Appraisal and Sweet Spot of the Deep Carbonate Unconventional Reservoirs of North Kuwait
Chinmaya Pattnaik¹, Rao Narhari Srinivasa¹, Vijay Kumar Kidambi¹, Neema Al-Ajmi¹, Samar Al-Ashwak¹, Musaed Al-Dousiri¹, Jonna Dayakar Rao¹, and Qasem Dashti¹
¹Kuwait Oil Company
Deep carbonate reservoirs of North Kuwait, occurring in the depth range of 13500 to 16500ft with a gross thickness of 2200ft, are characterized by large variability in reservoir properties. These reservoirs fall under the full spectrum of petroleum play ranging from resource play to tight oil/gas to conventional (2 to 24 PU and nano-Darcy to 100s of mDarcy). During the last few years, the focus of the field development activity in this area has been on conventional reservoir units. During this phase of field development, extensive subsurface data namely, conventional cores, image logs, geomechanical data and full suite of e-logs have been acquired and analysed. Some of the development wells, targeted on the conventional reservoir units, were designed to intersect the promising corridors of the unconventional parts through integration of seismic attribute data. Opportunistic successful well tests have also been carried out on some of the key unconventional sections of the reservoir. During this process of short and long term tests, valuable reservoir engineering data was acquired. This period also saw successful horizontal well placement, targeted on bed-bound-fractured reservoir section with commercial hydrocarbon production. All these efforts culminated in design of a systematic campaign for appraising these hitherto less understood/undeveloped reservoir units. One of the key lessons learnt during this phase of development work was to plan horizontal wells from the early phase of appraisal, facilitating large reservoir contact and interception of fractures.
Developing these units pose a number of drilling, well placement and completion challenges due to relatively thin nature of the tight reservoir units (10 to 50ft) with complex pore system. Containment of fracs in these thin units is an added challenge. A number of tailored well and completion concepts are designed to overcome the above challenges in different parts of the play area for different reservoir units. Considering the high uncertainty associated with these reservoirs, well designs are optimized to have a fall-back option for subsequent completion in the established production zone. Detailed subsurface studies and integration of large suite of data lead to ranking and prioritizing the sweet spots targeted on these unconventional reservoirs. Through this paper we are presenting the details of these unconventional plays, lessons learnt during appraisal and the early results.
AAPG Search and Discovery Article #90202 © AAPG/STGS Geoscience Technology Workshop, Eagle Ford plus Adjacent Plays and Extensions Workshop, February 24-26, 2014, San Antonio, Texas