Tight oil filed A located in Songliao Basin North China has been producing for over 15 years. During Phase I, most of primary production came from vertical/directional wells with fracturing operation, the average production is 0.3 ton per well at the end of 2012 and only 8.78% oil recovery is recorded. This marginal oilfield stepped in to Phase II with a horizontal drilling campaign to increase final recovery rate.

The length of planned horizontal section more than 1500m for single well within extra thin tight reservoir (around 1.5m TST). Meanwhile, the budget is very limited during down turn. The drilling efficiency is the most crucial element to ensure the success for this project. Servals challenges was identified during pre-drilling assessment:

  • Dogleg severity(DLS) in this extra thin laminated reservoir is very unstable base on previous drilling practices

  • Ensure smoothly trajectory control within such narrow geosteering window with high rate of penetrate(ROP)

To overcome above challenges, an integrated solution was developed implemented to this drilling campaign:

  • Fit for purpose rotary steering system (RSS) was tested including the point-the-bit RSS and push-the bit in this project and found the best solution to ensure efficiency DLS finally.

  • A boundary mapper LWD tool with ability to map multiple key boundaries, this method not only support proactive geosteering to keep trajectory within narrow geosteering window and avoid unnecessary adjustment, out of target or sidetrack, but also can help to keep the trajectory within fast ROP zone during real-time operation.

Two typical wells were completed successfully. Outstanding outcomes have been observed by implementing this integrated approach in the complex target reservoirs. The drilling efficiency was improved by 38.7%~132.6% with smoothly trajectory control. The complex structure was identified clearly and the average Net to Gross (NTG) more that 97.5%, and the production reached to 18ton/day which far exceeding expectation.

The successfully application of the integrated solution in extra thin reservoir tight oil field will lead to improve drilling efficiency and save budget, increasing the production and well economics. We believe this approach and technique could address another similar formation development.

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