Reservoir Blockage-relieving in Low Permeability Carbonate of Jingbian Gas-field

Abstract Jingbian gas-field is a low-permeability and lithological gas reservoir with strong reservoir heterogeneity and poorly physical properties. As the gas-field is getting older and older, its gas wells start to produce less, and have growing difficulties to lift water and finally fail to work normally and steadily. One inborn factor lies in the unstable liquid composition of Jingbian gas-field: salty formation water with easy-fouling ions and acidic gas such as CO2 and H2S. Living in the underground for a long time these active materials prone to make the forming of water blocking and the solid deposition, which will weaken gas flow ability and threaten the production. After a detailed study on the plugging, there are three kinds of blocking divided: abruptly impurity blocking, slowly water locking, and energy deficiency. To relieve these blocking, methods have been put forth and carried out in field with achievement. The successful application has brought blockage gas wells solutions in Jingbian gas-field.

Optimization of Velocity String Drainage and Gas Recovery Process for Sour Gas Wells in Jingbian Gas Field

Abstract In view of the gradual attenuation of gas well energy during the development of Jingbian gas field, the liquid carrying effect of some gas wells with small gas production becomes worse, the drainage effect of 60 % gas wells is not ideal, and the H2S content of the lower paleo-sulfur gas wells is high, the salinity is high, there is a certain corrosion, and most of the drainage measures cannot be implemented. The optimization of sulfur-resistant velocity string was carried out from the aspects of velocity string size and pipe material, and the appropriate pipe diameter and pipe material were selected. A new type of broken disc speed string plug was developed, which successfully solved the problem that the existing plug could not be broken or returned after construction. The field application results show that compared with the 27/8 “ string, the liquid carrying flow rate is reduced by 82 %. After 2.5 years of service, the anti-corrosion performance of the pipe is good. The cumulative increase of the well is 445.4 thousand cubic meters, and the effective rate of the measures is 97.45 %. The stable and continuous liquid carrying of the gas well is realized, which has a good application effect. It has certain reference significance for the implementation of the drainage gas recovery technology of the velocity string in the lower ancient sulfur gas well.

Mechanisms Underlying the Bromine Anomaly in the Brine of the Jingbian Gas Field, Ordos Basin, Northwestern China

Mechanisms Underlying the Bromine Anomaly in the Brine of the Jingbian Gas Field, Ordos Basin, Northwestern China

Optimization of Anti-freezing and Unblocking Measures for Natural Gas Wells and Pipelines: A Case from the Gaoqiao Area of Jingbian Gas Field, Ordos Basin

Optimization of Anti-freezing and Unblocking Measures for Natural Gas Wells and Pipelines: A Case from the Gaoqiao Area of Jingbian Gas Field, Ordos Basin

Comparison and adaptability evaluation of formation pressure calculation methods and computer simulation in Jingbian gas field

In the process of oilfield development, formation pressure is an essential parameter for evaluating oilfield development effect, calculating dynamic geological reserves, conducting daily dynamic analysis of oil and water Wells and predicting oilfield performance. The pressure recovery time of conventional gas well after shut-in is very long, and it is difficult to effectively carry out targeted implementation due to the influence of gas field external supply task. In this paper, based on the actual data of Jingbian gas field, through the comparison of several calculation methods of formation pressure, the best method to calculate formation pressure is comprehensively screened out. The results show that: ①For a single method, the accuracy of the method from high to low is the well head casing pressure conversion method, the pressure drop curve method, the binomial productivity equation method, and the quasi-steady state mathematical model method.②The absolute error of multi-method comprehensive calculation method is 0.9MPa, which is far less than the average absolute error directly calculated by one method. The multi-method comprehensive calculation method is reliable when applied to the formation pressure evaluation of typical gas Wells in Jingbian gas field, which lacks data.

Comparative Study on the Reservoir Characteristics and Development Technologies of Two Typical Karst Weathering-Crust Carbonate Gas Reservoirs in China

Carbonate reservoirs are the main reservoir types in China, which occupy the large ratio of reserves and production at present. The high-efficiency development of carbonate reservoirs is of great significance to assure the stability of national energy supply. The Lower Paleozoic reservoir in Jingbian gas field and the Sinian reservoir in Anyue gas field are two typical carbonate gas reservoirs, and their successful development experiences can provide significant references for other similar carbonate gas reservoirs. For Jingbian gas field, it is a lithological-stratigraphic reservoir developed in a westward monocline and multiple rows of nose-fold structures, and is a stable craton basin with simple palaeognomy distribution and stable connectivity, which has complex gas-water distribution. However, for Anyue gas field, it is a lithological-structural reservoir with multiple tectonic high points and multiple fault systems, and is biological dune beach facies under extensional setting with highly differentiated inside of the block in palaeognomy characteristics, which has limited connectivity and tectonic side water is in a local area. The difference of gas reservoir characteristics leads to the diverse development strategies. For these two gas reservoirs, although there are some similar aspects, such as the screen of enrichment areas, the application of irregular well pattern and reservoir stimulation techniques, the criteria of enrichment areas, the well types, and the means of reservoir stimulation are absolutely different. In addition, due to the differences of control reserves and production capacity for these two kinds of reservoirs, the mode of stable production is also different. The effective development of Jingbian gas field can give some references to the future exploitation on the Sinian gas reservoir. Firstly, the sedimentary characteristics should be studied comprehensively. Secondly, the distribution pattern and distribution characteristics of the palaeognomy should be found and determined. Thirdly, the distribution of fracture system in the reservoir should be depicted finely. Finally, dynamic monitoring on the production performance should be strengthened, and the management for this gas field should be improved further. The findings of this study can help for better understanding of the Karst weathering-crust carbonate gas reservoir formation characteristics and the optimal development technologies that should be taken in practice.

Research on Main Controlling Factors of Fracturing Reformation of Ancient Sandstone Horizontal Wells in Jingbian Gas Field

From 2015 to 2019, a total of 7 wells in the Shan 28 well area of the Jingbian gas field used pumped bridge plug staged fracturing technology. The average test gas daily gas production rate is 8.13×104m3/d, and the average unblocked flow rate is 46.06×104m3/d, Demonstrating the superiority of the staged fracturing reconstruction process of pumping bridge plugs, However, due to the short time of using the pumped bridge plug staged fracturing process, the main controlling factors of fracturing reformation are not clear, resulting in a large gap between the gas production effect of the reformed well and the expected. Therefore, based on the site construction parameters, this paper uses single factor analysis and grey correlation analysis methods to determine the main control factors for fracturing reformation of the ancient sandstone horizontal well in the Jingbian gas field. Research shows that the length of gas layer, liquid type, average sand ratio, and sand volume are the main factors affecting the open flow and daily gas production of horizontal wells. The research results in this paper have certain guiding significance for the effective development of ancient sandstone horizontal wells.

Minerals Filling in Anhydrite Dissolution Pores and Their Origins in the Ordovician Majiagou Formation of the Southeastern Ordos Basin, China

Mold pore cementation is the key factor constraining the reservoir property in the study area. The anhydrite dissolution pores in the Ordovician Majiagou Formation of southeastern Ordos Basin are commonly filled by minerals such as dolomite, calcite, pyrite, and quartz accounting for more than 90% of the total molds resulting in significant porosity volume reduction. The anhydrite dissolution pores in the Jingbian Gas Field in the middle east of the basin, however, are rarely filled by minerals with more than 30% molds, remaining open to become good reservoir space. Studies reveal that the calcite filling in anhydrite dissolution pores has a relatively negative δ18O value (-15.58‰~-8.96‰ VPDB) and negative δ13C value (-7.56‰~0.26‰ VPDB), which is interpreted to be caused by thermochemical sulfate reduction (TSR). The higher homogenization temperatures (140-234°C) and high salinity (19.13-23.18 wt.% NaCl equivalent) of the primary inclusions in calcite confirm the above interpretation. Dolomite is the second most abundant carbonate formed as by-product of TSR, which is promoted by the precipitation of calcite and resulted enriched in Mg2+/Ca2+ ratio in the pore water. Pyrite forms by the reaction of H2S released from TSR with the Fe2+ in the horizon, which is supported by its cubic habit and relatively high δ34S value (10.50‰~24.00‰VCDT). Quartz with relatively high homogenization temperature (113-154°C) is considered to precipitate in low-pH solution from calcite and pyrite precipitation after TSR. The southeastern Ordos Basin is much lower than the Jingbian Gas Field in paleogeographic location, which is submerged in the sea water of marine phreatic environments for a long time when sea water flooded from the southeastern direction. TSR occurs due to calcium sulfate enriched in pore water resulting in the minerals of dolomite, calcite, pyrite, and quartz filling in the molds leading to the low porosity and permeability of the study area.

Investigation of Productivity Prediction Method for Horizontal Wells in Gas Reservoirs with Closed Bottom and Top Boundaries

This study aims to predict the productivity of an open-hole horizontal gas well (OHHGW) in a gas reservoir with closed bottom and top boundaries (GRCBTBs). First, according to the theory of mirror imaging, an OHHGW in GRCBTBs is transformed into an infinite well array in infinite formation. Second, based on conformal transformation principle, the infinite well array is transformed into two production and two injection wells in the complex plane. Finally, according to the superposition principle of potential, a new productivity prediction method, which is suitable for the horizontal well in GRCBTBs, was developed. The field measured data of Jingbian gas field of Ordos Basin demonstrate the ability of the method to accurately predict the productivity of the OHHGW in GRCBTBs, and the prediction relative error of absolute open flow of well Longping 1 is only 1.03%, that is to say that the method proposed in this study has a certain guiding significance for the development of horizontal wells in GRCBTBs.

Sedimentary and diagenetic facies of tidal flat in epeiric sea and its related descriptive method-a case of Ma51-4 submember in Jingbian gas field of Ordos basin, China

The Ma51-4 submembers of Jingbian gas field in Ordos basin of China belongs to epeiric sea evaporative carbonate tidal flat facies. Supratidal zone of gypsum nodule dolostone and upper part of intertidal zone of gypsum crystal dolostone are most favorable reservoir. The carbonate rocks of Ma51-4 had undergone complex diagenesis. Penecontem-poraneous dolomitization and gypsification provided the material foundation of the reservoir. Epidiagenesis selective dissolution of gypseous dolostone constructs the origin shape of pore structure. The dissolution and filling of various minerals in the burial period determine whether the early dissolution pores can be preserved, and the final state of the reservoir. Burial dissolution and filling of various minerals determined the preservation of early dissolved pores and the final condition of the reservoir. The concept of “minus cement porosity” directly reflects that sedimentary facies have great influence on the growth of reservoir in Ma51-4. Combined with sedimentary microfacies and diagenetic facies, a concise numerical symbol is used to express semiquantitatively sed-imentary microfacies and diagenesis facies. This descriptive method has great benefit in reservoir evaluation and prediction.

Diagenetic Evolution of the Ordovician Ma51+2 Sub-Member Reservoir in the Southern Jingbian Gasfield, Ordos Basin

Diagenetic Evolution of the Ordovician Ma51+2 Sub-Member Reservoir in the Southern Jingbian Gasfield, Ordos Basin

Anomalies and genetic mechanism of ethane carbon isotope in the Ordovician carbonate reservoirs in the Jingbian gas field, Ordos Basin, China

The Ordos Basin is one of the most petroliferous basins in China, and the cumulative gas yield of the Jingbian gas field was 91.36 × 109 m3, accounting for nearly 30% of total gas production in the Ordos Basin. The ethane carbon isotopic value of gases in the Ordovician carbonate reservoirs in the Jingbian gas field is abnormally depleted (δ13C1 > δ13C2 < δ13C3), which has directly led to the controversy over the source and genetic types of natural gas in the Jingbian gas field. To find out the genetic mechanism of anomalies of ethane carbon isotope, components and carbon isotopic values of natural gas in the Jingbian gas field were measured. On this basis, natural gas components and stable carbon isotopic values of the Wushenqi and Jingbian gas field were comprehensively measured and compared. The results show that higher thermal maturity leads to further cracking of the oil generated earlier and the residual kerogen. These secondary cracked gases mixed with the early generated gases lead to the anomalies of ethane carbon isotope. When thermal maturity reaches a critical value, it will have different effect on carbon isotopic values of methane and ethane. The carbon isotopic value of methane will continue to increase; however, that of the ethane will gradually decrease, which will eventually lead to the anomalies of ethane carbon isotope. Migration fractionation will also lead to the abnormally depleted of carbon isotopic values of ethane.

Optimization for the cathodic protection system based on numerical simulation

Cathodic protection was one of important method for the corrosion prevention. With the expand of pipeline at Jingbian gas field, the cathodic protection system had been not qualified for the corrosion prevention of pipeline at Jingbian gas field. The results of survey for pipeline in 2018 years suggested that there were less-protection or over-protection for the corrosion prevention of pipeline. In this study, it was simulated by the COMSOL software to clear the regulation of current for pipeline in different cathodic protection area, and learn the overall situation of cathodic protection station in Jingbian gas field. Finally, optimizing the cathodic protection system for improving the effect by cathodic protection and ensuring the safety production.

Geochemical characteristics and reasons for the carbon isotopic reversal of natural gas in the southern Jingbian gas field, Ordos Basin, China

AbstractThe carbon isotope value of ethane in the southern part of the Jingbian gas field is lower than that in the northern part, indicating a carbon isotopic reversal in the southern Jingbian gas field (δ13Cmethane &gt; δ13Cethane). Through comparing the geochemical characteristics of gases in the southern and northern parts of the gas field, the reasons for the carbon isotopic reversal in the southern Jingbian gas field were determined to be high thermal maturity and mixing action. When thermal maturity reaches a critical value, the carbon isotope value of ethane becomes relatively more depleted with thermal maturity. Although the carbon isotope value of methane increases with thermal maturity, the extent is relatively smaller. Finally, the rare phenomenon of δ13Cmethane &gt; δ13Cethane occurs. High thermal maturity leads to the secondary thermal cracking of gases. Mixing of the cracked gases and primary gases also leads to carbon isotopic reversal. Both of the above mechanisms share a common premise, which is high thermal maturity.

Analysis of the causes of tube blocking in Jingbian gas field

A large number of blockage appeared in gas wells and pipeline appeared, which caused plugging, corrosion and the increasing of wellbore pressure difference, and seriously affect the normal production of gas well of problems. In this paper, the water quality over the years and natural gas production of the JB1# well in the Jingbian gas field were analyzed, also include the composition of blockage with the chemical volumetric method (CVM), X-Ray Diffraction (XRD) and x-ray fluorescence (XFS) method. Meanwhile, the blockage powder was leached in simulated acid work solution, and then the leaching solution was analyzed with CVM. The experimental results show that the produced water in the JB1# well has unstable water quality, high salinity, high Cl- content, and low pH value, high H2S and CO2 content in natural gas, so easy to produce corrosion and carbonate scaling. The main component of the blockage is a mixture of corrosion product Fe2O3 and a small amount of CaCO3 scale. The corrosion product Fe2O3 is mainly generated by the mixture of dissolved oxygen, H2S, CO2 and other corrosion effects. The main cause of blockage in the JB1# well is the deposition of Fe2O3 and CaCO3 scales caused by the corrosive effects of dissolved oxygen, H2S and CO2.

Carbon isotope reversal and its relationship with natural gas origins in the Jingbian gas field, Ordos Basin, China

The geochemical characteristics of natural gases from Lower Paleozoic Jingbian gas field are abnormal and the carbon isotope of most natural gases has reversed, which led to a dispute over the source of natural gas in the Lower Paleozoic. The Upper Paleozoic Yulin gas field is adjacent to the Jingbian gas field, but the geochemical characteristics of the Yulin gas field did not appear abnormal. Besides, the ethane carbon isotope of Upper Paleozoic Yulin gas field is much higher than that of Lower Paleozoic Jingbian gas field. In order to identify the reasons for the carbon isotope reversal of natural gas in Lower Paleozoic Jingbian gas field and its relationship with natural gas source, We conducted the components and stable carbon isotopes of natural gas from Upper Paleozoic Yulin gas field and Lower Paleozoic Jingbian gas field. On the basis of these experiments, we compared the natural gas components and carbon isotope of 100 samples from both Upper Paleozoic Yulin gas field and Lower Paleozoic Jingbian gas field. The results indicate that higher maturity will break the conventional rule, when maturity reaches a certain threshold; δ13Cethane value will decrease with maturity. Although δ13Cmethane value will also increase with maturity, the extent will be relatively smaller. This leads to unusual δ13Cmethane > δ13Cethane in the region with higher maturity. In the process of downward migration of coal-derived gas from Carboniferous-Permian coal measures, component fractionation and carbon isotope fractionation might occur, resulting the ethane components and carbon isotope value of Lower Paleozoic less than those of Upper Paleozoic, which will lead to the carbon isotope reversal. The mixing of oil-derived gas and coal-derived gas at different ratios may also lead to the reversal of carbon isotopes. The natural gas types of Jingbian gas field are mainly coal-derived gas generated from Carboniferous-Permian coal measure strata, with a small amount of oil-derived gas generated from Carboniferous-Permian marine-terrigenous limestone.

Geochemical characteristics of natural gases related to Late Paleozoic coal measures in China

By 2013, more than 20 gas fields related to Late Paleozoic coal measures have been discovered in China, primarily distributed in the Bohai Bay, Ordos, Sichuan, and Junggar Basins. The total proven reserve in these gas fields is more than 3200 × 109 m3, accounting for 30.1% of the proven gas reserves in China. After analyzing the molecular compositions, stable carbon isotopes, and helium isotopes of 375 gas samples, genetic types and origins of the natural gas, as well as the secondary alterations it experienced, are discussed in this study. Most of the natural gas related to the Late Paleozoic coal measures are coal-type gas, with some of the gases from the Sichuan Basin and the Jingbian gas field in the Ordos Basin being oil-type gases generated from marine mudstones in the Permian Longtan Formation and marine carbonates in the Ordovician Majiagou Formation, respectively. The equivalent vitrinite reflectance values based on stable carbon isotopes of natural gases vary from 0.8% to 2.5%, indicating the mature to over mature stage. Positive carbon isotope series (δ13C-CH4 < δ13C-C2H6 < δ13C-C3H8) are observed in most gas samples, and carbon isotope reversals occur in the forms of δ13C-CH4 > δ13C-C2H6 and δ13C-CH4 < δ13C-C2H6 > δ13C-C3H8. The form of δ13C-CH4 > δ13C-C2H6 is primarily resulted from the mixing of oil-type gases of different maturities, while the form of δ13C-CH4 < δ13C-C2H6 > δ13C-C3H8 is primarily resulted from the mixing of coal-type gases of different maturities. High concentrations of hydrogen sulfide in natural gas from the Sichuan Basin and the Chenghai gas field in the Bohai Bay Basin are resulted from thermochemical sulfate reduction (TSR), which causes, to some extent, the fractionation of carbon isotopes. By contrast, the fractionation of methane carbon isotopes resulting from the TSR effect is not clear. Carbon dioxide from the Bohai Bay and Junggar Basins is primarily biogenic, generated via the thermal decomposition of organic matter, while that from the Ordos Basin, Sichuan Basin, and Chenghai gas field is generated via the thermal decomposition of carbonates. Carbon dioxide related to the TSR effect has also contributed to the Sichuan Basin and Chenghai gas field.

Geochemical Characteristics and Genesis of Oil-Derived Gas in the Jingbian Gas Field, Ordos Basin, China

The source rocks of natural gas of the Jingbian gas field in Ordos Basin, China, are unclear, and the origin of oil-derived gas is controversial. On the basis of a series of experiments on source rock evaluation, including total organic carbon, Rock-Eval pyrolysis, carbon isotope composition of kerogen, chloroform bitumen A, maceral compositions, and gas chromatograms, we evaluated the hydrocarbon generation potential of the possible source rocks. We also conducted the components and stable carbon isotopes of natural gas and compared geochemical characteristics of natural gas and source rock-adsorbed gas. The results indicate that source rocks from the Lower Permian Taiyuan Formation have some hydrocarbon-generating capability but far less than its proximate Carboniferous and Permian coal measures. Oil-derived gas originated from Lower Permian Taiyuan Formation limestone was expulsed to the Majiagou Formation by coal-derived gas generated from the Carboniferous and Permian coal measures, as indicated by s...

Geochemical characteristics and origin of natural gas in southern Jingbian gas field, Ordos Basin, China

Jingbian gas field is yet the only Lower Paleozoic-hosted large gas field discovered in Ordos Basin. However, much debate still exists regarding the type and main source of natural gas in the Lower Paleozoic units. Previous studies on Jingbian gas field have mainly focused on the central and northern regions, whereas few studies have addressed the southern part. Basing on natural gas components and carbon isotope compositions of 33 gas samples from 28 wells in southern Jingbian gas field, we investigated the main gas source and phenomenon of carbon isotope reversal. The results indicate that natural gas from the Upper Paleozoic and Lower Paleozoic units are all at the high-mature and over-mature stages, with average dryness coefficients (C1/C1-4) of 0.982 and 0.996, respectively. The Upper Paleozoic natural gas primarily comprises coal-derived gas from Carboniferous-Permian units, whereas the composition of the Lower Paleozoic natural gas is mostly a mixture of Upper Paleozoic coal-derived gas with additional oil-type gas produced by Upper Paleozoic marine limestone. The phenomenon of carbon isotope reversal mainly results from downward diffusion and migration of the mixed coal-derived gases; moreover, in the Upper Paleozoic unit, it is also related to secondary cracking.

Accumulation and potential analysis of self-sourced natural gas in the Ordovician Majiagou Formation of Ordos Basin, NW China

Abstract The characteristics of the marine carbonate source rocks and the accumulation and potential of self-sourced natural gas in the Ordovician Majiagou Formation of the Ordos Basin are investigated based on recent exploration by using geochemistry and gas-source correlation methods. Massive source rocks are developed around the salt depression, east of the paleo-uplift in the Ordovician Majiagou Formation during the Caledonian; and the natural gases produced by argillaceous dolomite and dolomitic mudstone are the major contributors of the Ordovician gas field. Besides widespread carbonate weathering crust reservoir, internal grain band dolomite reservoir are also well-developed in the Majiagou Formation, and both can act as favorable reservoirs. The natural gas of the Majiagou Formation is mainly self-sourced oil-type gas generated by in-situ source rock and accumulated near the source area. There is only limited local accumulation of natural gas produced in the upper strata and stored below. The Majiagou Formation around the salt depression has favorable conditions for large scale natural gas generation and accumulation, and has the advantage of collecting large area natural gas of self-generation and self-preservation. The frontier depression areas of the paleo-uplift to the west, north and south of Jingbian gas field are the potential Ordovician exploration targets in the future.