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Collaborating Authors
Smith Bits, a Schlumberger Company
New Ridge Diamond Elements Improve PDC Bit Efficiency
Gumich, D.. (Smith Bits, a Schlumberger Company) | Pak, M.. (Smith Bits, a Schlumberger Company) | Lomov, A.. (Smith Bits, a Schlumberger Company) | Gorobchenko, M.. (Smith Bits, a Schlumberger Company)
Abstract Rate of penetration is one of the key performance indicator for drilling process. PDC bits have the most efficient rock fracture mechanism: PDC cutters penetrate a rock and shear it layer by layer. Different PDC bit designs are created for special geological conditions during the optimization process. However, itโs not enough just developing bit designs, because the whole potential of diamond cutter elements are uncovered. Researching activity brought us new Ridge Diamond Element (RDE). It has tungsten carbide substrate like a conventional PDC cutter. Unique ridge shape of diamond table is a RDE distinguishing feature. This profile allows RDE to engage the rock more efficiently versus conventional PDC cutter. There is combination of two rock fracture mechanisms โ shearing and crushing. Laboratory tests have shown high performance of new diamond element: durability increasing, lower weight for cutter penetration the rock, bigger size of cuttings and higher rate of penetration. Efficiency of this new technology was proved by field tests in different Russian oil and gas regions.
- Europe > Russia (0.49)
- Asia > Russia > Siberian Federal District (0.30)
Novel Slim-Matrix PDC Construction Boosts Drilling Efficiency: A Field Study of Deep Applications
Sherif, M.. (Smith Bits, a Schlumberger Company) | El Oufy, M.. (Smith Bits, a Schlumberger Company) | Ragheb, A. M. (Smith Bits, a Schlumberger Company) | Aguib, K. A. (Smith Bits, a Schlumberger Company)
Abstract The ability to construct slim body matrix bits has been proven and demonstrated to be of value when compared to conventional matrix construction and steel body PDC bits. The new matrix material with enhanced toughness has shown it can take the drilling and dynamic loads of medium depth applications with low to medium compressive strength. However the technical limits possible using slim body construction needs to be established. Recent developments in applications drilling deep sections in medium to hard formations with extended intervals has shown a need to have heavy set PDC bits to be more hydraulically efficient. The construction of heavy set matrix bit has always suffered from tight junk slot area and open face volume because of the high blade count and dense cutting structure. The challenge with the rock column of deep sections is interbedding between soft formations and hard formations creating a need for a cutting structure to be durable but in the same time not suffer from poor cleaning when formation transitions to a softer member column. The new matrix material with enhanced toughness allows for the design of a slim-body PDC matrix construction. The technology was initially rolled out for 8ยฝ in and 12ยผ in shallow hole sections and results are recorded in SPE-KSA-113. The scope of this study is testing the structural integrity of this construction together with its effectiveness by extending the concept to heavy set bits and deploying them in deep interbedded rock column applications. The main value sought is that the drilling complexity and costs increase in deep applications and targeting improvement in ROP would have a direct consequence on cost per foot. In this context even an increase of 5% in ROP can have a significant effect if the hole depth is at 15,000 ft TVD. Thus this study focuses on measuring the success rate fo slim body matrix by measuring rate of ROP improvement while ensuring the structural integrity of this technology is not a risk at such depths. The severity of the applications in which these tests were conducted were evaluated when possible with rock compressive strength analysis and measuring that against ROP. The results portion of this part of the campaign (deep applications) has shown surprising results with more success rate percentage of improving ROP vs what was recorded in shallow applications (see SPE-KSA-113). The cost per foot effect was even more significant at such depth with the incremental improvement in ROP as the slim-body matrix construction responded to the variation of formation compressive strength. The slim body matrix feature proved its advantage in interbedded applications, where formations fluctuate from hard to soft and vice versa with no compromise to structural integrity even at the deepest applications drilled in Egypt's rock column.
- Geology > Rock Type (0.46)
- Geology > Petroleum Play Type > Unconventional Play (0.46)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drill Bits > Bit design (1.00)
Deep Water Nigerian Field Challenge: Increasing ROP with Centrally Located Conical Diamond Element Saves Operator 26Hours Rig-Time, Agbami Field
Jopling, Jacquelynn (Chevron Nigeria) | Dikko, Mustapha (Chevron Nigeria) | Obot, Etido Rufus (Smith Bits, a Schlumberger Company) | Okoro, Frank (Smith Bits, a Schlumberger Company) | Onyia, Jennifer Chioma (Smith Bits, a Schlumberger Company) | Gjertsen, Ole Jacob (Smith Bits, a Schlumberger Company) | Benny, Praveen Joseph (Smith Bits, a Schlumberger Company)
Abstract Drilling a 12ยผ-in hole section in the Agbami field offshore Nigeria presents a number of challenges.The section contains abrasive sandstone and shale that are interbedded with sandstone and siltstone, and all have unconfined compressive strengths (UCS) that vary across the field. The abrasive sandstone/shale section has UCS of 12,000 psi, and the interbedded sandstone/siltstone section has UCS of 15,000 psi or higher. The variation in lithology, formation strength, and abrasion/impact index make ensuring shoe to total depth (TD) runs with consistent ROP difficult because the conditions dull the polycrystalline diamond compact (PDC) bit's cutting structure, leading to a significant reduction in ROP before reaching section TD. An operator wanted to drill the 12ยผ-in section from shoe to TD in a single run with a 45% improvement in average ROP compared with the four-well offset median of 38.26 ft/h. To accomplish the objectives, the operator required a PDC bit with a differentiating drilling action designed to increase penetration rates and extend bit life in heterogeneous formations. A finite element analysis (FEA)-based modeling system was used to experiment with cutter types and their placement to improve drilling performance. Based on the modeling work, design engineers recommended a conical diamond element (CDE) with a thick synthetic diamond layer. The diamond layer on the CDE is approximately twice as thick as a conventional PDC cutter and exhibits 25% more wear resistance with almost double the impact strength. The element's unique geometry delivers high point loading for effective formation fracture. To fully exploit the CDE's advantages, the PDC bit body was redesigned by selectively abbreviating the blades at bit center and positioning a single CDE in the void space. The modeling system was also used to generate an operating parameter roadmap to maximize performance. The new 12ยผ-in central CDE bit drilled the 2,320-ft section from shoe to TD at 92.06 ft/h, a 102% increase in ROP compared with the best offset rate of 45.64 ft/h over a 2,419-ft interval. The performance improvement, which was achieved on the first deployment of the bit in this application, reduced drilling time by approximately 26 hours, saving the operator USD 1.2 million in offshore rig time. The bit design was deployed in another well where a comparatively heavier mud weight was used, but the run still recorded an outstanding increase in ROP over the best offset.
- North America > United States > Texas (1.00)
- Asia > Middle East (1.00)
- Africa > Nigeria > Gulf of Guinea > Niger Delta (0.62)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Sandstone (0.87)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.46)
- North America > United States > Texas > East Texas Salt Basin (0.99)
- North America > United States > Louisiana > East Texas Salt Basin (0.99)
- Asia > Middle East > Qatar > Arabian Gulf > Rub' al Khali Basin > North Field > Laffan Formation (0.99)
- (2 more...)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drill Bits > Bit design (1.00)
Solving Swelling Clay Issues in Egypt's Western Desert: Combination of Fluid Engineering and Steel-Body PDC Bit Displaces Roller Cone in Large Hole Section
Ahmad, M. F. (Shell Egypt) | Hussein, M.. (Shell Egypt) | Abd El-Azm, H. M. (Badr El Din Petroleum Company) | Hanafy, O.. (Smith Bits, a Schlumberger Company) | Eloufy, M.. (Smith Bits, a Schlumberger Company) | Ibrahim, S.. (Smith Bits, a Schlumberger Company) | Aguib, K.. (Smith Bits, a Schlumberger Company) | Farouk, A. A. (Bariod, a Halliburton Company) | Sabry, M. A. (Bariod, a Halliburton Company)
Abstract Drilling the top hole section in Egypt's Western Desert has proven to be a challenge because finding the optimal balance of drilling speed, pulling out of hole without issue, and running the casing without clay swelling is critical. Historically, a standard milled-tooth (MT) bit, slick BHA, and top hole mud system were used for economic considerations. Recently, a problem arose when drilling a 17ยฝ-in surface hole in the Western Desert Moghra sand and Dabaa area, where the formation is composed of swelling clays that caused delays and cost increases. The solution to combat clay swelling would require an effective mud strategy; a PDC design that could increase ROP and resist balling while remaining economic; and a slick BHA that ensured hole verticality without the aid of directional tools and minimizes the affect of drillstring dynamics for prolonged PDC bit life. The intent of such optimization is providing enough buffer time for the casing to be run without problems, and the overall solution needs to be more economic than the previous drilling practice. An integrated BHA, bit design, and mud strategy were deployed in a field test with outstanding results. The results showed a step-change in ROP performance and allowed a trouble-free hole. The PDC bit and slick BHA successfully mitigated vibrations and maintained verticality. The application of customized drilling fluid formulation that contained high-performance shale stabilizers with the redesigned mud-weight schedules and early fluid displacement resulted in significant enhancements in tripping while drilling as well as in running and cementing the 13โ -in casing.
- Geology > Mineral > Silicate > Phyllosilicate (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.41)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drilling Fluids and Materials (1.00)
- Well Drilling > Drill Bits > Bit design (1.00)
The Challenge of the Obayied Field: Novel PDC Design Sets New Performance Benchmarks in Egypt's Difficult Deep Western Desert Lithology Column
Moneim, M. A. (Shell Egypt) | Ahmad, M. F. (Shell Egypt) | Hanafy, O.. (Smith Bits, a Schlumberger Company) | Fayez, S.. (Smith Bits, a Schlumberger Company) | Eloufy, M.. (Smith Bits, a Schlumberger Company) | Aguib, K.. (Smith Bits, a Schlumberger Company)
Abstract Drilling the deep lithology column using PDC bits in the Obayied field of Egypt's Western Desert has been extremely difficult. The field's lithology column represents an amplification of all of the typical lithology characteristics in the Western Desert. The highly interbedded sandstone, siltstone, and shaleโalong with the variance of such interbedding across the fieldโhas been a significant challenge for well planners and has adversely affected cost per foot. The application is characterized as predominantly abrasive and impact-intensive in the same section, hence challenging for PDC bit durability. To efficiently drill the 8ยฝ-in interval, a fundamental change in PDC bit design is required. Considering these formidable challenges, service providers had to evolve PDC bits to meet the constant demand of improving performance and reducing costs. Focus was concentrated on balancing new technology developments and the willingness to invest on field trials. To accomplish these objectives in the Obayied field, the operator and the service provider identified two main problemsโdeveloping an in-depth understanding of rock strength characteristics of each individual formation in the deep rock column and its variance across the field, and developing PDC bits that can survive such a challenging rock column with improved durability and ROP. Recently, a novel conical diamond element (CDE) with extreme impact- and abrasion-resistant characteristics has been developed. The CDE has been incorporated at bit center in a new and innovative PDC design, solving the traditional challenge of the inefficient characteristic of PDC bit central area. In addition, a field-wide rock strength study based on sonic and gamma rays logs provided the transparency required for better planning and risk management to resolve the operational inefficiencies traditionally seen in the Obayied field. The new PDC bits utilizing the CDE technology has been deployed in Obayied and has reduced consumption to just 3โ4 bits per section in 2014, whereas that number was 8โ10 bits per section averaged in 2006. The new bit has also reduced the average number of days to drill the section from as low as 6 days to reach TD instead of 20 days. Performance gains were achieved both in ROP and footage totals in the most challenging formations, including Alam Al Buwaib, Upper Safa, and Lower Safa. The authors will discuss the benefits of this industry collaboration that achieved exceptional performance improvement leading to dramatic cost savings in the Obayied field.
- Africa > Middle East > Egypt (0.86)
- North America > United States (0.68)
- Africa > Middle East > Egypt > Western Desert > Khalda Concession > Lower Safa Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Egypt Field (0.97)
- Africa > Middle East > Egypt > Western Desert > Greater Western Dester Basin > Faghur Basin > Safa Formation (0.93)
Conical Diamond Element Bit Sets New Performance Benchmarks Drilling Hard and Abrasive Formations, Offshore Netherlands
Van Heekeren, H.. (TAQA Energie B.V.) | Storm, R.. (TAQA Energie B.V.) | Kraan, A. v. (Smith Bits, a Schlumberger Company) | Caycedo, A.. (Smith Bits, a Schlumberger Company) | Maliekkal, H.. (Smith Bits, a Schlumberger Company) | Azar, M. G. (Smith Bits, a Schlumberger Company) | White, A.. (Smith Bits, a Schlumberger Company)
Abstract In The Netherlands the operator drilling in the Southern North Sea area had to drill through Germanic Trias super group sequences to the reservoir sections in Buntsandstein formations of lower Triassic series at a depth of about 9,800-ft TVD that are highly abrasive and hard sandstone formations. These formations are overlaid by middle and upper Triassic clay stones interbedded with hard dolomite stringers. The compressive strength of these formations ranges from 5,000โ15,000 psi in the upper clay stones and from 15,000โ30,000 psi in the Buntsandstein group. Drilling the build and turn wellbore profiles using a directional BHA with roller cone and/or PDC has been challenging. In offsets, these bit types produced slow ROP and short run lengths, requiring multiple bit trips to complete the hole section. In many cases, the bits were pulled in poor dull condition with severe cutting structure damage. In some cases, the operator was forced to use diamond-impregnated bits on turbine to TD the section. To drill the section in one run and at higher ROP, the provider recommended a new-style conical diamond element bit that uses multiple conical shaped diamond elements (CDEs) positioned from bit center to gauge. The CDE's conical shape penetrates high-compressive-strength rock with a concentrated point loading that fails formation with a plowing mechanism. Design engineers used a finite-element-analysis (FEA)-based modeling system to strategically place the CDEs based on specific drilling parameters and formation characteristics. Recent R&D tests confirm the hybrid PDC bit drills with 25% less torque compared with conventional PDC cutters, providing increased directional control and smoother toolface response. The result is higher build rates that achieve directional objectives in less time. The new 513 design also included a centrally located CDE to enhance bit stability and mitigate shock and vibration. The bit was run on an RSS BHA and drilled 1,279 ft of difficult claystone and anhydrite/dolomite with silt/sandstone stringers at an average ROP of 31.04 ft/hr, 200% faster compared to the closest offsets in the reservoir sand. The bit also set a new single-run footage benchmark for this section in Block P15. The RSS BHA efficiently delivered all directional wellbore requirements, building inclination from 26ยฐ to 39ยฐ with a DLS of 3.42ยฐ/100 ft and 6.09ยฐ/100 ft in Sidetrack 1. As a result, the operator saved one day of rig time and a bit trip for a total savings of approximately USD 635,000.
- North America > United States > Texas (0.29)
- Europe > United Kingdom > North Sea (0.25)
- Europe > Norway > Norwegian Sea (0.25)
- (3 more...)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drill Bits > Bit design (1.00)
Offshore Exploration Program Benefits From Rolling PDC Cutter Technology, Timor Sea Australia
Giumelli, Martin (Eni Australia) | O'Shea, Paul (Eni Australia) | Maliardi, Alberto (Eni SpA) | Sosnowski, Paul (Smith Bits, a Schlumberger Company) | Shepherd, Aaron (Smith Bits, a Schlumberger Company) | Sadawarte, Sagar Sudhakar (Smith Bits, a Schlumberger Company) | Scordella, Maurizio (Smith Bits, a Schlumberger Company)
Abstract Exploration offshore Australia requires the operator to drill an 8ยฝโ vertical borehole through the difficult Plover sandstone. The highly abrasive formation, with unconfined compressive strength between 15โ30kpsi, has been problematic causing extremely short PDC bit runs and low rates of penetration (ROP). Erratic torque response was causing a reduction in bottom hole assembly (BHA) performance and system reliability. The operator required a PDC bit solution to increase run lengths and ROP. To solve the problems, a new system was devised that enables a PDC shearing element to fully rotate while drilling to increase cutting efficiency/bit durability while reducing frictional heat. To strategically position the rolling cutters (RC) to obtain maximum benefit, a forensic analysis was performed on PDCs used in offsets. After investigation, engineers identified accelerated wear flats in the shoulder area and a new PDC design (RC813) was implemented by positioning two 13mm rolling cutters in the shoulder area on each of the eight-blades. The target objectives would be to drill the 8ยฝโ hole section through the Plover with one PDC bit and improve ROP. The first well required one conventional PDC and one RC813 to drill through the Plover to TD. The standard PDC (10blades/16mm) drilled 90m (3739โ3829m) at an average ROP of 5.4m/hr. The bit was pulled for low ROP and graded 8โ3-CR-C-X-IN-BT-PR. The rolling cutter equipped RC813 drilled 126m (3829โ3955m) at a ROP of 4.3m/hr. The RC813 was pulled in good condition and dull graded 1-2-CT-S-X-IN-PN-TD. Parameter/bit adjustments in the second well enabled an RC813 to drill the entire Plover interval (3283mโ3425m) in one run at an ROP of 9.26m/hr. The rolling cutter PDC bit run was 319% faster than a direct offset that required four standard bits to TD the section at an average ROP of 3.1m/hr. The RC813 torque response was smooth compared to erratic torque response of standard PDC in Plover. The increased meterage and ROP saved the operator over $1million USD.
- Oceania > Australia > Western Australia > North West Shelf > Browse Basin > Block WA-315-P > Plover Formation (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Browse Basin > Block WA-274-P > Plover Formation (0.99)
- Oceania > Australia > Western Australia > Bonaparte Basin > Northern Bonaparte Basin (0.99)
New Erosion Resistance PDC Bit Coating Eliminates Balling in Water-Based Drilling Fluids, Saudi Arabia
Alvarez, Octavio (Saudi Aramco) | Mutair, Faisal (Saudi Aramco) | Ghannam, Hatem (Saudi Aramco) | Hassany, Usman (Smith Bits, a Schlumberger Company) | Siddik, Syed M. (Schlumberger) | Samy, Ahmed (Schlumberger)
Abstract The tendency of PDC (Polycrystalline Diamond Compact) bits to ball in soft shale formations when drilling with WBM is well documented, especially in deep/high-pressure applications. The capacity of shale to absorb water causes the formation to stick to the bit body and cutting structure compromising drilling efficiency. Balling also clogs the nozzles and junk slots reducing hydraulic effectiveness/cooling leading to accelerated cutter wear and premature bit failure. In Saudi Arabia's fields, a typical well requires approximately 1,600โ2,200 ft of a 12-in. vertical borehole or 3,000 ft of a 12-in. directional borehole to be drilled through carbonates, shale and claystone lithologies. The middle part of the section is composed of mainly claystone, which is the most problematic zone. In recent wells, bit balling incidents through the claystone interval was reducing average rate of penetration (ROP) to less than 10 ft/hr, and in certain cases forced to pull out of hole (POOH). PDC bits with various hydraulics configurations and non-stick coatings were tested in an attempt to alleviate balling issues. The thin layer eroded before the bit entered the problematic zone, exposing the rough bit body. An R&D initiative determined mechanical and electrochemical sticking contributes to bit balling. The investigation revealed a coarse bit body increases surface area and adhesive force. When mud flow stops an electrostatic force can cause clay to stick to the bit surface. Based on these findings a new type nickel-phosphorus electroplating process was implemented that creates a thick/durable coating with an extremely strong chemical bond. This paper reviews the investigation process and findings of three case studies in the Saudi Arabian fields. The new anti balling coating was applied to a seven bladed PDC design and run on a powered point-the-bit rotary steerable system. The bottom-hole assembly (BHA) drilled the entire section achieving a field ROP record. Drill bits with the new anti-balling coating were also tested in vertical wells in different gas fields setting new bit performance benchmarks. Application Review In a large gas field in Saudi Arabia, containing several distinctive sub-fields, a 12 in. hole size section needs to be drilled through a mixed sequence of rocks that are comprised of limestones, dolomites, anhydrites, siltstones and shales. A particularly problematic section of the well occurs through a shale formation that is reactive to hydration. In this section, bit balling, as well as stabilizer balling, is a known occurrence with the water-based mud that is utilized. This causes a drastic reduction in ROP and sometimes bits are pulled prematurely but they are typically in good condition once seen at surface (Fig. 1). Field experience has shown that the cutting structure is partially balled up while drilling, causing the low rates of penetration. Use of drilling fluid additives to help reduce the potential risks of bit balling has been investigated and introduced into the application, showing some improvements. The overall drilling performance through this interval, especially the low ROP, is still a major concern for the operator in these wells.
- North America > United States (1.00)
- Asia > Middle East > Saudi Arabia (1.00)
Innovative Modeling System Develops New PDC Bit Technology: Saves Operator 55% Drilling Time in First Deep Jurassic Slimhole Development Well, Kuwait
Al-Enezi, Dakhel (Kuwait Oil Company) | Al-Khaldy, Ali (Kuwait Oil Company) | Al-Mutawa, Faisal (Kuwait Oil Company) | Al-Mkhyal, Abdullah (Kuwait Oil Company) | Maliekkal, Harish (Smith Bits, a Schlumberger Company) | Ghoneim, Osama (Smith Bits, a Schlumberger Company) | Saleh, Mustafa (Smith Bits, a Schlumberger Company)
Abstract The North Kuwait Development Project requires a large-hole casing design to isolate problematic formations and enable the operator to reach deep HPHT target zones with maximum hole size. The most difficult section is Zubair to Hith traditionally drilled with 16" bits. These formations consist of abrasive/pyritic sandstone, reactive shale and carbonates with UCS between 5-30kpsi. Historically, to complete the 3900ft section required more than three PDCs or a combination of 4-5 PDC/TCI. To reduce costs, the first slimhole development well plan and string design was developed for Northern Kuwait fields. The objective would be to downsize the hole section from Zubair to Hith to 9ยผ" and drill to section TD with three PDCs. The production casing would be run from surface to TD instead of the conventional liner tie-back. To accomplish the objective, the team decided to develop two different 9ยผ" PDCs: 1) one for Zubair to Ratawi shale; 2) a second for drilling the remaining carbonates from Ratawi to Hith. To avoid costly field trials, an FEA-based modeling system was used to fully understand how iterative bit design changes would affect performance and drilling efficiency. Based on modeling, two PDC bits were implemented: a M819 with back-up cutters to achieve maximum durability and ROP through Zubair and push deep into Ratawi; a M616 to drill the remaining section from Ratawi to Hith. The bits were equipped with the latest HTHP cutters to enhance durability/ROP. The section was completed on a motor BHA in two bit runs saving 55% drilling time and the expense of a third bit. The operation set a new Kuwaiti record for the single longest 7ยพ" production casing string (13,625ft) and cementing back to surface. The downsizing strategy and increased drilling efficiency saved the operator $1 million USD compared to project estimates and a standard liner-string design.
- North America > United States > Texas (1.00)
- Asia > Middle East > Kuwait (0.94)
- North America > United States > Texas > East Texas Salt Basin (0.99)
- North America > United States > Louisiana > East Texas Salt Basin (0.99)
- Asia > Middle East > Kuwait > Jahra Governorate > Arabian Basin > Widyan Basin > North Kuwait Jurassic (NKJ) Fields > Marrat Formation > Upper Marrat Formation (0.98)
- (14 more...)
- Well Drilling > Drilling Operations (1.00)
- Well Drilling > Drill Bits > Bit design (1.00)
- Well Drilling > Casing and Cementing > Casing design (1.00)
Solving Hard/Abrasive Sedimentary and Igneous Formation Challenge: New PDC Bit Design Reduces 6-in Section Drilling Time By 47%
Peytchev, Peter (Cairn India Ltd) | Malik, Sumit D. (Cairn India Ltd) | Varghese, Roy (Cairn India Ltd) | Doodraj, Sunil (Cairn India Ltd) | Srinivasan, Sudarsan (Smith Bits, a Schlumberger Company) | Benny, Praveen (Smith Bits, a Schlumberger Company) | Raghav, Sanjeev (Smith Bits, a Schlumberger Company) | Narayanan, Shine (Smith Bits, a Schlumberger Company)
Abstract The 6"hole section in Raageshwari Field NW India (onshore) is typically between 600-800m long and highly challenging in terms of formation strength and abrasiveness. Lithology in the upper part is composed of sandstone, claystone and weathered basalt with unconfined compressive strength (UCS) between 3-5kpsi. The lower section contains basalt, felsic and sub-felsic igneous formations with UCS range of 15-30kpsi. Historically, a two bit strategy was employed. First, a PDC bit on a positive displacement motor (PDM) bottom hole assembly was used to drill the soft 6" section until ROP dropped to an unacceptable level. The BHA was then pulled and followed by a diamond impregnated bit on a turbine BHA to drill the very hard volcanics. Typical average on-bottom ROP for the entire section was 4.5m/hr and took approximately 170 hours to reach total depth (TD). To reduce costs, new technology was proposed to improve bit durability in the hard/abrasive volcanics and drill the entire 6" section in one run at a higher ROP. Recent bit and drilling data from offset wells was analyzed to assist in developing a new, cost effective PDC design to replace the expensive diamond-impregnated bits and drill the 6" hole section in one run. The study resulted in a new six-bladed PDC bit with 13mm cutters that incorporates superior cutter technology to improve durability and resist physical and thermal degradation. The design includes a row of backup cutters in the shoulder area to increase radial diamond volume for maximum durability. The new PDC bits have been run on a motor and rotary steerable bottom hole assemblies and drilled the 6" section on three consecutive wells in Raageshwari field totaling 2328meters with an average ROP of 10.7m/hr. This represents approx. 47% decrease in drilling time compared to that previously achieved by Impreg/TCI bit runs. Typically, the new bits are pulled in re-runable condition. This improved performance has saved the operator approximately six-days of rig time and approximately USD 480,000/well.
- North America > United States > Texas (1.00)
- Asia > Middle East (1.00)
- Asia > India > Rajasthan (1.00)
- Geology > Rock Type > Igneous Rock (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (0.90)
- North America > United States > Texas > East Texas Salt Basin (0.99)
- North America > United States > Louisiana > East Texas Salt Basin (0.99)
- Asia > India > Rajasthan > Rajasthan Basin > Barmer Basin > Rajasthan Block > Raageshwari Deep Field (0.99)
- (12 more...)