Geosteering and Drilling Challenges in a Faulted Reservoir Northern Oman

Day 4 Thu, November 15, 2018

et al. 2018

As one of the worst oil & gas business downturns struck, the need for a revolutionary approach of drilling was needed. Optimization was the key word during that period, it was about time to look back at drilling fundamentals, review and learn from previous failures and lessons while establishing new foundation for a transformed yet successful process that ensured an all-time historical success. While many trials of drilling optimization initiatives were executed over the years, inconsistent drilling performance delivery and repetitive failures continued to raise a red flag each time for variety of reasons. Drilling optimization in action was then introduced with its’ comprehensive drilling optimization package, where all historical norms, failures, lessons, and designs were analyzed thoroughly. New objectives and revised designs were proposed accompanied with a whole new process that ensured success. From challenges achieving required performance levels and dog legs in the top sections with increased risks of axial and lateral vibrations, to the difficulties faced in the landing section drilling through unconsolidated and reactive shales in the north, and through fragile weak formations in the south to the difficulties transferring weight to the bit at deeper depths in the horizontal laterals drilling highly porous zones of sticky limestones. Drilling optimization in action project was successfully introduced and executed with a renovated set of drilling parameters envelopes, revised trajectory designs, re-engineered BHA designs, right choice of fit for purpose bits models, adequate technology utilization and effective real-time performance reporting and monitoring. While cost optimization was the trend during the downturn, there was no better option to achieve desired financial results for both operator and service provider than the inclusion of the drilling optimization in action initiative into every well drilling program, it was proven to be an ultimate win-win technical and business solution.

Drilling Optimization in Action - Delivering 125 Field Records in 6 Quarters

Hawy

Busaidi

Day 4 Thu, November 15, 2018

et al. 2018

Successfully Drilling the Longest Shallow ERD Wells in the Sultanate of Oman

SPE/IATMI Asia Pacific Oil &Amp; Gas Conference and Exhibition

Busaidi

Awadalla

et al. 2020

An operator and a service company parternered in successfully drilling the longest extended-reach drilling (ERD) wells in the Sultanate of Oman. The project consisted of four wells to be drilled in the G field. These wells will be the first aquifer pumpoff wells drilled in the field with a goal of lowering the reservoir water cut (oil/water contact) for all nearby oil producers, and to minimize water production and maximize oil production. The buildup section required drilling through the risky gas cap and zones having possible total fluid losses. The risk of stuck pipe and the likelihood of gas kick, as well drilling through fractures on the horizontal section and experiencing potential total fluid losses, made successfully drilling the wells to TD even more difficult and challenging. The buildup section was divided into two string designs based on a previously used single-string design. The drilling objectives were to reduce and separate the risks in the different sections and to drill the gas cap formation in the 12.25-in. shale section, plus landing the well with possible fluid losses while entering the reservoir with the 8.5-in. bottomhole assembly (BHA). This drilling plan eliminated known risks, using BHAs for drilling the 12.25-in. section with a push-the-bit system, and drilling the 8.5-in. section with a high-buildup rate rotary steerable system (RSS) for dogleg severity assurance. Drilling both sections was performed with a near-bit gamma ray adapter for geostopping. The 6-in. lateral section was the main challenge in the drilling operations due to the anticipated highly fractured reservoir with possible total fluid losses and high-equivalent circulating density management. Poor borehole cleaning was expected due to the high-critical transport rate, as well severe shock and vibrations. The BHA was designed to be able to drill to TD using the following techniques: A finite element analysis (FEA) model was developed to determine the most excellent drillpipe to be used in terms of shock and vibration and buckling moments. The model recommended 4-in. drillpipe to reduce the high-surface pressure expected at TD.The FEA model helped in selecting the best driving system (motorized BHA) because the simulations indicated that the BHA would have lower shock and vibration and be able to handle the expected high-surface torque. Due to the expected faults and possible sidetrack, the final BHA selection was a motorized high-buildup rate RSS.The real-time parameter management and plan helped in selecting the best drilling parameters to minimize real-time shocks and vibrations. Drilling the buildup section with the two-casing string design solved the risk reduction and allowed for landing the four wells successfully. For the lateral section, the BHA design met the expectation of completing the drilling operation on one run to TD. Both companies teamed to successfully drill the two longest ERD wells in the Sultanate of Oman. All of the wells are in the very extended-reach group by ERD definition. Well G-55 is the longest ERD ratio well drilled to date by the operator with a 4.01 ratio.

Drilling Optimization in the Low-Resistive, Thin-Layer Reservoirs of Northern Oman

Awadalla

Oswaldo

Day 2 Tue, March 22, 2022

et al. 2022

Ultralow-resistivity reservoirs, common in Oman, are frequently encountered when drilling wells at the flank of an infill field with nearby oil/water contacts (OWC) in a reservoir sweet spot window of 1 to 2- m true stratigraphycal thickness (TST). An integrated solution developed to better position the wells in this type of reservoir has resulted in successful cases on net-to-gross (NTG), which exceeded expectations in terms of wells production and well deliveries. Integrating resistivity propagation curves response with directional resistivity curves (distance- to- boundary curves) response allows for optimizing well placement and assists in determining the best approach of well objective during drilling. Once drilling the lateral section began, a careful evaluation of the distance-to-boundary service tool inversion and directional measurements were performed in addition to conventional resistivity curves evaluation. This procedure ensured accurate placement of the well; thereby, avoiding water contact. Drilling optimization in long lateral sections has been carried out by optimizing bottom hole assembly (BHA) design, bit selection, and drilling parameters, taking geo-mechanics and geological uncertainty factors into consideration.