Cluster analysis of geophysical well‐log data in the North Riley unit, Gaines County, Texas

More than 80% of the present-day oil and gas production in the Danish part of the North Sea is extracted from fields with chalk reservoirs of late Cretaceous (Maastrichtian) and early Paleocene (Danian) ages (Fig. 1). Seismic reflection and in- version data play a fundamental role in mapping and characterisation of intra-chalk structures and reservoir properties of the Chalk Group in the North Sea. The aim of seismic inversion is to transform seismic reflection data into quantitative rock properties such as acoustic impedance (AI) that provides information on reservoir properties enabling identification of porosity anomalies that may constitute potential reservoir compartments. Petrophysical analyses of well log data have shown a relationship between AI and porosity. Hence, AI variations can be transformed into porosity variations and used to support detailed interpretations of porous chalk units of possible reservoir quality. This paper presents an example of how the chalk team at the Geological Survey of Denmark and Greenland (GEUS) integrates geological, geophysical and petrophysical information, such as core data, well log data, seismic 3-D reflection and AI data, when assessing the hydrocarbon prospectivity of chalk fields.

Download Full-text

Evaluation of Mud Weight Using Safe Mud Window Concept Based on Well Log Data: A Case Study of Well OP-002 in the North Sumatra Basin Area, Indonesia

RSF Conference Series: Engineering and Technology ◽

10.31098/cset.v1i1.411 ◽

2021 ◽

Vol 1 (1) ◽

pp. 248-266

Author(s):

Aris Buntoro ◽

Basuki Rahmad ◽

Allen Haryanto Lukmana ◽

Dewi Asmorowati

Keyword(s):

Pore Pressure ◽

Shear Failure ◽

Depth Interval ◽

Well Log ◽

Log Data ◽

Window Analysis ◽

The North ◽

Safe Mud Window ◽

Fracture Gradient ◽

North Sumatra

In the drilling operation of well OP-002 which is located in the North Sumatra Basin at a depth interval of 2887 - 3186 m occurred partial loss, and caving at a depth interval of 500 - 1650 m, where the drilling problem is caused by the use of inappropriate mud weight. Safe mud window analysis is carried out by processing well log data to build PPFG (Pore Pressure Fracture Gradient) and 1D Geomechanics model using several calculation methods. Furthermore, the results of the calculation of pore pressure and fracture gradient are validated with well test data from the well OP-002, so the safe mud window can be determined, and can be used as a basis in the analysis of the drilling problems that occur. The optimum mud weight can minimize wellbore instability, with a limit value that must be greater than the collapse pressure, but not exceeding the minimum insitu stress limit. From the results of the mud safe window analysis, it can be concluded that at a depth interval of 500 - 1650 m caving occurs, because the density value used is smaller than the shear failure gradient, and at a depth interval of 1619 - 2829 m, the density value used is greater than Shmin. To overcome this problem, a mud wight with a safe mud window concept is recommended, namely the selection of the optimum mud weight to be used must be greater than the pore pressure and shear failure gradient and does not exceed the minimum horizontal stress and fracture gradient values.

Download Full-text

Fluid salinity and dynamics in the North Sea and Haltenbanken basins derived from well log data

Geological Society London Special Publications ◽

10.1144/gsl.sp.1992.065.01.25 ◽

1992 ◽

Vol 65 (1) ◽

pp. 327-338 ◽

Cited By ~ 2

Author(s):

Kjetil Gran ◽

Knut Bjørlykke ◽

Per Aagaard

Keyword(s):

North Sea ◽

Well Log ◽

Log Data ◽

The North ◽

The North Sea

Download Full-text

Well Log Data Conditioning Using A Rock Physics Modeling Approach: Examples from the Banyu Urip Field, East Java Basin

10.2523/12917-ms ◽

2008 ◽

Author(s):

Shiyu Xu ◽

Soman Chacko

Keyword(s):

Rock Physics ◽

Well Log ◽

Log Data ◽

Modeling Approach ◽

Rock Physics Modeling ◽

Data Conditioning ◽

Physics Modeling

Download Full-text

The petroleum system of Sibolga Basin based on correlation seismic and well log data

10.29118/ipa.1531.07.sg.005 ◽

2018 ◽

Author(s):

B. Syam

Keyword(s):

Petroleum System ◽

Well Log ◽

Log Data

Download Full-text

List of released wells and availability of digital well-log data for Atlantic, Pacific and Alaska OCS regions through December 31, 1985

Open-File Report ◽

10.3133/ofr8648 ◽

1986 ◽

Author(s):

S.E. Prensky

Keyword(s):

Well Log ◽

Log Data

Download Full-text

Wave Propagation Characteristics in Gas Hydrate-Bearing Sediments and Estimation of Hydrate Saturation

Energies ◽

10.3390/en14040804 ◽

2021 ◽

Vol 14 (4) ◽

pp. 804

Author(s):

Lin Liu ◽

Xiumei Zhang ◽

Xiuming Wang

Keyword(s):

Gas Hydrate ◽

Clay Content ◽

Clean Energy ◽

Compressional Wave ◽

Physical Parameters ◽

Well Log ◽

Log Data ◽

Phase Velocities ◽

Hydrate Saturation ◽

Hydrate Bearing Sediments

Natural gas hydrate is a new clean energy source in the 21st century, which has become a research point of the exploration and development technology. Acoustic well logs are one of the most important assets in gas hydrate studies. In this paper, an improved Carcione–Leclaire model is proposed by introducing the expressions of frame bulk modulus, shear modulus and friction coefficient between solid phases. On this basis, the sensitivities of the velocities and attenuations of the first kind of compressional (P1) and shear (S1) waves to relevant physical parameters are explored. In particular, we perform numerical modeling to investigate the effects of frequency, gas hydrate saturation and clay on the phase velocities and attenuations of the above five waves. The analyses demonstrate that, the velocities and attenuations of P1 and S1 are more sensitive to gas hydrate saturation than other parameters. The larger the gas hydrate saturation, the more reliable P1 velocity. Besides, the attenuations of P1 and S1 are more sensitive than velocity to gas hydrate saturation. Further, P1 and S1 are almost nondispersive while their phase velocities increase with the increase of gas hydrate saturation. The second compressional (P2) and shear (S2) waves and the third kind of compressional wave (P3) are dispersive in the seismic band, and the attenuations of them are significant. Moreover, in the case of clay in the solid grain frame, gas hydrate-bearing sediments exhibit lower P1 and S1 velocities. Clay decreases the attenuation of P1, and the attenuations of S1, P2, S2 and P3 exhibit little effect on clay content. We compared the velocity of P1 predicted by the model with the well log data from the Ocean Drilling Program (ODP) Leg 164 Site 995B to verify the applicability of the model. The results of the model agree well with the well log data. Finally, we estimate the hydrate layer at ODP Leg 204 Site 1247B is about 100–130 m below the seafloor, the saturation is between 0–27%, and the average saturation is 7.2%.

Download Full-text