Real-time azimuthal acoustic measurements were introduced recently in the logging-while-drilling (LWD) industry. For the first time, this technology was used as part of the bottomhole assembly (BHA) to acquire information related to principal stress orientations in the deltaic to marine Zubair clastic sequence of onshore Kuwait. A deviated 8.5-in. hole section of the well was planned through sand-shale sublayers with a borehole inclination ranging from 46 to 88°. This section is characterized by time sensitive borehole deterioration and significant variations in pore pressure. These factors result in severe hole instability and ultimately stuck pipe events and require relatively high mud weights to maintain wellbore stability. LWD azimuthal acoustic technology, free from chemical sources, was used for the first time both in drilling and wipe modes to facilitate time-lapse field stress and wellbore stability analysis. Principal stress orientations were identified from three different sources, including borehole breakouts from azimuthal acoustic caliper, density image, and acoustic anisotropy evaluation. The results were then compared with the existing offset well data and an existing geomechanical 3D model. Variations in observed stress orientation, seismic reflection pattern, and pressure history in offset wells were used to map a fault that is responsible for bypassed oil and for the occurrence of tar and gas. The interpretation was extended to other low throw strike-slip faults; additional fault compartments were identified that could affect the pressure maintenance scheme of the field. This paper discusses the planning, design, and use of LWD azimuthal acoustic technology in this case history well. It also describes the viability, integrity, and reliability of the interpreted results and their use in a detailed geological interpretation in terms of stress orientation, fault trapping, and areal fluid variation. The optimization of real-time drilling operations and petrophysical data acquisition requirements are also investigated to improve future field development and overall reservoir management strategies.

Horizontal drilling technology was used for the first time in the Middle Cretaceous Lower Burgan Layered Sand reservoir of Raudhatain Field, Kuwait for enhancement of oil production. The reservoir has been on production using conventional development techniques for the past 50 years.The channel sands of the Lower Burgan Layered unit were targeted. These sands are much thinner than the world class Lower Burgan Massive Sand and became an ideal target for development by horizontal drilling. However these layered sands are very prolific and are at irreducible water saturation. These sands were de an ideal target for development by horizontal drilling. However these layered sands are very prolific and are at irreducible water saturation. These sands weic and are at irreducible water saturation. These sands were deposited in a clastic coastal environment. The complex geometry and heterogeneity make these sands a real challenge to place lateral boreholes within the sand.The challenge of horizontal drilling through thin sand is to expose significantly more reservoir rocks in the wellbore which helps to increase the productivity.This paper illustrates integration of LWD, geological, geophysical and engineering data for successful placement of the lateral sections within the targeted sands to maximize oil production.In the 1 st phase of horizontal drilling, laterals in 4 wells were placed in the Lower Burgan Layered sands at different locations over the Raudhatain structure. Length of laterals varied from 650 -2000ft depending on the spatial distribution and geometry of sand bodies' vis-à-vis oil column. Effective geosteering through 7-12ft thick oil sands in these wells encountered 0.5 -1.5 Darcy reservoirs. These oil sand layers produced from 850 BOPD to 4500 BOPD on initial production testing.The success obtained in producing from these sand layers proved to be very effective and greatly enhanced the production from Raudhatain Field, Kuwait.

Development in drilling technology allows horizontal and multilateral wells to increase hydrocarbon recovery and accelerate production from high water mobile reservoir by increasing the reservoir contact surface. In coning situations, such as production of oil reservoir with a bottom aquifer, multilateral wells reduce the coning affect and hence prove to be more cost effective. To address these challenges, first multilateral well with Level-4 junction combined with Inflow Control Device (ICD) was planned, designed and drilled in Upper Burgan Reservoir of Raudhatain Field, North Kuwait. The Upper Burgan Formation is layered sandstone–shale sequence deposited in deltaic settings having very fine to fine grained marine influenced channel sand as reservoir rock. Geosteering and evaluating these wells is very challenging without using a proper LWD technology. Indeed, the resistivity anisotropy is a major issue, especially if it occurs with influence of other bed boundary effects like resistivity of adjacent beds or polarization horn effects. Water coning issues in the field makes it even worse to interpret the resistivity data as they become spiky. To overcome these challenges the drilling bottom hole assembly was designed in the way to include the distance to boundary and the new Multi-function LWD sourceless technology. The capture gamma ray spectroscopy and formation sigma in real time has improved the petrophysical evaluation of this complex resistivity environment with mixed lithology in wells that are difficult or even costly to consider TLC wireline logging. The Lower Lateral of 2145′ with 8½" hole diameter was drilled through very fine grained sandstone in UB3 Lower zone and completed with 5" open hole ICD. The Upper Lateral of 1757′ was placed in UB3 upper zone having very good reservoir quality. This lateral was completed by 4½" open hole ICD. The production is comingled as the pressure difference between the two laterals was not more than 100 psi. The well operated under Electrical Submersible Pump (ESP) produced more than the estimated rate of oil during initial production. The success of the well not only addressed the issues related to enhancement of oil production and premature water break through but also opens up a new chapter of drilling multilateral wells in coming days in Raudhatain Field, North Kuwait. The paper covers the main challenges while well placement during geosteering to stay in the best quality of reservoir rock in structural and depositional complex settings and with the smart completion design for increase oil production and rate of recovery.

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The Cretaceous (Albian) Upper Burgan Formation has been on production for circa 60 years in the Raudhatain and Sabiriyah fields in North Kuwait and significant resources remain. Key to an optimized development of this important reservoir is the introduction of Slant Well technology incorporating the use of sliding sleeve completions. The Upper Burgan Formation in the Raudhatain Field consists of four major sand dominated layers that comprise the main producing zones. These likely represent high stand deposits that formed during a progradation of the delta system across the region. Separating the sand layers are non-reservoir mudrocks that were deposited in marginal marine settings and act as baffles or barriers to fluid flow. In order to maximize production from the Upper Burgan, KOC has instigated the use of high angle slant well technology which allows greater reservoir contact at the well bore for each sand layer. As well, all four layers are in contact with the well bore thereby maximizing the oil drainage more efficiently. Vertical wells achieve the same result, but the difference being far greater reservoir contact with the four major layers has been successfully accomplished with the Slant well, and this has afforded higher production rates. The use of the Slant well however is selective and horizontal well application is still in use in both fields where good sand continuity in a specific layer has been interpreted. Currently the non-conventional wells make up approximately 25 percent of the producers in the Raudhatain Upper Burgan, the rest being vertical wells. Drilling the Slant well is a challenge primarily due to the long intervals of shale that are encountered between the sand layers. Shale sloughing is the major problem. The Upper Burgan is a mature reservoir with a weak edge water drive. Pressure depletion is a concern that is mitigated with the use of an active sea water and effluent water flood program that is now in place. The first Slant well to be drilled in the Upper Burgan was RA-000A. The well, located in the southern part of the Raudhatain Field was drilled to a depth of 9858 feet with an inclination of 80 degrees through the productive intervals. The well was drilled to the top of the Upper Burgan and a 7 inch casing was landed at this depth and cemented. The productive interval was drilled with a 6 1/8 inch hole size having a length of 850 feet. The well was then completed with a sliding sleeve ICD (Inflow Control Device). The ICD completion in the Slant well allows more uniform production from different regions of the well bore with less draw down. This will minimize the water coning effect. The sliding sleeve can be used to shut off water producing intervals during the life of this producer. The successes and challenges of this well are explored in this paper.