|Publisher||Society of Petroleum Engineers||Language||English|
|Content Type||Conference Paper|
|Title||Nuclear Magnetic Resonance Logging; While Drilling, Wireline and Fluid Sampling|
Douglas J. Seifert, Ridvan Akkurt, SPE, and Saleh Al-Dossary, SPE, Saudi Aramco, and Ramez Shokeir, SPE, and Haluk Ersoz, SPE, Halliburton
SPE Middle East Oil and Gas Show and Conference, 11-14 March 2007, Kingdom of Bahrain
2007. Society of Petroleum Engineers
|6.6.1 Well Logging
Over the past decade, results from Nuclear Magnetic Resonance (NMR), logs have added significant value to petrophysical analysis by providing total, free-fluid and bound-fluid porosities. The development of Nuclear Magnetic Resonance tools for the LWD environment allows this valuable information to become available during the drilling operation, before significant invasion, allowing timely decisions, as well as reduced borehole risk.
Data from a Nuclear Magnetic Resonance Logging While Drilling tool (MRIL-WD) was acquired in a recently drilled well in Saudi Arabia. This well was extensively cored and logged. In addition to LWD NMR, wireline NMR logs (MRIL-Prime), and NMR fluid analyzers (MRILab) were also run.
This paper, following a brief discussion on the operation of MRIL-WD tool, compares and contrasts the results between while-drilling and wireline NMR logs. NMR fluid properties obtained from the NMR Fluid Analyzer are also crosschecked with the log data.
Obtaining Nuclear Magnetic Resonance data earlier in the drilling process will allow NMR logging to become one of the backbones of formation evaluation.
Nuclear Magnetic Resonance, NMR, logging technology has progressed very quickly in the past decade. Results from NMR logs have added significant value to petrophysical analysis by providing total, free-fluid and bound-fluid porosities. Recent introduction of NMR tools for the Logging While Drilling (LWD) environment allows for this valuable information to become available during the drilling operation for making timely decisions, before significant invasion and at reduced borehole risk. Additionally, an NMR Fluid Analyzer has been developed for measuring the NMR properties of the reservoir fluids downhole at reservoir conditions.
Saudi Aramco ran conventional wireline NMR, LWD NMR and a NMR Fluid Analyzer in a recently drilled well to evaluate the different technologies. A new LWD NMR tool was run while drilling and reaming, to compare against a similar wireline logging tool technology. The NMR Fluid Analyzer was also run to evaluate this new technology and to obtain NMR fluid data on reservoir fluids. This was the first well to integrate using a NMR-WD, NMR wireline and NMR Fluid Analyzer in the Middle East.
The data described in this paper is from an observation monitoring well. The field is particularly challenging in that many of these wells will have target entries 2 to 5 km from the surface location. As an added complication, two of the three main reservoirs have extensive tar mats near the oil-water contact. The tar mats effectively isolate the oil column from the aquifer, necessitating the drilling of water injection wells. These injection wells must be placed within a narrow oil column window above the tar mat to insure adequate injectivity and minimize any oil trapped behind the injectors.
NMR logging plays an important role in the development of the field because NMR data has been found to be extremely valuable in identifying and describing the tar bearing formations. Although wireline NMR logging technology has proven very efficient and accurate for tar detection, the desired acquisition mode for tar detection is real-time while drilling, not afterwards. Wells placed in or near the tar cannot meet the injectivity requirements since the tar effectively destroys the permeability. Therefore, the data needs to be available in real-time for geosteering for the proper placement of the wells. Furthermore, most of the formation evaluation in this field is being done utilizing LWD technology due to the vast majority of high angle and horizontal wells in the project. These are the two main reasons for testing LWD NMR technology in the field.
|File Size||905 KB||10|