Borehole gravimetry: A review

Ander, Mark E.; Chapin, David A.

doi:10.1190/1.1885954

Cited by 9 publications

(6 citation statements)

References 1 publication

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“…One can also find equation (1) without the free-air component, e.g., Ander and Chapin (1997) and LaFehr and Nabighian (2012). One can also find equation (1) without the free-air component, e.g., Ander and Chapin (1997) and LaFehr and Nabighian (2012).…”

Section: Introductionmentioning

confidence: 97%

“…where σ is density, F is free-air gradient, g is the difference in gravity measurements between the stations with vertical separation z, and G is Newton's gravitational constant. One can also find equation (1) without the free-air component, e.g., Ander and Chapin (1997) and LaFehr and Nabighian (2012). The resulting density is assigned to both measuring stations (both vertical coordinates), which were used to evaluation of one density value.…”

Section: Introductionmentioning

confidence: 99%

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Density function evaluation from borehole gravity meter data – regularized spectral domain deconvolution approach

Karcol

Pašteka

2016

Geophysical Prospecting

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We present a new method of transforming borehole gravity meter data into vertical density logs. This new method is based on the regularized spectral domain deconvolution of density functions. It is a novel alternative to the “classical” approach, which is very sensitive to noise, especially for high‐definition surveys with relatively small sampling steps. The proposed approach responds well to vertical changes of density described by linear and polynomial functions. The model used is a vertical cylinder with large outer radius (flat circular plate) crossed by a synthetic vertical borehole profile. The task is formulated as a minimization problem, and the result is a low‐pass filter (controlled by a regularization parameter) in the spectral domain. This regularized approach is tested on synthetic datasets with noise and gives much more stable solutions than the classical approach based on the infinite Bouguer slab approximation. Next, the tests on real‐world datasets are presented. The properties and presented results make our proposed approach a viable alternative to the other processing methods of borehole gravity meter data based on horizontally layered formations.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Density function evaluation from borehole gravity meter data – regularized spectral domain deconvolution approach

Karcol

Pašteka

2016

Geophysical Prospecting

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“…The BHGM sensor is a tungsten-proof mass at the end of a lever arm with an inclined metal zero-length spring suspension, which allows it to be both linear and sensitive to small changes in gravity. Presently, the sensor can make routine differential gravity measurements to an accuracy of 10-15 μGal without instrumental errors and, with care in correcting for both instrumental and external errors, down to 1 to 5 μGal (Ander & Chapin, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Borehole gravity measurements are a direct measurement of the bulk density of the surrounding formations. Gravity measurements along a borehole can be used to obtain a gravity difference between two adjacent stations which is a direct measurement of the density of the intervening layer (Ander & Chapin, 1997). The BHGM can be described simply as a deep‐investigating density logging tool.…”

Section: Introductionmentioning

confidence: 99%

MEMS‐based 3‐C borehole gravimeter development

et al. 2023

Geophysical Prospecting

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A micro-electro-mechanical-based 3-C borehole gravimeter has been developed in China for mineral and hydrocarbon exploration. The 3-C borehole gravimeter is composed of a three-axis gravity sensor chip based on a deep silicon etching technique, high-precision capacitive displacement sensing and weak signal detection circuitry.The gravity-sensing chip is a silicon-based integrated spring-mass block system. Silicon wafer is etched by the micro-nanofabrication technique to form a high collimation groove. The size of the gravity-detecting mass block in the sensitive element plays a decisive role in the thermal noise level of the instrument. Deep silicon processing technique can produce a thicker silicon mass block (500 μm), which can obtain a larger mass block in the same area compared with the traditional silicon surface processing technique (10-100 μm). The out diameter of the final tool is 50 mm with 10,000 mGal measurement range, 155˚C temperature and 100 MPa pressure rating. Apart from the 3-C micro-electro-mechanical gravity sensor, a 3-C fluxgate magnetic sensor is also integrated into the downhole tool. This allows us to measure both 3-C gravity field and 3-C magnetic field downhole simultaneously and conduct joint inversion of both the downhole 3-C gravity and 3-C magnetic data during the data processing stage. The prototype tool was tested in a borehole up to 850 m depth, and the 3-C gravity sensor inside the tool can measure the vibration of the environment during the stationary measurement downhole. The first test data set shows repeatability near 800 m depth, which verifies the adaptability of the micro-electro-mechanical-based gravimeter to the down instrument environment.

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“…The BHGM might be used in many applications that have been described in several studies (Rassmussen, 1973;Schultz, 1989;Ander;Herring, 1990;Brady and Wolcott, 1993;Alixant and Mann, 1995;Brady et al, 1998;Loermans and Kelder, 2006;Alshakhs et al, 2008). The BHGM might be used in many applications that have been described in several studies (Rassmussen, 1973;Schultz, 1989;Ander;Herring, 1990;Brady and Wolcott, 1993;Alixant and Mann, 1995;Brady et al, 1998;Loermans and Kelder, 2006;Alshakhs et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Inversion of Borehole Gravity Measurements for Reservoir Fluid Monitoring

Hadj-Sassi

Donadille

2010

All Days

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe fluids in the reservoir are redistributed in response to pressure gradients caused by hydrocarbon production, which is often coupled with injection of water or gas. It is known from density logging that the density of pore fluids is an important physical property useful in inferring oil, water, or gas saturation in a rock. Thanks to the density difference of the different phases, the borehole gravity measurement is a candidate for tracking the movement of fluids hundreds of feet away from wellbores. Such data are measured in time lapse to provide the three-dimensional distribution of density changes in time through an inversion procedure.Because gravity is a potential field, the inversion of borehole gravity data is inherently non-unique. The decrease of the sensitivity to the recorded data away from the measurement location is also a challenge for the inversion problem. The approach implemented in this work uses an iterative algorithm that minimizes a global objective function. The objective function includes the data misfit functional and a three-dimensional regularization that is needed to constrain the inversion to reasonable solutions. A weighting function based on the distance between each gravity source and the recording instrument is introduced to help mitigate the geometric decay of gravity kernels with distance from the sensor. Synthetic inversions are presented that indicate borehole gravity can be instrumental in detecting and monitoring a large water front. This study also points out the optimal conditions for using borehole gravity for fluid front monitoring, in terms of number of wells, relative well positions to the target, vertical sampling, and measurement accuracy.

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Borehole gravimetry: A review

Cited by 9 publications

References 1 publication

Density function evaluation from borehole gravity meter data – regularized spectral domain deconvolution approach

Density function evaluation from borehole gravity meter data – regularized spectral domain deconvolution approach

MEMS‐based 3‐C borehole gravimeter development

Three-Dimensional Inversion of Borehole Gravity Measurements for Reservoir Fluid Monitoring

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