By Angel Gonzalez and Susan Daker Of DOW JONES NEWSWIRES HOUSTON (Dow Jones)--BP PLC (BP, BP.LN) is studying the possibility of plugging a deep-water spill in the U.S. Gulf by injecting drilling mud from the surface into the mouth of the leaking well, a company executive said Monday. The method, to be studied in the next two days, could permanently stop one of the worst oil spills in U.S. history faster than doing so via a relief well that's scheduled to flood the leaking Macondo well with cement by mid-August, and the company will be making a decision about pursuing the option "over the next couple of days," said Kent Wells, a senior vice president for BP. The so-called "static kill" operation, which involves pumping heavy drilling mud into the Macondo well, is reminiscent of the "top kill" effort that failed last May. But now that BP has shut in the spill using a new containment system, it can pump mud at a low rate and keep it at low pressure, Wells said. The fact that the reservoir has lower pressure than at the time of the "top kill" may also make a new attempt possible, he said. Retired Coast Guard Adm. Thad Allen alluded to the static kill in a letter sent to BP Managing Director Robert Dudley, telling BP that the drilling of a relief well--long perceived to be the ultimate solution to the Deepwater Horizon spill--should be its priority. At a teleconference Monday, Wells said that the company still intends to drill the relief well even if it proceeds with the static kill option, to confirm that the leaking well is dead. The first of two relief wells is currently "looking directly" at the Macondo well, and will be able to intersect it at the end of July, he said. Wells's comments highlight the perception that the Deepwater Horizon gusher, which has spewed millions of barrels of oil into the Gulf of Mexico since April, may be close to an end. The oil flow has been shut in since BP installed a new containment cap on Thursday. That development, however, is accompanied by concern among U.S. officials about the integrity of the Macondo well and the possibility that if the well is damaged, oil and gas might seep from the neighboring sea floor. Wells said that sonar and seismic analysis hasn't picked up any anomalies in the well, and the fact that pressure keeps rising--albeit slowly--is a sign that the well could be in good shape. Pressure readings are currently at 6,811 pounds per square inch, and rising at 1 psi per hour, Wells said. Allen has said that the lower-than-expected pressure could be a sign of reservoir depletion, but could also indicate damage to the well. Oil-spill responders detected leaks around the cap and about 3 kilometers away from the well. The leak around the cap may not be "significant," although it is causing a formation of hydrates, crystal-like compounds that indicate the presence of hydrocarbons. The sea-floor leak, discovered during seismic testing and sonar analysis, is believed to be unrelated to the well cap, Allen said. Spill responders had originally planned on testing the cap and the well's integrity for a 48-hour period, which was to end Saturday. But the period has been extended in 24-hour increments at least until Tuesday afternoon. Tests to see if the cap can remain on the well are ongoing, Allen said. He said he and other responders are running down anomalies found during analysis but so far none of them appear to be serious enough to force BP to open the cap and move to a different containment option. BP has been working for 13 weeks to contain the gusher, which at one point was spewing up to 60,000 barrels of oil a day into the Gulf. -By Angel Gonzalez and Susan Daker, Dow Jones Newswires; (713) 547-9214; angel.gonzalez@dowjones.com (END) Dow Jones Newswires July 19, 2010 19:12 ET (23:12 GMT)