An Integrated Experimental Workflow for Formation Water Characterization in Shale Reservoirs: A Case Study of the Bazhenov Formation

SPE Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Ekaterina S. Kazak ◽  
Andrey V. Kazak ◽  
Felix Bilek
Keyword(s):  
Isotopic Composition ◽  
Bound Water ◽  
Clay Content ◽  
Isotopic Analysis ◽  
Well Logs ◽  
Formation Water ◽  
Laboratory Methods ◽  
Rock Samples ◽  
Water Origin ◽  
Shale Reservoirs

Summary In this study, we aim to develop a new integrated solution for determining the formation water content and salinity for petrophysical characterization. The workflow includes three core components: the evaporation method (EM) with isotopic analysis, analysis of aqueous extracts, and cation exchange capacity (CEC) study. The EM serves to quickly and accurately measure the contents of both free and loosely clay-bound water. The isotopic composition confirms the origin and genesis of the formation water. Chemical analysis of aqueous extracts gives the lower limit of sodium chloride (NaCl) salinity. The CEC describes rock-fluid interactions. The workflow is applicable for tight reservoir rock samples, including shales and source rocks. A representative collection of rock samples is formed based on the petrophysical interpretation of well logs from a complex source rock of the Bazhenov Formation (BF; Western Siberia, Russia). The EM employs the retort principle but delivers much more accurate and reliable results. The suite of auxiliary laboratory methods includes derivatography, Rock-Eval pyrolysis, and X-ray diffraction (XRD) analysis. Water extracts from the rock samples at natural humidity deliver a lower bound for mineralization (salinity) of formation water. Isotopic analysis of the evaporated water samples covered δ18O and δ2H. A modified alcoholic ammonium chloride [(NH4Cl)Alc] method provides the CEC and exchangeable cation concentration of the rock samples with low carbonate content. The studied rock samples had residual formation water up to 4.3 wt%, including free up to 3.9 wt% and loosely clay-bound water up to 0.96 wt%. The latter correlates well to the clay content. The estimated formation water salinity reached tens of grams per liter. At the same time, the isotopic composition confirmed the formation genesis at high depth and generally matched with that of the region's deep stratal waters. The content of chemically bound water reached 6.40 wt% and exceeded both free and loosely bound water contents. The analysis of isotopic composition proved the formation water origin. The CEC fell in the range of 1.5 to 4.73 cmol/kg and depended on the clay content. In this study, we take a qualitative step toward quantifying formation water in shale reservoirs. The research effort delivered an integrated workflow for reliable determination of formation water content, salinity lower bound, and water origin. The results fill the knowledge gaps in the petrophysical interpretation of well logs and general reservoir characterization and reserve estimation. The research novelty uses a unique suite of laboratory methods adapted for tight shale rocks holding less than 1 wt% of water.

Comprehensive Studies of Formation Water for Achimov and Bazhenov Formations — Revitalizing Archived and Old Cores

2021 ◽  
Author(s):  
Ekaterina Sergeevna Kazak ◽  
Andrey Vladimirovich Kazak
Keyword(s):  
Pore Water ◽  
Bound Water ◽  
Water Salinity ◽  
Core Material ◽  
Composition Analysis ◽  
Low Permeability ◽  
Formation Water ◽  
Laboratory Studies ◽  
Rock Samples ◽  
Pore Water Salinity

Abstract The sediments of Bazhenov (BF) and Achimov (ACh) formations have been studied for more than 50 years, and to date, a large amount of core material obtained during drilling at the stage of exploration is stored in the core stores of Russian industrial companies. The rise in the cost of the complex of geological exploration and the emergence of new research methods enabled studies of the old/dry core from previously drilled exploration wells. BF and ACh reservoir rocks have low permeability and initially low water saturation, and therefore, during storage, rock samples could partially retain pore water. To study its composition and quantitative content, we used the previously proposed integrated approach with proven effectiveness in fresh low-permeability BF rocks. The studied materials include BF rock samples from 3 different fields stored for 2 years after sampling in the laboratory, and ACh rock samples from 12 fields, cored more than 10 years ago at the geologic exploration stage. The complex technique includes determining free and bound water contents by the evaporation method with isotopic analysis (δ18O and δD) of the released water. The modified water extraction method provides a range of pore water salinity, while the modified alcohol ammonium chloride method measures the cation exchange capacity (CEC). Auxilary methods include Rock-Eval pyrolysis to determine organic matter content, X-ray diffraction analysis (XRD) to assess the mineral composition of sediments. The verification of the results for the BF rock samples was carried out according to the data obtained for the new/fresh core, while for the ACh rock samples — according to the results of the direct chemical composition analysis of the formation water. Despite the low permeability, we found that the BF and ACh rock samples during storage lost almost all (up to 90%) free water due to evaporation. At the same time, salts from formation water remained in the pore space, which made it possible to estimate the range of its NaCl salinity: 1.84–14.7 g/L for ACh rock samples and 4.49–20.19 g/L for BF rock samples. The obtained values set the lower limit of the possible pore water salinity of the studied ACh and BF rock samples. Moreover, the results match those from direct salinity measurements in the ACh depth intervals and the results of fresh BF core laboratory studies. We showed that the old/dry BF and ACh core could be effectively used to assess the bound water content with subsequent determination of its genesis from isotopic composition data and CEC measurements. This opportunity relies on the high clay content in the studied BF and ACh rock samples. The obtained results show the fundamental capability of informative laboratory studies of BF and ACh rock samples from public and private core storage facilities and give new life to archived and old/dry core.

Formation Water Characterization of the Shale Reservoir Rocks Using Integrated Workflow

2020 ◽  
Author(s):  
Ekaterina Kazak ◽  
Andrey Kazak ◽  
Felix Bilek
Keyword(s):  
Isotopic Composition ◽  
Water Content ◽  
Pore Water ◽  
Bound Water ◽  
West Siberia ◽  
Exchange Capacity ◽  
Formation Water ◽  
Reservoir Rocks ◽  
Water Extracts

<p>The paper presents the results of a novel integrated solution of formation water content and salinity determination of the low permeability reservoir rock of Bazhenov formation (West Siberia, Russia) for petrophysical characterization. The workflow is based on three techniques: evaporation method (EM) with isotopic composition analysis, analysis of water extracts, and cation exchange capacity (CEC) study. The EM offers a fast, efficient, and accurate measurement of the residual water content with breakdown to free and loosely clay-bound types. The isotopic composition reveals the origin and genesis of pore water. The chemical analysis of water extracts delivers a lower bound salinity in terms of NaCl. CEC describes rock-fluid interactions. The two methods of cation exchange capacity (CEC) measurement were applied – alcoholic NH<sub>4</sub>Cl ((NH<sub>4</sub>Cl)Alc) and hexammnninecobalt(III) chloride (CoHex) method. Both showed similar results. CEC varies from 2.87 to 5.82 meq/kg by ((NH<sub>4</sub>Cl)Alc method and from 2.87 to 6.38 cmol/kg by CoHex method and depends on the clay content. Ca, Na, Mg, K form exchange complex of all studied core samples. According to interrelation (rNa+rK)>rCa the exchange complex type is marine and was inherited from the composition of the paleobasin seawater.</p><p>The target rock samples contained the residual formation water 0.11–4.27 wt.%, including free 0.04–3.92 wt.% and loosely clay-bound water 0.09–0.96 wt.%. The loosely bound water content correlates well to the clay mineral fraction. The amount of chemically bound water fell in a range of 0–6.40 wt.% and exceeds that of free and loosely bound water.</p><p>We found that water extract composition depends on the core mineral content, except chlorine and bromine, which originates from the pore water. Using the thermodynamic modelling in PHREEQC program, next ratio of cations in pore water was found - Na (up to 91%), Mg (up to 5.6%), Ca (up to 2.6 %) and K (up to 0.8%). According to the calculation using the water extracts results, the pore water salinity as NaCl changes from 1.23 to 21.96 g/L. The corresponding isotopic composition indicated the deep formation genesis and generally correlated to that of the deep stratal waters of the West Siberia. Isotopic composition proved the formation origin of extracted pore water samples.</p><p>The study made a qualitative step up towards the quantitative characterization of formation water in shale reservoir rocks with the initial water content of less than 1 wt.%.</p><p><span>This work was supported by the Russian Science Foundation (grant No. 17-77-20120).</span></p>

Isotopic composition analysis of dissolved mercury in seawater with purge and trap preconcentration and a modified Hg introduction device for MC-ICP-MS

2015 ◽  
Vol 30 (2) ◽  
pp. 353-359 ◽  
Author(s):  
Haiying Lin ◽  
Dongxing Yuan ◽  
Bingyan Lu ◽  
Shuyuan Huang ◽  
Lumin Sun ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Isotopic Analysis ◽  
Composition Analysis ◽  
Analysis Method ◽  
Purge And Trap ◽  
Icp Ms ◽  
Dissolved Mercury ◽  
Preconcentration Method

A modified introduction device and a preconcentration method were developed to enhance the sensitivity of the Hg isotopic analysis method.

RADIOACTIVITY ANALYSES OF OIL WELL SAMPLES

Geophysics ◽  
1942 ◽  
Vol 7 (1) ◽  
pp. 90-94 ◽  
Author(s):  
Bruno Pontecorvo
Keyword(s):  
Laboratory Tests ◽  
Laboratory Method ◽  
Well Logs ◽  
Oil Well ◽  
Rock Samples

A laboratory method of analyzing the radioactivity of rock samples is described in which the laboratory tests are designed to simulate the conditions which prevail when radioactivity logs of wells are made. Thus the radioactivity of samples may be correlated with the results of such well logs and their interpretation improved thereby.

Petrophysical Type Curves for Identifying the Electrical Character of Petroleum Reservoirs

2007 ◽  
Vol 10 (06) ◽  
pp. 711-729 ◽  
Author(s):  
Paul Francis Worthington
Keyword(s):  
Water Saturation ◽  
Early Stage ◽  
Well Logs ◽  
Log Analysis ◽  
Well Log ◽  
Formation Water ◽  
Water Conductivity ◽  
Core Data ◽  
Water Saturated ◽  
Petrophysical Evaluation

Summary A user-friendly type chart has been constructed as an aid to the evaluation of water saturation from well logs. It provides a basis for the inter-reservoir comparison of electrical character in terms of adherence to, or departures from, Archie conditions in the presence of significant shaliness and/or low formation-water salinity. Therefore, it constitutes an analog facility. The deliverables include reservoir classification to guide well-log analysis, a protocol for optimizing the acquisition of special core data in support of log analysis, and reservoir characterization in terms of an (analog) porosity exponent and saturation exponent. The type chart describes a continuum of electrical behavior for both water and hydrocarbon zones. This is important because some reservoir rocks can conform to Archie conditions in the fully water-saturated state, but show pronounced departures from Archie conditions in the partially water-saturated state. In this respect, the chart is an extension of earlier approaches that were restricted to the water zone. This extension is achieved by adopting a generalized geometric factor—the ratio of water conductivity to formation conductivity—regardless of the degree of hydrocarbon saturation. The type chart relates a normalized form of this geometric factor to formation-water conductivity, a "shale" conductivity term, and (irreducible) water saturation. The chart has been validated using core data from comprehensively studied reservoirs. A workflow details the application of the type chart to core and/or log data. The analog role of the chart is illustrated for reservoir units that show different levels of non-Archie effects. The application of the method should take rock types, scale effects, the degree of core sampling, and net reservoir criteria into account. The principal benefit is a reduced uncertainty in the choice of a procedure for the petrophysical evaluation of water saturation, especially at an early stage in the appraisal/development process, when adequate characterizing data may not be available. Introduction One of the ever-present problems in petrophysics is how to carry out a meaningful evaluation of well logs in situations where characterizing information from quality-assured core analysis is either unavailable or is insufficient to satisfactorily support the log interpretation. This problem is especially pertinent at an early stage in the life of a field, when reservoir data are relatively sparse. Data shortfalls could be mitigated if there was a means of identifying petrophysical analogs of reservoir character, so that the broader experience of the hydrocarbon industry could be utilized in constructing reservoir models and thence be brought to bear on current appraisal and development decisions. Here, a principal requirement calls for type charts of petrophysical character, on which data from different reservoirs can be plotted and compared, as a basis for aligning approaches to future data acquisition and interpretation. This need manifests itself strongly in the petrophysical evaluation of water saturation, a process that traditionally uses the electrical properties of a reservoir rock to deliver key building blocks for an integrated reservoir model. The solution to this problem calls for an analog facility through which the electrical character of a subject reservoir can be compared with others that have been more comprehensively studied. In this way, the degree of confidence in log-derived water saturation might be reinforced. At the limit, the log analyst needs a reference basis for recourse to capillary pressure data in cases where the well-log evaluation of water saturation turns out to be prohibitively uncertain.

scholarly journals Estimates of land and sea moisture contributions to the monsoonal rain over Kolkata, deduced based on isotopic analysis of rainwater

2017 ◽  
Vol 8 (2) ◽  
pp. 313-321 ◽  
Author(s):  
Shaakir Shabir Dar ◽  
Prosenjit Ghosh
Keyword(s):  
Isotopic Composition ◽  
Arabian Sea ◽  
Trajectory Analysis ◽  
Gordon Equation ◽  
Isotopic Analysis ◽  
Southwest Monsoon ◽  
Oceanic Water ◽  
Isotopic Data ◽  
Fractionation Model ◽  
Land Mass

Abstract. Moisture sources responsible for rains over Kolkata during the summer monsoon can be traced using backward air-mass trajectory analysis. A summary of such trajectories between June and September suggest that these moisture parcels originate from the Arabian Sea and travel over the dry continental region and over the Bay of Bengal (BoB) prior to their arrival at Kolkata. We use monthly satellite and ground-based observations of the hydrometeorological variables together with isotopic data of rainwater from Bangalore and Kakinada to quantify the contributions of advected continental and oceanic water vapour in the Kolkata rains. The vapour mass is modified during its transit from its original isotopic value due to addition of evaporated moisture from the BoB, and further modification occurs due to the process of rainout during transport. The evaporated component is estimated using the Craig–Gordon equation. The rainout process is simulated using a Rayleigh fractionation model. In this simulation we assume that the initial isotopic composition of vapour originating from the continent is similar to the rainwater composition measured at Bangalore. In order to explain the monthly isotopic composition in southwest monsoon rainwater at Kolkata, we invoke 65–75 % moisture contribution from the BoB; the remaining moisture is from the continental land mass.

High-precision isotopic analysis of Cu in blood serum via multi-collector ICP-mass spectrometry for clinical investigation: steps towards improved robustness and higher sample throughput

2017 ◽  
Vol 32 (3) ◽  
pp. 597-608 ◽  
Author(s):  
Sara Lauwens ◽  
Marta Costas-Rodríguez ◽  
Hans Van Vlierberghe ◽  
Frank Vanhaecke
Keyword(s):  
Mass Spectrometry ◽  
Isotopic Composition ◽  
Blood Serum ◽  
Diurnal Variation ◽  
Clinical Investigation ◽  
Isotopic Analysis ◽  
Clinical Context ◽  
Sample Throughput ◽  
Icp Ms ◽  
Icp Mass Spectrometry

A procedure for Cu isolation from serum prior to MC-ICP-MS measurements was developed and applied in a clinical context. The serum Cu isotopic composition does not show diurnal variation.

Precise boron isotopic analysis of natural rock samples using a boron-mannitol complex

1992 ◽  
Vol 94 (3) ◽  
pp. 193-204 ◽  
Author(s):  
Eizo Nakamura ◽  
Tsuyoshi Ishikawa ◽  
Jean-Luis Birck ◽  
Claude J. Allègre
Keyword(s):  
Isotopic Analysis ◽  
Rock Samples ◽  
Natural Rock
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