Drilling a Horizontal wellbore between high-pressure water injectors and depleted producers

Community,

I’d like to pick your brains on a scenario we are looking at drilling and completing for a client.

• Heavily water-flooded area but showing very low sweep efficiency
• Overpressured injectors showing potential 1850kg/m3 (15.5+ppg) EMW BHP
• Vertical Producing wells are on rod pumps with as low as 300kg/m3 (2.5ppg) EMW BHP
• Very little communication between all these vertical injectors and vertical producers
• 7-8 week shut in pressures nearly holding at original injection pressures.
• We need to drill a horizontal leg right in the middle of these and although the injection pressures are not expected to transmit to our well +/-300m (1000ft) away on closest approach we need to be prepared for seeing an increased BHP while drilling.
• 244.4mm (9-5/8”) Surf csg at 200mMD/TVD (656ft MD/TVD)
• This is as deep as I can push since a potential low pressure shallow gas zone just below this.
• 177.8mm (7”) Intermediate top-set above potential pressure formation 1150mMD/971mTVD (3773ftMD/3185ftTVD)
• To me, this is the highest risk part of the well, drilling my intermediate hole into potential pressure with only surf csg exposed.
• Plan is to top set the upper-most formation that could transmit the pressure.
• 159mm (6-1/4”) Production hole to finish the build and go HZ.
• Max anticipated BHP nearer the heel, max depletion nearer TD
• Using 4-1/2” DP with DS40 connections
• Run 4-1/2” prod liner with frac sleeves and Weatherford OH Packers, uncemented.

We just did a well in this area using MPD equipment, light mud with backpressure, didn’t see any noticeable losses throughout, saw 1475kg/m3 (12.3ppg) EMW at TD, was prepared for maximum 1760kg/m3 (14.7ppg) EMW. Mudded up to KWM and got diff stuck. No noticeable losses to speak of.

We then preformed a flow test to see what flow rate potential this tight sand had to feed our wellbore with injection water, initial rate of 19m3/hr (120bbl/hr) but only saw 4m3 (25bbl) total fluid until it petered off to a trickle.

Mud system had been dusted up with BaseBlok to mitigate diff sticking but must have scraped it off. We did manage to get unstuck after displacing to base oil and pipe-free but the whole time we stayed at 1475kg/m3 (12.3ppg) balance to formation pressure.

Cleanout run went well, stripped through MPD kit to inside interm csg, spotted a heavy mud cap inside interm csg, POOH. Ran our liner and got diff stuck again outside interm csg.

Question: What are you experiences in dealing with high pressured heels with depleted toes where the potential pressures can be observed (at least partial pressure) and knowing the risk of diff sticking exists while drilling and running liner?

Thanks.

Keith Simard P.Eng

2 Answer(s)

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