Intermediate casings in the build sections are subject to severe wear in extended-reach drilling. This paper presents a new method for predicting the depth of a wear groove on the intermediate casing. According to energy principle and dynamic accumulation of casing wear by tool joints, a model is established to calculate the wear area on the inner wall of the casing. The relationship functions between the wear groove depth and area are obtained based on the geometry relationship between the drillstring and the wear section and the assumption that the casing wear groove is crescent-shaped. The change of casing wear groove depth versus drilling footage under different-sized drillstrings is also discussed. A mechanical model is proposed for predicting casing wear location, which is based on the well trajectory and drillstring movement. The casing wear groove depth of a planned well is predicted with inversion of the casing wear factor from the drilled well and necessarily revised to improve the prediction accuracy for differences between the drilled well and the planned well. The method for predicting casing wear in extended-reach drilling is verifi ed through actual case study. The effect of drillstring size on casing wear should be taken into account in casing wear prediction.

Image segmentation as one of the primary steps in image analysis for object identification has received much attention lately, the main aim being to recognize homogeneous regions of an image which belong to different objects. A noise-robust edge detector SCHEME based on anisotropic Gaussian Kernels (ANGKs) is proposed in this paper by combining the region-merging algorithm to obtain higher quality segmentation results, which consist of three basic blocks. The first two blocks give rise to an initial partition of an image, while the last block attains the final segmentation by iteratively merging similar fragmented regions. A series of experiments is used to evaluate the performance of the method. The experimental results show that the proposed method has good noise robustness and localization accuracy, and can solve the problem of over-segmentation effectively, the simulation result supports our proposed main ideas.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractChina National Offshore Oil Corporation (CNOOC), Chevron, and ENI, the field operator, are partners in the development of the HZ oil and gas fields, operating as the CACT Operators Group (CACT) in the South China Sea. The HZ fields are stacked, thin, high-permeability sandstone reservoirs interlayered with low-permeability layers. The shallower layers generally have better permeability and were developed first while the deeper, lower-permeability reservoirs have been developed more recently.The lower-permeability reservoirs are generally of lower porosity and higher compressive strength. Drilling-mudfiltrate invasion also tends to be deeper. Deep-penetration perforating charges are required to perforate past the damaged zone. Experience indicates that underbalance perforation provides better productivity compared to overbalance perforation.Although conventional underbalance perforation can be performed using pipe-conveyed or tubing-conveyed perforation (TCP), depth uncertainties and the time requirement for TCP service in thin reservoir zones makes wireline-conveyed perforation an attractive method. However, where multiple zones must be perforated, the conventional wireline approach can only perforate the first zone underbalance (with the completion fluid weighted accordingly) while subsequent zones could only be perforated balanced at best. A new perforating system, designed to generate a large dynamic underbalance with a static overbalance, was used to perforate new wells for the development project to maximize well productivity per well expenditure.A multilayer production evaluation of one of the wells perforated with the dynamic underbalance method produced a zero skin value in the 9-md layer and a -0.97 skin value in the 1600-md layer. Conventional underbalanced perforation, employing multiple wireline runs, could not achieve these low skin values over this wide range of permeabilities. and z w = 15.4 ft in TVD, θ= 32 deg) 1.672 +/− 0.5 Completion Skin Factor Sensitivity Analysis Completion Skin Factor = 2 J ss , PI (STB/D/psi) 12.449 2.600 (stdev) J pss , PI (STB/D/psi) 13.254 2.780 (stdev) Completion Skin Factor = 1 J ss , PI (STB/D/psi) 13.546 2.931 (stdev) J pss , PI (STB/D/psi) 14.504 3.153 (stdev) Completion Skin Factor = 0 J ss , PI (STB/D/psi) 14.854 3.261 (stdev) J pss , PI (STB/D/psi) 16.015 3.537 (stdev) Completion Skin Factor = −1 J ss , PI (STB/D/psi) 16.443 3.607 (stdev) J pss , PI (STB/D/psi) 17.876 3.953 (stdev) Completion Skin Factor = −2 J ss , PI (STB/D/psi) 18.412 3.934 (stdev) J pss , PI (STB/D/psi) 20.228 4.377 (stdev)

No abstract

CACT-OG is a joint operating company consisting of CNOOC, ENI, and Chevron as its Principal Companies. CACT- OG is the operator of Huizhou HZ 25-4 oilfield in South China Sea, which was discovered in December of 2005 as multiple oil bearing zones found in the vertical exploratory well drilled by a semisubmersible rig. HZ 25-4 field is located in block 16/19 in central area of Pearl River mouth basin, located 6 km southwest of the HZ 19-2 platform in a water depth of 102 meters. After discovery, extensive studies were conducted for the development of this field. It was decided to upgrade the existing drilling rig on the nearby HZ 19-2 field platform and drill extended reach (ERD) wells from the platform. Three of five ERD wells were drilled and completed with 6" horizontal laterals and stand alone screens for sand control. A number of challenges appeared while drilling these wells including: ERD drilling experience level, excess torque and drag, hole instability, hole cleaning and resulting pack off, high side force and casing wear, high ECD due to shallow TVD, losses due to high ECD and fault encounter, and shock and vibration. The result of these challenges was long times to complete the wells and excess budget overruns. After the completion of the third well, it was been decided to suspend the operations and perform detailed analysis on the challenges with extensive lessons learned in order to approach the remaining two ERD wells in the Plan of Development with a different strategy. Following the studies and drilling analysis, the revised final plan included a new engineering design, revised operations procedures and monitoring, new approach for team building and training, and implementation of newer technologies such as utilization of Aluminum Drill Pipe and Continuous Circulating Devices. The result of the new plan applied has been a dramatic improvement in performance and consistent savings in budget. It has been observed that this different drilling approach and technology has opened a new window on how to drill challenging ERD, and that is a key to improved drilling performance.