Hard Backreaming Due to Hole Shrinkage Through Carbonate Reservoir in Offshore Abu Dhabi

2021 ◽  
Author(s):  
Kimikazu Tsusaka ◽  
Tatsuya Fuji ◽  
Motohiro Toma ◽  
Kengo Fukuda ◽  
Michael Alexander Shaver ◽  
...  
Keyword(s):  
Drill Pipe ◽  
Poor Performance ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Borehole Wall ◽  
Abu Dhabi ◽  
Root Cause ◽  
Pull Out ◽  
Time Domain Data ◽  
Operational Time

Abstract The 3,000 ft long lateral holes drilled through water-injected area in the carbonate reservoir in the offshore Abu Dhabi have been forced to implement hard backreaming. The abnormal extra operational time has been taken due to poor performance in the operation to pull out a bottomhole assembly after drilling to the total depth. The study aims to analyze root-causes of the hard backreaming through the carbonate reservoir in the studied field. The speed of tripping-out was analyzed every stand of drill pipe by using time domain data of movement of traveling block. The correlations between the speed of tripping-out and rock characteristics such as porosity and constituent minerals in rocks were investigated. Hole shape was analyzed in the representative intervals of low trip-out speed using 16-sector caliper derived from azimuthal density logging. Stress concentration around the borehole wall was also analyzed using geomechanical model. The investigation revealed that hole shrinkage due to plastic deformation of the borehole wall was the most possible root-cause of the hard backreaming in the carbonate reservoir. Namely, BHA had to ream up deformed borehole wall in tripping-out. From the viewpoint of rock characteristics, the speed of tripping-out was found to be lower in the specific geologic layers with higher content of dolomite. This is because dolomite rocks cause larger resistance in reaming it in tripping-out since the strength of dolomite rocks is larger than that of limestone. Based on our findings, use of reamers on bit is found to be the better solution to improve the tripping-out performance in the problematic geologic layers instead of conventional operational attempts such as spotting of acid and use of high viscous fluids in hole cleaning. In addition, optimization of the design and position of reamers and stabilizers is essential to succeed in the future 10,000 ft long extended-reach wells in the studied oil field.

Geomechanical Modeling Based on the First Success of Micro-Frac Tests in the Nahr Umr Formation in Offshore Abu Dhabi

2021 ◽  
Author(s):  
Kimikazu Tsusaka ◽  
Tatsuya Fuji ◽  
Michael Alexander Shaver ◽  
Denya Pratama Yudhia ◽  
Motohiro Toma ◽  
...  
Keyword(s):  
In Situ Stress ◽  
Oil Field ◽  
Mechanical Anisotropy ◽  
Borehole Wall ◽  
Abu Dhabi ◽  
Stress Regime ◽  
Lost Circulation ◽  
Fracture Closure ◽  
Allowable Range

Abstract In the studied oil field in Offshore Abu Dhabi, the intermediate hole section has suffered from borehole instability and lost circulation in the higher inclination holes. Borehole instability occurs in the Nahr Umr formation. Lost circulation occurs in the Salabikh formation. This study aims to develop geomechanical model and to analyze mud weight (MW) for successful drilling through the two problematic formations in the studied oil field. In the Salabikh formation, spatial distribution of lost circulation pressure in hundreds of wells in the whole field was analyzed. The fracture closure pressure was also evaluated based on the extended leak-off test and fracture interpretation by image logging. In the Nahr Umr formation, Micro-Frac tests in a 6" hole were implemented to evaluate the minimum in-situ stress. This was the first direct measurement of the in-situ stress in the shale. The magnitude of SHMAX was back-analyzed based on the hole geometry using interpretation of six-arm caliper and analytical solution in the two key locations. This study clarified that severe lost circulation in the crest area was likely to occur due to reactivation of the pre-existing fractures in the Salabikh formation. The lost circulation pressure was found to be approximately 1.4 SG. The study also revealed that the in-situ stress regime in the Nahr Umr formation varied from the crest to flank areas. The crest and flank areas are reverse and nearly normal faulting stress regimes, respectively. Its transition area is strike-slip faulting stress regime. The regional difference in in-situ stress regime depends on the extent of mechanical anisotropy of the shale and the magnitude of tectonic strains. By integrating the results, with respect to the borehole stability analysis in the Nahr Umr formation, instead of a conventional lower hemisphere representation of the required MW based on failure width at borehole wall, the study analyzed the geometry of the failure area around the borehole wall under the allowable range of MW constrained by the lost circulation pressure in the Salabikh formation. As a result, the borehole failure cannot be avoided in any hole inclination in the Nahr Umr formation under the allowable range of MW to prevent severe lost circulation in the Salabikh formation. Therefore, appropriate practice to transport cavings is one of the key elements for safe drilling in higher hole inclination across the intermediate hole section in the studied oil field.

Immiscible WAG Injection Pilots Performance and Lessons Learnt in Carbonate Reservoir. Onshore Abu Dhabi Oil Field, United Arab Emirates

2012 ◽  
Author(s):  
Hamad Abdalla Al Shamsi ◽  
Abdulla B. Al-Katheeri ◽  
Ammar Faqqas Al Ameri ◽  
Abdul Samad Abdulrahman ◽  
Kashif Sajeel ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Abu Dhabi ◽  
Lessons Learnt ◽  
Wag Injection

Challenges of Optimizing Oil Recovery of "Tight Carbonate" Reservoir, Onshore Abu Dhabi Oil Field, United Arab Emirates

2008 ◽  
Author(s):  
Mohamed Benlacheheb ◽  
Adib Edris ◽  
Omar Sultan Al Jeelani ◽  
Salman Hassan Al Marzouqi ◽  
Maryam Al Sheehi ◽  
...  
Keyword(s):  
United Arab Emirates ◽  
Oil Recovery ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Abu Dhabi ◽  
Tight Carbonate

Successful Implementation of Underbalanced Drilling to Maximize Recovery from a Tight Carbonate Reservoir in an Onshore Oil Field, Abu Dhabi, UAE

2010 ◽  
Author(s):  
Tayba Abdulrahim Al-Hashemi ◽  
Adel Mohammed Al-Hammadi ◽  
Hassan Sohdy ◽  
Mostafa Haggag ◽  
Omar Sultan Al Jeelani ◽  
...  
Keyword(s):  
Carbonate Reservoir ◽  
Oil Field ◽  
Abu Dhabi ◽  
Successful Implementation ◽  
Underbalanced Drilling ◽  
Tight Carbonate

Integrated 1-D and 3-D Basin Modelling to Characterize the Deposition and Distribution of Asphaltenes Within Tar Zones from an Oil Field Offshore Abu Dhabi, UAE and Qatar

2021 ◽  
Author(s):  
Daniel Holloway ◽  
Ranald Kelly ◽  
Daniel Kay ◽  
Claire Gill ◽  
Masatoshi Ishibashi ◽  
...  
Keyword(s):  
Source Rock ◽  
Carbonate Reservoir ◽  
Oil Field ◽  
Source Rocks ◽  
Abu Dhabi ◽  
Hydrocarbon Generation ◽  
Peak Oil ◽  
Water Contact ◽  
Bulk Fluid ◽  
Basin Modelling

Abstract Increasing the recoverable reserves from oil fields by extracting from tar zones is becoming more desirable in the Middle East. One approach for improved definition of tar zones is to understand the factors which affected the deposition and distribution of asphaltenes within the target interval. In this paper we outline how integrated 1-D and 3-D basin modelling was used to identify the timing of hydrocarbon generation and expulsion from the Jurassic source rock to charge a prolific Jurassic carbonate reservoir formation of an oil field, offshore Abu Dhabi, UAE and Qatar. The source rock is modelled to be in the peak oil mature window today, with the onset of oil generation from the Cenomanian to the Turonian, depending on modelled and assumed source rock kinetics. The onset of oil expulsion was from the earliest Paleocene. Measured bulk fluid parameters in the reservoir formation have a significantly higher Gas-Oil Ratio (GOR) and elevated API gravity values when compared with predicted values. A possible mechanism to explain this discrepancy would be to invoke the contribution of higher GOR fluids from more mature source rocks within the fetch area of the field. Thermochemical sulphate reduction of anhydrite layers in the reservoir is predicted to have begun during the Eocene. Major uplift and erosion in the Oligocene and Mio-Pliocene significantly reduced reservoir pressure and temperature. This reduction in pressure and temperature is modelled to have caused precipitation of solids, gravity segregation and flocculation at the then oil-water contact, depositing the main tar zone and patchy tar in the reservoir beneath this zone as charge continued through time. We present a detailed review, interpretation and 3-D basin model; the first study of its kind conducted on this oil field. The 3-D basin model predicts the timing of the deposition and distribution of asphaltenes in the carbonate reservoirs of the studied field and demonstrate that local problems need to be understood in their regional context.

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