TATNEFT Applies Technology of Drilling Small Diameter Wells

Technologies of drilling small diameter wells with a horizontal open wellbore are successfully implemented at OAO TATNEFT. Drilling of the fourth well at NGDU "Jalilneft” is at the stage of completion. One of the small diameter wells with a horizontal wellbore was completed at Ashalchinskoye field of NGDU "Nurlatneft" and one well was completed at each of NGDUs: "Almetyevneft" and "Jalilneft", respectively.

Drilling of horizontal wells is promising area, since it allows increasing the volumes of crude oil production, improving hydrocarbons recovery ratio and reducing operating and capital expenditures through optimizing the drilling spacing, as well as avoiding an early formation water breakthrough.

The difference of horizontal small diameter wells drilling of from traditional horizontal wells is that drilling below surface casing to the design well bottom depth is made with one 155.6 mm bit diameter and the interval above the producing formation is cased with 114 mm pipe string.

When drilling the wells with horizontal wellbores main risks and complications are associated with the upper horizons deposits characterized by unstable rocks. The Company‘s specialists apply modern technologies in order to minimize the risks mentioned, such as application of drilling mud with improved properties, drilling of telemetry controlled buildup and wellbore stabilizing sections with application of the same bottom hole assembly. The bottom hole assembly integrated telemetry system also includes a drill pipe GR logging module that allows defining the boundaries of Verey and Bashkirian deposits occurrence without interrupting the drilling process and performing reference logging.

Real-time while drilling geosteering information flows through the cell communication channels to computers of specialists of geological and technological services of NGDU, TatNIPIneft and OOO "Tatneft-LeninogorskRemServis" service company. This allows prompt controlling of the wellbore trajectory and positioning the horizontal wellbore section within the oil-saturated interval of the Bashkirian Stage, which is confirmed by the analysis of drill cuttings for hydrocarbon content.

After reaching the target depth 114 mm production casing with a casing packer is run through Verey sediments to save the reservoir properties of the open hole horizontal section. Cementing the production casing is performed with the rise of cement to the wellhead.